Green synthesis and characterization of Syzygium cumini leaf-extract‑derived Cu 2 O/CuO@SiO2 nanoparticles for catalytic hydrogen production via NaBH 4 methanolysis

The synthesis of a CuO/Cu2O@SiO2 nanocomposite through a green route using Syzygium cumini leaf (SCL) extract as a reducing and stabilising agent was performed. Structural and morphological characterisation confirmed the formation of a nanostructured material with an average particle size of ~60 nm. Nitrogen adsorption–desorption analysis revealed a mesoporous structure, and the BET surface area was determined to be 120.4 m2 g−1. Under optimised conditions, a maximum hydrogen generation rate of 1900 mL min−1 g−1 was achieved. Thermodynamic parameters were found to be Ea = 16.35 kJ mol−1, ΔH = 16.215 kJ mol−1, ΔS = 265.61 J mol−1 K−1, and ΔG = −62 kJ mol−1, indicating a spontaneous process. Reusability studies demonstrated good catalytic stability with 84% activity retention after five cycles. The superior catalytic performance is attributed to the synergistic interaction between phases, high surface area, and enhanced active site density, highlighting its potential for sustainable hydrogen generation.