Synthesis and characterization of CdS@g-C3N4 catalyst for enhanced hydrogen generation using methanolysis of sodium borohydride

This study focuses on the fabrication and analysis of CdS/g-C3N4 composites to enhance hydrogen development using the methanolysis of sodium borohydride (NaBH4). Cadmium sulfide (CdS) nanoparticles were incorporated into graphitic carbon nitride (g-C3N4) at concentrations of 1 %, 2 %, and 3 % to investigate their structural, optical, and thermal properties. XRD and FTIR analyses confirmed the integration and preservation of key functional groups. UV-Vis spectroscopy demonstrated improved light absorption and a narrowed band gap, contributing to better catalytic performance. Thermogravimetric analysis (TGA) highlighted the nanocomposites' enhanced thermal stability, while SEM images displayed uniform CdS distribution across the g-C3N4 matrix. XPS results further validated strong electronic interactions between g-C3N4 and CdS, promoting potent charge transfer and reducing electron-hole recombination. The highest hydrogen evolution rate of 26,220 mL/g min for the CdS 1 %@g-C3N4 composite is due to the optimal synergy and effective electron transfer between CdS and g-C3N4. As CdS content increases to 2 % and 3 %, the rate drops to 23,451 and 20,266 mL/g min, respectively, likely because of nanoparticle aggregation, which hinders the catalytic efficiency. The activation energies for the CdS@g-C3N4 nanocomposites increase with higher CdS content, ranging from 30.32 kJ/mol for 1 % CdS to 40.32 kJ/mol for 3 % CdS, indicating a decrease in catalytic efficiency. The methanolysis mechanism, based on the Langmuir-Hinshelwood model, involves chemisorption of BH4- ions and subsequent hydrogen release. The synergistic influence of CdS and g-C3N4 enhances BH4- adsorption and electron transfer, significantly improving catalytic efficiency.