Home Amine-based synthesis of Fe3C nanomaterials: mechanism and impact of synthetic conditions
Article Publicly Available

Amine-based synthesis of Fe3C nanomaterials: mechanism and impact of synthetic conditions

  • Daniel P. Harris , Cheng Wan , Yuqi She , Brittney R. Beck , Daniel S. Forbes and Brian M. Leonard EMAIL logo
Published/Copyright: November 2, 2021
Download Article (PDF)
Become an author with De Gruyter Brill
Author Information Explore this Subject
Zeitschrift für Naturforschung B
From the journal Zeitschrift für Naturforschung B Volume 76 Issue 10-12

Abstract

Iron-based catalysts are a preferred variant of metal catalysts due to the high abundance of iron on earth. Iron carbide has been investigated in recent times as an electrochemical catalyst due to its potential as a great ORR catalyst. Using a unique amine-metal complex anion composite (AMAC) method, iron carbide/nitride nanoparticles (Fe3C and Fe3−x N) were synthesized through varying several reaction parameters. While the synthesis is generally quite robust and can easily afford phase pure Fe3C, it now has been shown that the particle size, morphology, excess carbon, and amount of nitrogen in the resulting nanomaterials can readily be tuned. In addition, it was discovered that Fe2N can be synthesized as an intermediate by stopping the reaction at a lower heating temperature. These nanomaterials were tested for their electrochemical activity in oxygen evolution reactions (OER).

Keywords: catalyst; iron carbide; nanomaterials; oxygen evolution reaction

1 Introduction

Iron carbide is one of most studied transition metal carbides (TMC) because of its magnetic properties and catalytic activity for the Fischer–Tropsch (F–T) reaction [1], [2], [3], [4], [5]. Iron is the second most abundant metal on earth, which makes it much cheaper than Pt and other noble metals. In the last 15 years, iron carbide has attracted a great deal of attention due to its exceptional catalytic activity for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) [6], [7], [8], [9], [10], [11], [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24]. Several iron-based materials have been studied for OER, but the primary focus has been on oxides, hydroxides, and oxyhydroxides [25, 26]. In standard applications, iron carbide catalysts must be protected by either carbon (i.e. graphene or carbon nanotubes) or nitrogen-doped (N-doped) carbon because they are very sensitive to surface oxidation [17–19, 21, 27]. Conveniently, a protective coating on iron carbide can also provide more oxygen adsorption sites for electrocatalysis and create stable, highly active catalytic materials.

Nitrogen-doped carbon has been of interest recently as support for catalysts due to a high surface area, chemical stability, and improved electrical conductivity over carbon supports [7]. As a support, the nitrogen in the carbon has a higher affinity for binding to a metal catalyst, and this allows for the formation of smaller metal nanoparticles on the support. N-doped carbon supports have the added benefit of being metal free catalysts for reactions such as OER, methanol oxidation, and ORR [28, 29]. The nitrogen heteroatoms in the N-doped carbon have three different sites based on their bonding or chemical environments: pyrrolic, pyridinic, and graphitic or quaternary. The pyrrolic nitrogen forms five membered rings while pyridinic nitrogen form 6-membered rings with the nitrogen exposed on an edge and the graphitic or quaternary nitrogen is embedded deep in the graphite structure [30], [31], [32]. In the N-doped carbon additives that have higher concentrations of e. g. pyridinic nitrogen have higher activity for ORR than other forms of nitrogen sites [33]. The pyridinic nitrogen sites have been shown to create highly active catalytic sites at the ortho carbon to the nitrogen. Synthetically controlling the pyridinic nitrogen sites and the overall nitrogen content in carbon would improve N-doped carbon as a catalyst and support.

There are a variety of synthetic techniques to synthesize N-doped carbon including thermal treatment, plasma treatments, CVD, and thermal decomposition [25, 31]. Thermal and plasma treatments typically use a carbon source such as graphene oxide and treat them with gases such as ammonia or hydrazine to dope nitrogen into the carbon structure [12, 32]. Alternatively, CVD methods react a mixture of nitrogen containing gas and carbon containing gas or a compound such as acetonitrile that contains both carbon and nitrogen. The products are then heated over catalytic metal foils to synthesize N-doped carbon structures. Lastly, thermal decomposition uses nitrogen containing organic or organometallic compounds which are then annealed to decompose the nitrogen containing compounds to a N-doped carbon material [11]. Syntheses of N-doped carbon supports for iron carbide typically are performed using the thermal decomposition route [33, 34] which allows for a one pot synthesis in which carbon precursors react and form both the nitrogen-doped carbon and iron carbide. One method for achieving thermal decomposition to form metal carbides and N-doped carbon is an amine-metal complex anion composite route (AMAC) [35–38].

The AMAC route utilizes anionic metal complexes and an onium salts of amines to produce a composite. The composite is subsequently annealed to synthesize a metal carbide. A variety of carbides was synthesized through either the AMAC or similar routes for example, molybdenum tungsten, niobium, and iron carbide. The AMAC route for molybdenum carbide synthesis allows a control of morphology, particle size, and unique phases [39]. Wan et al. reported that varying the amine gives rise to particle shapes of flowers, rods, flakes, and cubes [40]. They also produced new and rare phases of molybdenum carbide by adjusting the synthetic parameters such as temperature and, nature of the amine, and by adding stabilizers [39]. By utilizing an AMAC route that uses potassium ferrocyanide and various amines, it is possible to control the amount of nitrogen in N-doped carbon and the formation of new phases, morphologies, and particle sizes for the Fe3C catalyst.

Herein, a unique amine metal complex anion composite method (AMAC) was used to synthesize iron carbide/nitride with a carbon coating and different morphologies. We studied the reaction conditions including several different amines, the amine to metal ratio, and the reaction temperatures. Through these studies, we were able to modify several characteristics of the resulting Fe3C products including size, morphology, and the amount of carbon present. These materials were then tested for their catalytic activity for OER.

2 Experimental

2.1 Materials

4-chloro-ortho-phenylenediamine (4CloPDA), meta-phenylenediamine (mPDA), para-phenylenediamine (pPDA), 4-nitro-ortho-phenylenediamine (4NoPDA), aniline, 2-aminopyridine (2-pyr), 2-aminopyrimidine (2-pyrm), 2,4,6-triaminopyrimidine (2,4,6-pyrm), 2,6-diaminopyridine (2,6-pyr), multiwalled carbon nanotubes (MWCNTs) (OD × L = 6–9 × 5 μm), cobalt(II,III) oxide (<50 nm) were bought from Sigma Aldrich. Ethylene glycol, sulfuric acid, and 12 n hydrochloric acid were purchased from Fischer. 2,6-Diaminopyridine was bought from Janssen Chimica. Potassium ferrocyanide was purchased from Beantown chemicals and ortho-phenylenediamine (oPDA) from Sigma Aldrich and TCI America.

2.2 Synthesis of Fe3C

The amine metal complex anion composite was synthesized by first mixing potassium ferrocyanide and an organic amine in 150 mL of DI water. The solution was then stirred using a stir bar until the powders were fully dissolved. Next hydrochloric acid was pipetted in until the pH was around 1. The solution was then heated to 60 °C and allowed to continue reacting for two and a half hours. The reaction mixtures were then centrifuged to collect the composite which was dried at 60 °C in an oven. The composite was then placed into an alumina boat and into a tube furnace. The composite was then heated to either 675 or 750 °C with no dwell time under flowing argon to minimize oxidation.

2.3 Characterization

X-ray Diffraction (XRD) was collected using a Rigaku Smart Lab X-ray Diffractometer, with a CuKα source producing X-rays with a wavelength of 1.5406 Å. All X-ray reference data came from PDF2 database. Scanning Electron Microscopy (SEM) imaging was performed on a FEI QUANTA 450 instrument with a field emission electron source. For thermogravimetric and differential scanning calorimetry analysis a SDTQ600 from TA Instruments was used.

2.4 Electrochemical tests

Electrochemical tests were carried out using a three-electrode rotating disk electrode (RDE-2) and an EC potentiostat from BASi. The potentiostat used an Ag/AgCl (3 m NaCl) reference electrode, a graphite rod counter electrode, and a modified 3 mm diameter glassy carbon electrode (GCE) as the working electrode. Potentials were recalculated to reversible hydrogen electrode (RHE). The GCE was cleaned by polishing, followed by sonication in 0.1 m NaOH for 60 min. The iron carbide catalysts were then deposited by pipetting 3 μL of ink and air dried overnight. The ink suspension was prepared by tip sonicating 2 mg of catalyst in 250 μL of 18.2 MΩ ultrapure water and 50 μL of Nafion for 10 s. Electrochemical tests were performed in 0.5 m H2SO4 that was saturated with O2 for 1 h. Linear sweep voltammetry was scanned from 0 to 800 mV versus RHE at a scan rate of 10 mV s−1 with a rotation of 1600 RPM for 50 scans.

3 Results and discussion

All of the iron carbides/nitrides were synthesized by mixing potassium ferrocyanide (K4[Fe(CN)6]) and different amines (e.g. 4-chloro-ortho-phenylenediamine) in deionized water. The molar ratio of Fe:amine was typically 1:4, however several different ratios were utilized throughout this study (1:4, 1:2, 1:1, 1:0.5, 1:0.2, and 1:0.05) and all produce Fe3C as discussed below. The pH of the mixed solutions was adjusted to a value <3 by adding hydrochloric acid to protonate the amine and ensure formation of the amine-[Fe(CN)6] composite. The solution was then heated to 60 °C with stirring for 2.5 h and the precipitate was collected by centrifugation. The dried composites were annealed in a tube furnace under argon at different temperatures and times as explained in the following sections.

This AMAC method appears to be quite flexible regarding reaction conditions, which makes it a very convenient platform for conducting a systematic study of products and their resulting properties. The composites created by the solution reaction are crystalline products with an unknown structure. Previous studies on molybdenum oxide-amine composites have shown that the precursors form an organodiamine-templated structure with molybdenum oxide anion clusters. Other similar coordination polymers can also be formed by mixing an anionic metal complex with a cationic or protonated amine [41]. All of these structures appear ideal for the low-temperature formation of metal carbides. Upon annealing, the composite decomposes, and the resulting material contains nitrogen, carbon and iron. Thermogravimetric analysis (TGA) results for several different amines shows an initial weight loss that is likely due to vaporization of excess amines. Above 300 °C the iron and carbon components begin to react forming the nitride/carbide products.

Iron nitride (Fe3−x N) can readily be made by this method with different amines. 4-Chloro-ortho-phenylenediamine (4CloPDA) and meta-phenylenediamine (mPDA) (molar ratio of Fe to amine = 1:2 in the precursors) were used to make Fe3−x N as shown in Figure 1. The composites from both amines were heated to 675 °C and cooled down quickly (cooling rate: ∼50 K min−1) without dwelling. To obtain phase pure Fe3−x N (Figure 1, red) the as-made samples were then washed by excess deionized water for half an hour at room temperature.

Figure 1: XRD patterns of Fe3−x N made from an Fe:amine molar ratio of 1:2 with the precursors mPDA (blue) and 4CloPDA (black) at 675 °C. Below in green is the product obtained with 4CloPDA after water washing, showing the removal of KCl as a byproduct. The calculated Fe3−x N patterns shown at the bottom of the figure was reproduced from PDF: 00-001-1219.
Figure 1:

XRD patterns of Fe3−x N made from an Fe:amine molar ratio of 1:2 with the precursors mPDA (blue) and 4CloPDA (black) at 675 °C. Below in green is the product obtained with 4CloPDA after water washing, showing the removal of KCl as a byproduct. The calculated Fe3−x N patterns shown at the bottom of the figure was reproduced from PDF: 00-001-1219.

Further heating of the precursor produced Fe3C at 750 °C with residual KCl as a side product. The KCl can easily be washed away by heating the sample in ethylene glycol at 150 °C. Water was initially used but caused slight surface oxidation.

Several different amines including the previously mentioned 4CloPDA, mPDA as well as ortho-phenylenediamine (oPDA), para-phenylenediamine (pPDA), and 4-nitro-ortho-phenylenediamine (4NoPDA) were utilized to demonstrate the flexibility of this method and each produced Fe3C at the same temperature as seen in Figure 2.

Figure 2: (a) XRD patterns of Fe3C made from oPDA (black), mPDA (red), pPDA (blue), 4CloPDA (green), and 4NoPDA (purple) at 750 °C for 0 s dwell time. The reference data at the bottom of the figure for Fe3C was reproduced from PDF: 00-006-0688. (b)–(e) SEM images of the resulting Fe3C products. The molar ratio of Fe to amine was 1:2 in the precursors.
Figure 2:

(a) XRD patterns of Fe3C made from oPDA (black), mPDA (red), pPDA (blue), 4CloPDA (green), and 4NoPDA (purple) at 750 °C for 0 s dwell time. The reference data at the bottom of the figure for Fe3C was reproduced from PDF: 00-006-0688. (b)–(e) SEM images of the resulting Fe3C products. The molar ratio of Fe to amine was 1:2 in the precursors.

The scanning electron microscope images in Figure 2b–e show the typical morphologies of the iron carbides (Fe3C) synthesized by assorted amines. The particle shapes and sizes are quite random and varied, which is different from previously studied molybdenum and tungsten systems. The images clearly show that different amines (different molecular structures) lead to distinct particle shapes and sizes although the Fe3C particles were still surrounded by a carbon support. The morphologies of the carbon supports obtained by using pPDA (Figure 2b) are clearly different from that obtained with other amines (2c–e). Figure 2b shows that homogeneous microsize Fe3C particles are spread over the microrods (∼50 µm in length and 15 µm in width). Although the morphologies of the carbon supports are similar in Figure 2c–e, the size of the carbide clusters are different. Larger and less homogeneous Fe3C particles are observed using 4-nitro-ortho-phenylenediamine (4NoPDA, Figure 2d) and 4-Cl-ortho-phenylenediamine (4CloPDA, Figure 2e) compared with mPDA (Figure 2c) and pPDA (Figure 2b).

A lower Fe:amine molar ratio in the precursors was also studied to reduce the amount of free carbon in the final products. The ratios between iron and amine were controlled from 1:4 to 1:0.05 in the precursors, which resulted in slightly larger Fe3C particles and lower amounts of carbon in the final products.

According to the XRD data in Figure 3 and Supplementary Material Figure S1, Fe3C can be made at much lower Fe:amine ratios including 1:0.05 for oPDA (Figure 3) and mPDA (Supplementary Material Figure S1a) and 1:0.2 for pPDA. It should be noted that graphitic carbon (GC) (002) peaks appeared in some of the samples as shown in Supplementary Material Figure S1. While iron is known to be a catalyst for carbon nanomaterials including carbon nanotubes, this is still unusual because of the low annealing temperature (750 °C) and short dwell time (0 s) [42]. SEM was used to study the morphologies of Fe3C with lower Fe:amine ratios in the precursors. Both Figure 3b and 3c shows results for oPDA as the precursor, but the Fe:amine ratios are different (1:1 vs. 1:0.5). The lower amount of amine (1:0.5) gives predominantly Fe3C particles (brighter contrast) with less carbon support than for the 1:1 ratio. In addition, the particles are larger for the lower ratio likely due to the lack of carbon isolating the particles and allowing increased aggregation. The particle sizes were dramatically smaller using pPDA as the precursor regardless of the amine ratio as seen in the Supplementary Material Figure S2. Again, the amount of carbon can be controlled with the amine ratio, but the particle size is more consistent for pPDA. Therefore, the morphologies of Fe3C and carbon in the products can be controlled by choosing different amines and Fe:amine ratios.

Figure 3: XRD patterns of Fe3C made from oPDA at 750 °C for 0 s dwell time with different molar ratio of Fe to amine (1:2, 1:1, 1:0.5, 1:0.2, and 1:0.05). The reference data at the bottom of the figure for Fe3C was reproduced from PDF: 00-006-0688. (b) and (c) show the SEM images of the 1:1 and 1:0.5 Fe:amine ratio samples.
Figure 3:

XRD patterns of Fe3C made from oPDA at 750 °C for 0 s dwell time with different molar ratio of Fe to amine (1:2, 1:1, 1:0.5, 1:0.2, and 1:0.05). The reference data at the bottom of the figure for Fe3C was reproduced from PDF: 00-006-0688. (b) and (c) show the SEM images of the 1:1 and 1:0.5 Fe:amine ratio samples.

After observing graphitic carbon (GC) via XRD, a set of experiments was designed to form nitrogen-doped graphitic carbon. It has been reported that Fe3C supported on nitrogen-doped carbon (N-doped carbon) is an extremely good catalyst for oxygen reduction reactions (ORR) [8–12, 43]. N-doped GC has also been shown to play a critical role regarding the electrochemical catalytic activities (e.g. water splitting and oxygen reduction reactions). By utilizing different amines as both carbon and nitrogen sources, it could be possible to control both the amount and types of nitrogen present (pyridinic, pyrrolic, or graphitic) in the GC materials surrounding the Fe3C particles.

A series of nitrogen containing amine precursors was utilized to synthesize Fe3C. The amines were selected based on the number of amino groups on a benzene ring and the number of nitrogen atoms located in the benzene ring. All reactions except aniline were carried out using a 4:1 amine to metal ratio with at a temperature of 675 °C and no dwell time. For aniline we used an 8:1 amine to metal ratio with the same temperature and dwell time. Figure 4 demonstrates that all seven amines give Fe3C further emphasizing the generality of this synthesis method.

Figure 4: XRD patterns of the Fe3C products from different N-containing amine precursors. The molecular structures of the amines are shown below.
Figure 4:

XRD patterns of the Fe3C products from different N-containing amine precursors. The molecular structures of the amines are shown below.

SEM micrographs were taken to investigate the morphology and the particle sizes. Figure 5 shows that spherical Fe3C particles were synthesized, and some amines give rise to carbon shells on the particles. There was a general trend that samples with more carbon leftover had smaller Fe3C particles. For instance, melamine had very little carbon outside of the iron carbide and the particle size was around 1–5 μm. Conversely, aniline gave a larger carbon shell and particle sizes were <1 μm.

Figure 5: SEM images of Fe3C products from different N-containing amine precursors.
Figure 5:

SEM images of Fe3C products from different N-containing amine precursors.

Table 1. shows the % amounts of pyridinic, pyrrolic, graphitic nitrogen and the Fe2+ and Fe3+ oxidation states in the N-doped carbon. The % values were obtained by the XPS data shown in the Supplementary Material Figure S3. Also shown is the total % of carbon or N-doped carbon present in the product as determined by an oxidation reaction of the product via thermogravimetric analysis (TGA). The main trends that are seen show that more nitrogen in the ring of the amine causes more pyridinic and less graphitic nitrogen. These results suggest that the different amounts and types of nitrogen present in the starting materials has a direct impact on the type of nitrogen present in the N-doped carbon, we cannot exclude the possibility that the cyanide contributes to the C or N content of the final product. Ongoing experiments with different iron-based precursors are underway to further determine the source of the Nitrogen in the final product. Another interesting result can be interpreted when examining the 2-pyrimidine and melamine samples which have much higher percentage of Fe3+ compared to other amines. 2-Pyrimidine and melamine also leave the lowest amount of carbon by weight. The lack of carbon means that both samples do not have as much protection as the others and therefore are more likely to oxidize on the iron carbide. Additionally, there was not any nitride nitrogen (397.1 eV) observed by XPS implying that these materials are primarily iron carbide. However, we cannot rule out the possibility that some nitrogen substitution occurs on the carbon site which is especially important considering that at low temperatures an iron nitride phase was observed in Figure 1.

Table 1:

XPS analysis of Fe and N states and percentages % C/N from TGA.

Aniline 2-Pyr 2-Pyrm 2,4,6-Pyrm Mel mPDA 2,6-Pyr
Pyridinic 46.9 50.5 68.2 58.2 64.5 43.2 50.8
Pyrrolic 17.0 21.4 20.1 27.1 21.7 28.5 31.1
Graphitic 36.2 28.0 11.7 14.7 13.8 28.3 17.9
Fe2+ 45.3 72.1 33.5 68.8 40.4 48.2 69.3
Fe3+ 19.5 13.0 45.5 9.6 47.7 21.5 15.4
% C/N 28.6 58.9 61.7 26.3 74.2 18.2 31.8

4 Electrochemical tests

To further highlight the differences in the Fe3C formed using different amines, we tested the samples with the oxygen evolution reaction (OER) to determine what effect the amount of carbon and N dopants had on the overall activity. Figure 6 summarizes the OER tests for Fe3C made from different Fe:amine ratios in the precursors (1:4, black and 1:2, red) and commercial multiwall carbon nanotubes (MWCNTs, green). Commercial Co3O4 (gray) has been one of the most studied OER catalysts, and it which was used as a reference catalyst [37, 44–46]. Fe3C made from composites with a high amine content in the precursors was expected to have more free (graphitic) carbon in the final product, leading to higher OER activity. Fe3C made from the composite with a low amine content shows the second best OER activity, which might be due to less graphitic carbon in the sample. It should be noted that Fe3C made from different Fe:amine ratios in the precursor shows much lower overpotentials and higher current densities than commercial Co3O4. In addition, the polarization curves of the OER tests for as-made graphite from the sample of Fe3C/graphitic carbon and commercial MWCNT are seen to overlap, which means that they have similar OER activities. However, the Fe3C/graphitic carbon is a better catalyst than pure graphite itself. Therefore, both Fe3C and the graphitic carbon support play important roles in the OER. The carbon leads to more active sites in the samples, which are believed to make the Fe3C/graphitic carbon a better electrocatalyst. In order to study these active sites on the surfaces of the catalyst, other characterization techniques (e.g. scanning tunneling spectroscopy) and computational models need to be developed in the future.

Figure 6: (a) and (b) Polarization curves for Fe3C made from different Fe:amine ratios in the precursor (1:4, black and 1:2, red), as-made graphite (blue), commercial multiwall carbon nanotube (MWCNT, green), and commercial Co3O4 (gray) tested for the oxygen evolution (OER) activity in 0.1 m KOH with a scan rate of 2 mV s−1. Oxygen was flowing into the solution throughout the electrochemical tests.
Figure 6:

(a) and (b) Polarization curves for Fe3C made from different Fe:amine ratios in the precursor (1:4, black and 1:2, red), as-made graphite (blue), commercial multiwall carbon nanotube (MWCNT, green), and commercial Co3O4 (gray) tested for the oxygen evolution (OER) activity in 0.1 m KOH with a scan rate of 2 mV s−1. Oxygen was flowing into the solution throughout the electrochemical tests.

5 Conclusions

In the first part of the present study, both Fe3C and Fe3−x N nanoparticles were made using the amine-metal anion composite (AMAC) method with different Fe:amine ratios in the precursors. The morphologies of the final products could be controlled by varying the type and amount of amines. In the second part, a series of amines were used to synthesize phase pure Fe3C regarding the control over the formation of N-doped carbon, the particle size, the carbon amount, and the OER activity. It was found that more nitrogen in the ring of the heterocyclic amines leads to less pyridinic nitrogen and less carbon in the product. A larger number of amino groups at the heterocycles lead to a higher carbon content. SEM images have demonstrated that samples containing high carbon content have smaller Fe3C particles surrounded in protective carbon layers.

6 Supporting information

XRD, SEM, and XPS data for the additional iron carbide samples are given as supplementary material available online (https://doi.org/10.1515/znb-2021-0134).

Dedicated to: Professor Richard Dronskowski of the RWTH Aachen on the occasion of his 60th birthday.

Corresponding author: Brian M. Leonard, Department of Chemistry #3838, University of Wyoming, 1000 University Ave., Laramie, WY 82071, USA, E-mail:
Daniel P. Harris and Cheng Wan contributed equally to this work.

Funding source: National Science Foundation

Award Identifier / Grant number: NSF-DMR 1905914

  1. Author contributions: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.

  2. Research funding: This work was supported by NSF-DMR 1905914 (D.P.H. and B.M.L). D.S.F. and B.M.L. were also supported by NSF-CHE-1358498

  3. Conflict of interest statement: The authors declare no conflicts of interest regarding this article.

References

1. Park, H., Youn, D. H., Kim, J. Y., Kim, W. Y., Choi, Y. H., Lee, Y. H., Choi, S. H., Lee, J. S. ChemCatChem 2015, 7, 3488–3494; https://doi.org/10.1002/cctc.201500794.Search in Google Scholar

2. Zhao, S., Liu, X. W., Huo, C. F., Wen, X. D., Guo, W., Cao, D., Yang, Y., Li, Y. W., Wang, J., Jiao, H. Catal. Today 2016, 261, 93–100; https://doi.org/10.1016/j.cattod.2015.07.035.Search in Google Scholar

3. Le Caer, G., Dubois, J. M., Pijolat, M., Perrichon, V., Bussiere, P. J. Phys. Chem. 2002, 86, 4799–4808; https://doi.org/10.1021/j100221a030.Search in Google Scholar

4. Wu, A., Liu, D., Tong, L., Yu, L., Yang, H. CrystEngComm 2011, 13, 876–882; https://doi.org/10.1039/c0ce00328j.Search in Google Scholar

5. Komogortsev, S. V., Iskhakov, R. S., Balaev, A. D., Kudashov, A. G., Okotrub, A. V., Smirnov, S. I. Phys. Solid State 2007, 49, 734–738; https://doi.org/10.1134/s1063783407040233.Search in Google Scholar

6. Gu, L., Jiang, L., Jin, J., Liu, J., Sun, G. Carbon 2015, 82, 572–578; https://doi.org/10.1016/j.carbon.2014.11.010.Search in Google Scholar

7. Chen, M., Liu, J., Zhou, W., Lin, J., Shen, Z. Sci. Rep. 2015, 5, 10389; https://doi.org/10.1038/srep10389.Search in Google Scholar PubMed PubMed Central

8. Abbas, S. A., Ma, A., Seo, D., Jung, H., Lim, Y. J., Mehmood, A., Nam, K. M. Appl. Surf. Sci. 2021, 551, 149445; https://doi.org/10.1016/j.apsusc.2021.149445.Search in Google Scholar

9. Wen, Z., Ci, S., Zhang, F., Feng, X., Cui, S., Mao, S., Luo, S., He, Z., Chen, J. Adv. Mater. 2012, 24, 1399–1404; https://doi.org/10.1002/adma.201104392.Search in Google Scholar PubMed

10. Zhu, S., Lei, J., Zhang, L., Lu, L. Int. J. Hydrogen Energy 2019, 44, 16507–16515; https://doi.org/10.1016/j.ijhydene.2019.04.214.Search in Google Scholar

11. Hou, Y., Huang, T., Wen, Z., Mao, S., Cui, S., Chen, J. Adv. Energy Mater. 2014, 4, 1400337; https://doi.org/10.1002/aenm.201400337.Search in Google Scholar

12. Niu, Y., Teng, X., Wang, J., Liu, Y., Guo, L., Song, W., Chen, Z. ACS Sustain. Chem. Eng. 2019, 7, 13576–13583; https://doi.org/10.1021/acssuschemeng.9b03794.Search in Google Scholar

13. Zhao, Y., Zhang, J., Guo, X., Fan, H., Wu, W., Liu, H., Wang, G. J. Mater. Chem. A 2017, 5, 19672–19679; https://doi.org/10.1039/c7ta05936a.Search in Google Scholar

14. Yang, C. C., Zai, S. F., Zhou, Y. T., Du, L., Jiang, Q. Adv. Funct. Mater. 2019, 29, 1901949; https://doi.org/10.1002/adfm.201901949.Search in Google Scholar

15. Wei, L., Sun, H., Yang, T., Deng, S., Wu, M., Li, Z. Appl. Surf. Sci. 2018, 439, 439–446; https://doi.org/10.1016/j.apsusc.2018.01.056.Search in Google Scholar

16. Barman, B. K., Nanda, K. K. Green Chem. 2016, 18, 427–432; https://doi.org/10.1039/c5gc01405k.Search in Google Scholar

17. Liu, Y. L., Xu, E. Y., Sun, P. C., Chen, T. H. Int. J. Hydrogen Energy 2015, 40, 4531–4539; https://doi.org/10.1016/j.ijhydene.2015.02.018.Search in Google Scholar

18. Jiang, H., Yao, Y., Zhu, Y., Liu, Y., Su, Y., Yang, X., Li, C. ACS Appl. Mater. Interfaces 2015, 7, 21511–21520; https://doi.org/10.1021/acsami.5b06708.Search in Google Scholar PubMed

19. Hu, Y., Jensen, J. O., Zhang, W., Cleemann, L. N., Xing, W., Bjerrum, N. J., Li, Q. Angew. Chem. Int. Ed. 2014, 53, 3675–3679; https://doi.org/10.1002/anie.201400358.Search in Google Scholar PubMed

20. Kramm, U. J. Mater. Chem. A 2014, 2, 2663–2670; https://doi.org/10.1039/c3ta13821f.Search in Google Scholar

21. Zhang, Y., Jiang, W.-J., Guo, L., Zhang, X., Hu, J.-S., Wei, Z., Wan, L.-J. ACS Appl. Mater. Interfaces 2015, 7, 11508–11515; https://doi.org/10.1021/acsami.5b02467.Search in Google Scholar PubMed

22. Zhang, Y., Zai, J., He, K., Qian, X. Chem. Commun. 2018, 54, 3158–3161; https://doi.org/10.1039/c8cc01057a.Search in Google Scholar PubMed

23. Li, Z., Gao, Q., Liang, X., Zhang, H., Xiao, H., Xu, P., Liu, Z. Carbon 2019, 150, 93–100; https://doi.org/10.1016/j.carbon.2019.05.012.Search in Google Scholar

24. Fan, X., Peng, Z., Ye, R., Zhou, H., Guo, X. ACS Nano 2015, 9, 7407–7418; https://doi.org/10.1021/acsnano.5b02420.Search in Google Scholar PubMed

25. Bandal, H., Reddy, K. K., Chaugule, A., Kim, H. J. Power Sources 2018, 395, 106–127; https://doi.org/10.1016/j.jpowsour.2018.05.047.Search in Google Scholar

26. Hunter, B. M., Gray, H. B., Müller, A. M. Chem. Rev. 2016, 116, 14120–14136; https://doi.org/10.1021/acs.chemrev.6b00398.Search in Google Scholar PubMed

27. Reda, M., Hansen, H. A., Vegge, T. ACS Catal. 2018, 8, 10521–10529; https://doi.org/10.1021/acscatal.8b02167.Search in Google Scholar

28. Stacy, J., Regmi, Y. N., Leonard, B., Fan, M. Renew. Sustain. Energy Rev. 2017, 69, 401–414; https://doi.org/10.1016/j.rser.2016.09.135.Search in Google Scholar

29. Zhang, J., Zhao, Z., Xia, Z., Dai, L. Nat. Nanotechnol. 2015, 10, 444–452; https://doi.org/10.1038/nnano.2015.48.Search in Google Scholar PubMed

30. Rao, C. V., Cabrera, C. R., Ishikawa, Y. J. Phys. Chem. Lett. 2010, 1, 2622–2627; https://doi.org/10.1021/jz100971v.Search in Google Scholar

31. Wang, H., Maiyalagan, T., Wang, X. ACS Catal. 2012, 2, 781–794; https://doi.org/10.1021/cs200652y.Search in Google Scholar

32. Biddinger, E. J., von Deak, D., Ozkan, U. S. Top. Catal. 2009, 52, 1566–1574; https://doi.org/10.1007/s11244-009-9289-y.Search in Google Scholar

33. Zhu, Y., Zhang, B., Liu, X., Wang, D. W., Su, D. S. Angew. Chem. Int. Ed. 2014, 53, 10673–10677; https://doi.org/10.1002/anie.201405314.Search in Google Scholar PubMed

34. Bezerra, C. W. B., Zhang, L., Lee, K., Liu, H., Marques, A. L. B., Marques, E. P., Wang, H., Zhang, J. Electrochim. Acta 2008, 53, 4937–4951; https://doi.org/10.1016/j.electacta.2008.02.012.Search in Google Scholar

35. Xiao, Y., Hwang, J.-Y., Sun, Y.-K. J. Mater. Chem. A 2016, 4, 10379–10393; https://doi.org/10.1039/c6ta03832h.Search in Google Scholar

36. Kraupner, A., Antonietti, M., Palkovits, R., Schlicht, K., Giordano, C. J. Mater. Chem. 2010, 20, 6019–6022; https://doi.org/10.1039/c0jm00774a.Search in Google Scholar

37. Giordano, C., Kraupner, A., Fleischer, I., Henrich, C., Klingelhöfer, G., Antonietti, M. J. Mater. Chem. 2011, 21, 16963–16967; https://doi.org/10.1039/c1jm11744k.Search in Google Scholar

38. Giordano, C., Erpen, C., Yao, W., Antonietti, M. Nano Lett. 2008, 8, 4659–4663; https://doi.org/10.1021/nl8018593.Search in Google Scholar PubMed

39. Wan, C., Regmi, Y. N. Y. N., Leonard, B. M. Angew. Chem. Int. Ed. 2014, 53, 6407–6410; https://doi.org/10.1002/anie.201402998.Search in Google Scholar PubMed

40. Wan, C., Knight, N. A., Leonard, B. M. Chem. Commun. 2013, 49, 10409–10411; https://doi.org/10.1039/c3cc46551a.Search in Google Scholar PubMed

41. Hagrman, P. J., Hagrman, D., Zubieta, J. Angew. Chem. Int. Ed. 1999, 38, 2638–2684; https://doi.org/10.1002/(sici)1521-3773(19990917)38:18<2638::aid-anie2638>3.0.co;2-4.10.1002/(SICI)1521-3773(19990917)38:18<2638::AID-ANIE2638>3.0.CO;2-4Search in Google Scholar

42. He, Z., Maurice, J.-L., Gohier, A., Lee, C. S., Pribat, D., Cojocaru, C. S. Chem. Mater. 2011, 23, 5379–5387; https://doi.org/10.1021/cm202315j.Search in Google Scholar

43. Wu, Z.-Y., Xu, X.-X., Hu, B.-C., Liang, H.-W., Lin, Y., Chen, L.-F., Yu, S.-H. Angew. Chem. Int. Ed. 2015, 54, 8179–8183; https://doi.org/10.1002/anie.201502173.Search in Google Scholar

44. Trasatti, S. Electrochim. Acta 1984, 29, 1503–1512; https://doi.org/10.1016/0013-4686(84)85004-5.Search in Google Scholar

45. Koza, J. A., He, Z., Miller, A. S., Switzer, J. A. Chem. Mater. 2012, 24, 3567–3573; https://doi.org/10.1021/cm3012205.Search in Google Scholar

46. Li, Y., Li, F. M., Meng, X. Y., Li, S. N., Zeng, J. H., Chen, Y. ACS Catal. 2018, 8, 1913–1920; https://doi.org/10.1021/acscatal.7b03949.Search in Google Scholar

Supplementary Material

The online version of this article offers supplementary material (https://doi.org/10.1515/znb-2021-0134).

Received: 2021-09-03
Accepted: 2021-09-22
Published Online: 2021-11-02
Published in Print: 2021-11-25

© 2021 Walter de Gruyter GmbH, Berlin/Boston

Articles in the same Issue

  1. Frontmatter
  2. In this issue
  3. Laudatio/Preface
  4. Celebrating the 60th birthday of Richard Dronskowski
  5. Review
  6. Orbital-selective electronic excitation in phase-change memory materials: a brief review
  7. Research Articles
  8. Solving the puzzle of the dielectric nature of tantalum oxynitride perovskites
  9. d- and s-orbital populations in the d block: unbound atoms in physical vacuum versus chemical elements in condensed matter. A Dronskowski-population analysis
  10. Single-crystal structures of A 2SiF6 (A = Tl, Rb, Cs), a better structure model for Tl3[SiF6]F, and its novel tetragonal polymorph
  11. Na2La4(NH2)14·NH3, a lanthanum-rich intermediate in the ammonothermal synthesis of LaN and the effect of ammonia loss on the crystal structure
  12. Linarite from Cap Garonne
  13. Salts of octabismuth(2+) polycations crystallized from Lewis-acidic ionic liquids
  14. High-temperature diffraction experiments and phase diagram of ZrO2 and ZrSiO4
  15. Thermal conversion of the hydrous aluminosilicate LiAlSiO3(OH)2 into γ-eucryptite
  16. Crystal structure of mechanochemically prepared Ag2FeGeS4
  17. Effect of nanostructured Al2O3 on poly(ethylene oxide)-based solid polymer electrolytes
  18. Sr7N2Sn3: a layered antiperovskite-type nitride stannide containing zigzag chains of Sn4 polyanions
  19. Exploring the frontier between polar intermetallics and Zintl phases for the examples of the prolific ALnTnTe3-type alkali metal (A) lanthanide (Ln) late transition metal (Tn) tellurides
  20. Zwitterion coordination to configurationally flexible d 10 cations: synthesis and characterization of tetrakis(betaine) complexes of divalent Zn, Cd, and Hg
  21. An approach towards the synthesis of lithium and beryllium diphenylphosphinites
  22. Synthesis, crystal and electronic structure of CaNi2Al8
  23. Crystal and electronic structure of the new ternary phosphide Ho5Pd19P12
  24. Synthesis, structure, and magnetic properties of the quaternary oxysulfides Ln 5V3O7S6 (Ln = La, Ce)
  25. Synthesis, crystal and electronic structure of BaLi2Cd2Ge2
  26. Structural variations of trinitrato(terpyridine)lanthanoid complexes
  27. Preparation of CoGe2-type NiSn2 at 10 GPa
  28. Controlled exposure of CuO thin films through corrosion-protecting, ALD-deposited TiO2 overlayers
  29. Experimental and computational investigations of TiIrB: a new ternary boride with Ti1+x Rh2−x+y Ir3−y B3-type structure
  30. Synthesis and crystal structure of the lanthanum cyanurate complex La[H2N3C3O3]3 · 8.5 H2O
  31. Cd additive effect on self-flux growth of Cs-intercalated NbS2 superconducting single crystals
  32. 14N, 13C, and 119Sn solid-state NMR characterization of tin(II) carbodiimide Sn(NCN)
  33. Superexchange interactions in AgMF4 (M = Co, Ni, Cu) polymorphs
  34. Copper(I) iodide-based organic–inorganic hybrid compounds as phosphor materials
  35. On iodido bismuthates, bismuth complexes and polyiodides with bismuth in the system BiI3/18-crown-6/I2
  36. Synthesis, crystal structure and selected properties of K2[Ni(dien)2]{[Ni(dien)]2Ta6O19}·11 H2O
  37. First low-spin carbodiimide, Fe2(NCN)3, predicted from first-principles investigations
  38. A novel ternary bismuthide, NaMgBi: crystal and electronic structure and electrical properties
  39. Magnetic properties of 1D spin systems with compositional disorder of three-spin structural units
  40. Amine-based synthesis of Fe3C nanomaterials: mechanism and impact of synthetic conditions
  41. Enhanced phosphorescence of Pd(II) and Pt(II) complexes adsorbed onto Laponite for optical sensing of triplet molecular dioxygen in water
  42. Theoretical investigations of hydrogen absorption in the A15 intermetallics Ti3Sb and Ti3Ir
  43. Assembly of cobalt-p-sulfonatothiacalix[4]arene frameworks with phosphate, phosphite and phenylphosphonate ligands
  44. Chiral bis(pyrazolyl)methane copper(I) complexes and their application in nitrene transfer reactions
  45. UoC-6: a first MOF based on a perfluorinated trimesate ligand
  46. PbCN2 – an elucidation of its modifications and morphologies
  47. Flux synthesis, crystal structure and electronic properties of the layered rare earth metal boride silicide Er3Si5–x B. An example of a boron/silicon-ordered structure derived from the AlB2 structure type
https://doi.org/10.1515/znb-2021-0134
Keywords for this article
catalyst; iron carbide; nanomaterials; oxygen evolution reaction

Articles in the same Issue

  1. Frontmatter
  2. In this issue
  3. Laudatio/Preface
  4. Celebrating the 60th birthday of Richard Dronskowski
  5. Review
  6. Orbital-selective electronic excitation in phase-change memory materials: a brief review
  7. Research Articles
  8. Solving the puzzle of the dielectric nature of tantalum oxynitride perovskites
  9. d- and s-orbital populations in the d block: unbound atoms in physical vacuum versus chemical elements in condensed matter. A Dronskowski-population analysis
  10. Single-crystal structures of A 2SiF6 (A = Tl, Rb, Cs), a better structure model for Tl3[SiF6]F, and its novel tetragonal polymorph
  11. Na2La4(NH2)14·NH3, a lanthanum-rich intermediate in the ammonothermal synthesis of LaN and the effect of ammonia loss on the crystal structure
  12. Linarite from Cap Garonne
  13. Salts of octabismuth(2+) polycations crystallized from Lewis-acidic ionic liquids
  14. High-temperature diffraction experiments and phase diagram of ZrO2 and ZrSiO4
  15. Thermal conversion of the hydrous aluminosilicate LiAlSiO3(OH)2 into γ-eucryptite
  16. Crystal structure of mechanochemically prepared Ag2FeGeS4
  17. Effect of nanostructured Al2O3 on poly(ethylene oxide)-based solid polymer electrolytes
  18. Sr7N2Sn3: a layered antiperovskite-type nitride stannide containing zigzag chains of Sn4 polyanions
  19. Exploring the frontier between polar intermetallics and Zintl phases for the examples of the prolific ALnTnTe3-type alkali metal (A) lanthanide (Ln) late transition metal (Tn) tellurides
  20. Zwitterion coordination to configurationally flexible d 10 cations: synthesis and characterization of tetrakis(betaine) complexes of divalent Zn, Cd, and Hg
  21. An approach towards the synthesis of lithium and beryllium diphenylphosphinites
  22. Synthesis, crystal and electronic structure of CaNi2Al8
  23. Crystal and electronic structure of the new ternary phosphide Ho5Pd19P12
  24. Synthesis, structure, and magnetic properties of the quaternary oxysulfides Ln 5V3O7S6 (Ln = La, Ce)
  25. Synthesis, crystal and electronic structure of BaLi2Cd2Ge2
  26. Structural variations of trinitrato(terpyridine)lanthanoid complexes
  27. Preparation of CoGe2-type NiSn2 at 10 GPa
  28. Controlled exposure of CuO thin films through corrosion-protecting, ALD-deposited TiO2 overlayers
  29. Experimental and computational investigations of TiIrB: a new ternary boride with Ti1+x Rh2−x+y Ir3−y B3-type structure
  30. Synthesis and crystal structure of the lanthanum cyanurate complex La[H2N3C3O3]3 · 8.5 H2O
  31. Cd additive effect on self-flux growth of Cs-intercalated NbS2 superconducting single crystals
  32. 14N, 13C, and 119Sn solid-state NMR characterization of tin(II) carbodiimide Sn(NCN)
  33. Superexchange interactions in AgMF4 (M = Co, Ni, Cu) polymorphs
  34. Copper(I) iodide-based organic–inorganic hybrid compounds as phosphor materials
  35. On iodido bismuthates, bismuth complexes and polyiodides with bismuth in the system BiI3/18-crown-6/I2
  36. Synthesis, crystal structure and selected properties of K2[Ni(dien)2]{[Ni(dien)]2Ta6O19}·11 H2O
  37. First low-spin carbodiimide, Fe2(NCN)3, predicted from first-principles investigations
  38. A novel ternary bismuthide, NaMgBi: crystal and electronic structure and electrical properties
  39. Magnetic properties of 1D spin systems with compositional disorder of three-spin structural units
  40. Amine-based synthesis of Fe3C nanomaterials: mechanism and impact of synthetic conditions
  41. Enhanced phosphorescence of Pd(II) and Pt(II) complexes adsorbed onto Laponite for optical sensing of triplet molecular dioxygen in water
  42. Theoretical investigations of hydrogen absorption in the A15 intermetallics Ti3Sb and Ti3Ir
  43. Assembly of cobalt-p-sulfonatothiacalix[4]arene frameworks with phosphate, phosphite and phenylphosphonate ligands
  44. Chiral bis(pyrazolyl)methane copper(I) complexes and their application in nitrene transfer reactions
  45. UoC-6: a first MOF based on a perfluorinated trimesate ligand
  46. PbCN2 – an elucidation of its modifications and morphologies
  47. Flux synthesis, crystal structure and electronic properties of the layered rare earth metal boride silicide Er3Si5–x B. An example of a boron/silicon-ordered structure derived from the AlB2 structure type
Sign up now to receive a 20% welcome discount
Institutional Access
How does access work?
Have an idea on how to improve our website?
Please write us.
© 2025 De Gruyter Brill
Downloaded on 10.9.2025 from https://www.degruyterbrill.com/document/doi/10.1515/znb-2021-0134/html
Scroll to top button