Catalytic performance of nitrogen/sulfur-doped activated carbon-supported CuO composite in hydrogen production from NaBH4 methanolysis

Abstract

Increasing global energy demand and environmental concerns have increased interest in sustainable and clean energy technologies. In this context, hydrogen is considered one of the most important energy carriers of the future due to its high energy density and environmentally friendly properties. In this study, a nitrogen/sulfurdoped activated carbon-supported copper oxide composite (CuO@N,S@AC) was successfully synthesized for hydrogen production via the methanolysis of sodium borohydride (NaBH4), and its performance as a heterogeneous catalyst was investigated. The structural, morphological, surface, and chemical properties of the catalyst were comprehensively characterized using X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) surface area analysis, and Fourier transform infrared spectroscopy (FTIR) techniques. XPS results showed the successful presence of sulfur and copper species in the research spectrum confirmed the formation of the activated carbon-supported heteroatom-doped CuO composite structure. In NaBH4 methanolysis experiments, the catalyst exhibited high catalytic activity and reached a hydrogen production rate (HGR) of 13.782 mL min- 1 g- 1 at a volume of 0.25 g NaBH4. Kinetic studies calculated the activation energy (Ea) as 33.2 kJ mol-1, indicating that the catalyst has a low energy barrier for the reaction. The superior performance obtained was attributed to the synergistic interactions between CuO nanoparticles, sulfur doping, and porous activated carbon support. These interactions increased the active center density, facilitated electron transfer, and improved hydrogen production kinetics. Consequently, the CuO@N,S@AC catalyst stands out as a highly efficient and promising heterogeneous catalyst for NaBH4-based hydrogen production systems and is a significant candidate that can contribute to the development of sustainable hydrogen energy technologies.