Graphene Oxide–Graphite Composite Catalysts for Hydrogen Evolution in Sodium Borohydride Methanolysis

Abstract

Graphene oxide–graphite (GO–Gr) composite catalysts were successfully synthesized and evaluated for their performance in the methanolysis of sodium borohydride (NaBH₄) for hydrogen production. The catalysts were synthesized at four different GO to Gr ratios, with the optimal formulation identified as 75% GO and 25% Gr. The structural integrity and chemical composition of the composite were confirmed through a comprehensive set of characterization techniques, including X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS). Among the tested ratios, the 75% GO–25% Gr composite exhibited superior catalytic performance, achieving a hydrogen generation rate (HGR) of 44.19 L/min g_catalyst at 30 °C and an activation energy (E_a) of 14.55 kJ/mol, reflecting its high catalytic efficiency. Optimal performance was obtained using 150 mg of NaBH₄, 4 mL of methanol, and 5 mg of the composite catalyst. Reusability tests across five cycles demonstrated stable hydrogen production, confirming the catalyst’s durability. Furthermore, density functional theory (DFT) calculations and topological analyses revealed a hybrid electronic structure with a significantly reduced energy gap (ΔE = 0.136 eV), indicative of enhanced electronic reactivity. These theoretical insights corroborate the experimental findings, highlighting the GO–Gr composite as a highly effective and sustainable catalyst. By integrating the high surface functionality of GO with the conductive backbone of Gr, this composite offers a promising platform for advanced hydrogen production technologies.