Volume 239, Issue 1 - Special Issue: Solar Water Splitting And Artificial Photosynthesis (SWAP), Part 3; Guest Editors: Kevin Bethke, Jeyanthinath Mayandi and Smagul Karazhanov

In this study, a novel SnO 2 –Zr–F nanostructured composite was successfully synthesized through a mild chemical reaction. The crystalline nature of the composite was characterized using XRD, revealing an average crystalline size of 28.31 nm. FE-SEM images illustrated an agglomerated spherical morphology with appropriate elemental ratios. The optical properties of the nanocomposite are identified by UV–vis spectroscopy with Tauc plot, and the calculated bandgap is 2 eV. Photocatalytic activity was assessed against cationic (Rhodamine B) and anionic (Eosin yellow) dyes under sunlight for 150 min, resulting in a maximum degradation efficiency of 92 % and 98 %, respectively. Furthermore, the antibacterial performance of the composite was evaluated against S. aureus and E. coli bacteria. The findings suggest that the prepared nanocomposite exhibits promising potential for environmental applications, showcasing its efficacy in both photocatalytic and antibacterial domains.

Universally, energy loss in the form of heat is predominant and this heat is irrecoverable waste heat that leads to global warming. Clean, green, eco-friendly, cost-effective, and renewable energy sources are the possible solutions for this energy crisis and global warming issues. Thermoelectric power generation is a promising technology by converting this irrecoverable waste heat directly into electricity without any greenhouse gas emission. Nanostructured CaMnO 3 at various cerium concentrations have been successfully prepared by sol–gel hydrothermal method followed by annealing and sintering. Pure and doped samples were systematically characterized by DSC, powder XRD, RAMAN, SEM with EDAX and FTIR spectroscopy. Electrical and thermoelectrical measurements were carried out on the sintered pellets. The XRD analyses confirmed the formation of orthorhombic perovskite structure for all the samples and the average particle size lies in the range of 50–60 nm. FTIR analysis shows the presence of CaMnO 3 nanoparticles without any impurities. The temperature dependence of physical properties was performed and analyzed between room temperature and 600 °C. Electrical resistivity strongly depends on the nature of substituent ions and negative values indicate that the electrons are major charge carriers. Large Seebeck coefficient value and high-power factor make Ca 1− x Ce x MnO 3 an efficient thermoelectric material for energy storage applications.

This paper provides a thorough analysis of recent developments in radio frequency identification (RFID)-based biosensors and their uses in the medical industry. The most recent and cutting-edge technologies used in RFID sensors, as well as their operational procedures in the medical industry, are the main focus of this article. The most effective design methodology for RFID biosensors is determined by evaluating various design methodologies. The present state of the art technologies in this domain are also analyzed and discussed. This paper aims to support researchers in the development of inexpensive and widely available RFID-based biosensors that can improve medical and healthcare outcomes. The use of RFID biosensors in contemporary medical applications has demonstrated significant promise for enhancing patient care and facilitating the early diagnosis of a number of diseases. It is anticipated that RFID biosensor technology will maintain to play a significant role in the development of the medical field as it undergoes further development.

In this, we report the temperature-dependent magnetization [ M ( T )] in two distinct magnetic fields of 0.5 T and 5 T for Ni 47 Mn 40− x Si x In 3 ( x  = 1, 2, and 3) alloys. Using a phenomenological model and Maxwell’s thermodynamic relation, the values of the magnetic entropy change and specific heat capacity are calculated, and their values are also compared. The maximum magnetic entropy change and specific heat capacity peak values for different magnetic fields are both steadily reduced for the samples with x  = 1 to 3 samples, which is followed by an increase in relative cooling power value. In comparison to 0.5 T magnetic field, the samples investigate the highest values of magnetic entropy change (3.32, 2.81, 2.01 J kg −1  K −1 ) and specific heat capacity (32.37, 14, 4.32 J kg −1  K −1 ) with a magnetic field of 5 T. According to this finding, the sample is more responsible for the magnetic field than chemical pressure.

This study delves into the theoretical exploration of the structural and electronic characteristics of 2D monolayer MXenes (M n + 1 X n ) by the elimination of Al layers from their corresponding MAX-phases, M n + 1 AX n ( n = 1–3), through meticulous first-principles calculations. The study encompasses structural optimization and the determination of key ground state properties, including equilibrium lattice constants, energy ( E 0 ), and volume ( V 0 ) of both MXenes and their corresponding MAX phases. Consequently, we investigated the comparative study of the electronic properties of M n + 1 AlC n (M = Ti, V, or Cr) ( n = 1–3) and their MXenes for the first time by calculating the Bader charge analysis (MAX phase only) and the density of states (DOS). The analysis extends to the density of states and Bader charge assessments, facilitating a comprehensive comparison. Remarkably, the MXene monolayer showcases an elevated density of states at the Fermi level compared to its MAX phase counterpart. This disparity stems from the redistribution of 3d electrons near the Fermi level following the removal of Al layers, consequently enhancing electronic conductivity. Cohesive energy and formation energy calculations affirm the structural stability of these compounds. Furthermore, our computed values are meticulously cross-referenced with existing experimental and theoretical data, stimulating the reliability and significance of our findings.

Metal oxide-based electrode materials and redox additive electrolytes hold great promise as essential components of energy storage devices and have a great impact on their overall performance. Co 3 O 4 nanoflakes (NFs) have been prepared by a simple hydrothermal method. After thorough characterization of structure, functional group, and surface morphology, the potential of the as-prepared Co 3 O 4 NFs is assessed as an electrode material for a supercapacitor. The powder XRD analysis confirms the formation of the spinel cubic phase and space group Fd 3 ‾ $\bar{3}$ m . Morphological studies showed prepared Co 3 O 4 having nanoflakes-like structures and, with analysis by EDX, the presence of elemental composition has been confirmed. The electrochemical performance of the Co 3 O 4 electrodes has been studied in three electrode configurations using a redox-additive electrolyte. The electrode demonstrates enhanced supercapacitor performance with a redox additive electrolyte due to the reversible oxidation states of Co 2+ /Co 3+ and Fe 2+/ Fe 3+ , which significantly reinforced the Faradaic redox reaction. The CV curve has maintained its shape even at all scan rates, confirming the outstanding rate capability of the electrode. The Co 3 O 4 electrode showed a greater specific capacitance ( C sp ) of 611.16  F g −1 at a current density of 10 A g −1 in a redox additive electrolyte solution and capacitance retentions up to 69.23 % after 10,000 cycles. The calculated charge transfer resistance ( R ct ) of before and after GCD 10,000 cycles is obtained. The overall performance of the electrode material being consider as a promising candidate for supercapacitor applications.

The synthesis of metal oxide nanoparticles using natural extract encourages the futuristic design of an environmentally friendly system by getting rid of the dangerous, toxic substances. The food industry in India is paying a lot of attention to Myristica fragrans , often known as mace, due to its rich medicinal significance. In the current study, M. fragrans (Mace) aqueous extract was used to prepare copper oxide (CuO) nanoparticles. Phytochemical screening confirms the presence of bioactive substances such as alkaloids, sterols, glycosides, and flavonoids in the extract. XRD and SEM measurements show that the nanoparticles have a monoclinic structure with polyhedral shape. Using the Debye-Scherrer formula, the material’s average crystallite size was found to be 85 nm. Based on the Tauc plot, an optical band gap of the prepared CuO NPs was calculated as 2.6 eV. At room temperature, the material’s magnetic property was investigated using VSM analysis. Congo red was used to examine the photocatalytic properties of the materials with various timings. CuO nanoparticles’ antibacterial activity was evaluated at various doses against Staphylococcus aureus and Klebsiella pneumoniae . Almost, CuO NPs exhibit better response against both the bacteria. Moreover, research investigations using cyclic voltammetry was carried out to assess the produced nanoparticles’ pseudocapacitive qualities. At a scan rate of 10 mV s −1 , the material produced a good specific capacitance of 233.8 F/g with 1 M of KOH as an electrolyte.

ZnWO 4 /PANI was synthesized through the in-situ polymerization technique, revealing the wolframite monoclinic phase in its XRD pattern. The distinctive morphology of ZnWO 4 /PANI observed in the SEM image, exhibits enhanced redox sites, thereby improving its electrochemical performance. Cyclic voltammetry and galvanostatic charge-discharge studies confirm the pseudocapacitive behavior of ZnWO 4 /PANI, showcasing an impressive capacitance of 908 F g −1 at 1 A g −1 in 1 M KOH, along with a capacitive retention of 94 % over 5000 cycles. The robust conductivity of PANI and the narrow ion transport channels along with multiple oxidation states of ZnWO 4 contribute to the higher specific capacity, guiding the movement of electrons and ions. This study suggests a synergistic effect in ZnWO 4 /PANI, resulting in remarkable electrochemical performance enhancements.

In this article we report the structural, morphology, vibrational, optical and magnetic properties of Ba x La 1− x CoO 3 ( x  = 0, 0.05, and 0.1) (LBCO) samples. The X-ray diffraction shows that samples are in single rhombohedral phase. The Raman signals of LCO were quite small in comparison to LBCO, which exhibited a Raman peak above 675 cm −1 . The band seen with a wavenumber of 484 cm −1 corresponds to the vibrational modes of E g bending and Ba–O stretching. UV–DRS and photoluminescence spectra indicated broad absorption over the ultraviolet, visible, and near-infrared spectrums. Surface morphology and EDAX spectra corroborated the materials homogeneous size distribution and homogenous microstructure, with Ba indicating a more stable structure. XPS was used to study chemical states of LBCO and found Co (2p), La (3d), O (1s), and C (1s) elements in perovskite compounds. A peak beneath 300 eV indicated adventitious carbon on surface materials. XPS survey spectrum elements La, Ba, Co, and O had their own binding energies. The magnetization-field dependency of LBCO at 300 K showed that Ba insertion into the LCO switched it from paramagnetic to weak ferromagnetic. Ba considerably decreased magnetic saturation and coercivity, influencing magneto-crystallites’ anisotropy and coercive field.

We attempted to synthesize nickel oxide nanoparticles (NiO-NPs) utilizing waste Arachis hypogaea (peanut) shell extract and studied their structural, morphological, and biological performance for biomedical applications. The green engineered NiO-NPs possessed a face-centered cubic structure with an average particle size of 20 nm in highly crystalline form. NiO-NPs were shown to have an optical resonance peak at 327 nm with 3 eV as the optical band gap according to the UV–visible spectra, and the stretching band between Ni–O were evidenced from the FTIR and Raman spectrum. Utilizing green approach the stable nanoparticles were obtained with average particle size of 31 nm from SEM analysis; zeta potential value of −17.6 mV, and PDI as 0.68, revealed the formation of spherical nanoparticles with distinct morphologies without aggregation. XPS analysis confirmed the oxidation states of the elements Ni (2p) and O (1s). This approach may help to increase the surface area, increasing the possibility of nanoparticles interacting with bacterial cells. Furthermore, the presence of nickel and the oxygen oxidation state were confirmed by XPS. Proteus vulgaris , Streptococcus oralis , Bacillus subtilis , and Escherichia coli were found to be susceptible to the antibacterial action of the produced NiO-NPs, with a maximal zone of inhibition of 10.25 mm at 500 μg/ml for P. vulgaris . For P. vulgaris and E. coli , the minimum inhibitory concentrations of NiO were 5.36 and 12.55 %, respectively, at 31.25 μg mL −1 . We hereby claim that green engineered NiO NPs decorated with A. hypogaea shell extract have great potential for pharmaceutical and biomedical applications.