ABSTRACT This study investigates the complex dehydration kinetics of sodium sulfate decahydrate (Na2 SO4 .10H2 O). Analysis of TG/DTG data reveals that the dehydration process proceeds via five complex steps. Using isoconversional methods (FR, FWO, and DAEM), the kinetic parameters (Ea and ln A) of the individual steps were obtained. The Ea − α plots revealed that all deconvoluted processes are driven by a single reaction mechanism identified as a diffusion model (D3 ). A significant linear relationship between ln A and Ea with similar isokinetic temperatures characterized the kinetic compensation effect. Thermodynamic analysis indicates that the entire conversion is an endothermic and non-spontaneous process. 

In this study, we report on the synthesis and photoelectrochemical (PEC) performance of CdS/ZnO nanocomposite (NC) photoanodes annealed at varying temperatures (300, 350, 400, 450 °C). ZnO nanosheets (NSs) were initially deposited using a nanoparticle deposition system, followed by the spin coating deposition of CdS nanoparticles (NPs) and subsequent annealing. The fabricated NCs are environmentally friendly, binder-free, cost-effective, and scalable. Scanning Electron Microscopy of ZnO, CdS, and CdS/ZnO NCs annealed at 400 °C reveals that ZnO NSs are well-coated with CdS NPs, establishing strong interfacial bonding between the two materials. Structural analysis confirms the hexagonal wurtzite structure of ZnO, while the deposited CdS NPs remain amorphous. X-ray photoelectron spectroscopy shows the evolution of strong interfacial interactions between ZnO NSs and CdS NPs in the hybrid NCs. Optical studies reveal that the CdS-ZnO NCs exhibit stable band gaps (~ 3.21–3.23 eV), and the photoresponse current is significantly improved compared to pure ZnO and CdS photoanodes. The optimized CdS-ZnO NC photoanode (400 °C) shows the highest photocurrent of 2.44 mA ­cm–2 at − 0.14 V vs Hg/HgO and the highest current conversion efficiency of 1.58% at − 0.4 V vs Hg/HgO, demonstrating efficient solar water splitting performance. Comprehensive PEC analyses (EIS, OCP, Mott–Schottky) confirm that performance enhancement stems from improved charge separation and faster interfacial charge transfer with increasing annealing temperature.

Abstract—In the present work, the structural, electronic, and optical properties of the compound
have been studied. We carried out the plane-wave pseudo-potential approach within the framework of
the first principles of density functional theory (DFT) implemented with the Cambridge serial total energy
package (CASTEP) code. The electronic band structure reveals the metallic nature of the compound. The
computed geometrically optimized structure of the unit cell parameters was found to be in good agreement with the experimental monoclinic crystal structure data of the compound. For the first time, we have investigated the optical properties of since no other experimental or theoretical studies on the
optical properties and dielectric functions of have been reported yet. The reflectivity spectrum
shows that the reflectivity is high in the visible-ultraviolet region up to , indicating promise as a
good solar energy storage material.
Keywords: sodium sulfate decahydrate, electronic structure, first principle calculations, density functional theory