Volume 239, Issue 7 - Special Issue: Solar Water Splitting And Artificial Photosynthesis (SWAP), Part 8; Guest Editors: Kevin Bethke, Jeyanthinath Mayandi and Smagul Karazhanov

Comprehensive water quality control is a fundamental requirement for environmental preservation and the sustainable development of communities around the globe. To showcase the importance of local quality controls in identifying the sources of pollution, a case study was conducted to analyze the quality of drinking water from different locations along the Cauvery River from Mettur to Trichy (200 km) in Tamil Nadu, India. The quality of water samples from different locations was indexed and compared with the World Health Organization and Indian Standards of water quality. The results indicate some high local values of TDS, hardness, and chloride content. These high values may be due to effluents from industries, dying factories, and sewage from the urban areas on the banks of the Cauvery River. This is most prevalent near Mohanur, where industrial waste and effluents were directly linked into the river. The results emphasize the importance of local quality control for accurately pinpointing the factors affecting the environment.

This study examines the impact of copper ions (Cu 2+ ) on the structural, optical, and magnetic, characteristics of La 0.6 Sr 0.4 Mn 1-x Cu x O 3 (LSMCO) manganites. Various techniques, including X-ray diffraction, field emission scanning electron microscopy, Raman spectroscopy, DC magnetization, and photoluminescence measurements were employed for a comprehensive analysis. Structural examinations revealed that all compositions exhibit a single-phase orthorhombic structure. Raman spectroscopy reveals the structural distortion due to the inclusion of Cu at Mn site. The photoluminescence properties of the manganite were found to be influenced by the excitation wavelength, demonstrating energy transfer from Mn ions. Magnetic investigations indicated that the introduction of Cu leads to a reduction in the saturation magnetization of the manganite.

Two dimensional nanomaterials (2D) are considered to be one of the most important electrode materials in energy applications because of their unique structure with enhanced physical and chemical properties. To fabricate a high capacitance electrode material is a tedious process due to their low energy density and high self-discharge rate. In recent years, various transition metal sulphides and their composites have been widely used in electrochemical devices and electrocatalysis. Among them two dimensional tin sulphide nanoflakes (SnS 2 Nfs) have attracted increasing attention owing to their large surface area and interlayer crystal structure. Here, we investigated 2D SnS 2 Nfs is one of the promising materials for energy storage applications which was prepared through a simple hydrothermal process and the effect of structural, morphological and electrochemical properties were studied. As-synthesized SnS 2 Nfs were found to poses hexagonal phase structure with an average crystallite size of 28 nm were estimated from X-ray diffraction (XRD). FE-SEM image attributes the formation of hexagonal nanoflakes. The XPS spectrum revealed the Sn 3d and S 2p of the proposed material and the respective peaks are observed for SnS 2 Nfs. The as synthesized 2D SnS 2 Nfs exhibits high specific capacitance of 380 F/g at current density of 1 A/g and an excellent cyclic stability. The electrode retains 89 % of the initial capacitance after 3,000 cycle at high current density of 10 A/g.

Nickel Ferrite nanocrystalline material doped with transition metal ions (Zn 2+ , Co 2+ ) was obtained by chemical combustion method using respective nitrate hexahydrates and glycine as fuel. The phase purity of the prepared ceramic samples was ascertained using Powder X-ray diffraction (XRD) exhibiting an inverse cubic spinel structure with space group Fd 3 ‾ $\overline{\mathrm{3}}$ m . Lattice parameters follow the Vegard law, indicating a consistent lattice expansion. The formation of porous nanocrystalline ferrite was confirmed by Scanning Electron Microscopy (SEM) images and corroborated by Williamson-Hall analysis. Raman Spectroscopic analysis identified characteristic bands corresponding to vibrational modes of nickel ferrite (NiFe 2 O 4 ) and revealed shifts in the peak position with doping by zinc (Zn) and cobalt (Co). Vibrating Sample magnetometry (VSM) analysis indicated varied magnetic behaviour with different dopants and concentrations highlighting the influence of cation substitution on magnetic properties. The specific saturation magnetization ( M s ), remanent magnetization ( M r ) and coercivity ( H c ) are improved by the substitution of Zn 2+ and Co 2+ ions. This simple and cost-effective preparation technique holds promise for synthesizing high-quality nickel ferrite, which could find applications in magnetic and electronic devices.

The hydrothermal approach was used to prepare visible light active BiVO 4 –TiO 2 nanosheet composites in varying molar ratios. The photoluminescence (PL) spectrum, X-ray photoelectron spectroscopy (XPS), UV-Visible Diffuse Reflectance Spectroscopy (DRS), Transmission electroscopy (TEM), Brunauer-Emmett-Teller (BET) and field emission scanning electron microscopy (FESEM), were used to analyze the photocatalysts and composites. Photocatalytic activity of BiVO 4 –TiO 2 composites was investigated by decolorizing methylene blue. Out of four different molar ratio BiVO 4 –TiO 2 composites with a molar ratio of 3:1 BiVO 4 TiO 2 composite showed enhanced photocatalytic activity which is further proved by photoluminescence investigation of coumarin and Scavenger test. The DRS of BiVO 4 TiO 2 composite showed red shift in optical absorption. The enhanced photocatalytic activity is due to minimizing electron hole recombination by making composite with TiO 2 .

This study explores the synthesis and characterization of zinc molybdate (ZnMoO 4 ) nanosheets with emphasis on their potential application for energy storage devices particularly supercapacitors. The synthesis of ZnMoO 4 nanosheets was done through co-precipitation followed by examination of their structure, morphology, optical, thermal behaviour and electrochemical performance by various characterization techniques. X-ray diffraction (XRD) analysis confirmed that the formation of monoclinic ZnMoO 4 phase with the average crystallite size 17.93 nm. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) revealed that this material had nanosheets-like structure which helps to increase ion transport and surface area; these two factors are essential for enhancing the material’s supercapacitor efficacy. The semiconductor characteristics were determined using UV–Visible diffuse reflectance spectroscopy (UV-DRS) which indicated a band gap energy of 4.2 eV. Fourier transform infrared (FTIR) analysis confirmed that the presence of Zn–O and Mo–O bonds in their crystal lattice. Thermogravimetric analysis (TGA) showed that the ZnMoO 4 nanosheets had thermal stability since they experienced only a slight mass loss of 2.57 % up to 800 °C. Cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) tests were undertaken to find out the specific capacitance and the value is 618 F g⁻ 1 at a current density of 1 A g⁻ 1 .

In recent developments in solar energy research, Sb 2 Se 3 and Sb 2 S 3 emerge as environment friendly photovoltaic absorber materials, distinguished by their narrow bandgap and high absorption coefficient. Theoretical investigations to determine the electronic structure, effective density of states, dielectric function, and absorption coefficient of Sb 2 Se 3 and Sb 2 S 3 crystals have been performed using first-principle methods. The results reveal band gap values of about 0.822 and 1.757 eV (PBE method), 1.114 and 1.778 eV (HSE06 method) for Sb 2 Se 3 and Sb 2 S 3 , respectively. The valence band and conduction band edges are primarily formed by Se 4 p , S 3 p , and Sb 5 p hybridized orbitals. The effective density of states (DOS) exhibit magnitudes on the order of 10 19  cm −3 . Notably, anisotropic characteristics are observed in the real and imaginary parts of the dielectric function. Furthermore, the absorption coefficient surpasses 10 5  cm −1   at 1 and 1.2 eV for both Sb 2 Se 3 and Sb 2 S 3 . The result indicates that these highly efficient absorber materials are suitable in collecting solar energy.

This study involved the hydrothermal synthesis of vertically oriented TiO 2 nanorods on FTO substrate. We examined the impact of reaction duration on morphological, optical, structural and photoelectrochemical properties. The formation of TiO 2 nanorods was confirmed by the FESEM and AFM results. The formation of TiO 2 tetragonal crystal structure with the rutile phase was shown by XRD spectra. The average absorbance of the samples falls as the reaction duration increases, according to UV–vis spectroscopy analysis. According to PEC experiments, each sample demonstrated a strong photocurrent density and good light response in various lighting situations. The highest possible photocurrent density of 91.8 μA/cm 2 at 1.2 V vs Ag/AgCl was recorded from TiO 2 film with the reaction duration of 5 h (T@5 h). The quick separation and transfer of photogenerated charge carriers was demonstrated, and this result was confirmed by EIS data.