Cobalt-free CuO catalyst for hydrolytic dehydrogenation of sodium borohydride and ammonia borane

The environmental and economic impact of Co-based catalysts necessitates the use of a more environmentally friendly and less expensive catalyst, such as CuO. A cobalt-free CuO catalyst was developed via a simple low-temperature hydrothermal process. The efficiency of the catalyst was analysed for the dehydrogenation of NaBH4 as well as NH3BH3. Compared with the commercial particulate CuO, hydrothermally prepared CuO nanoplate (CuO HT) exhibits a good hydrogen evolution rate, the rate of hydrogen evolution for CuO_Commercial and CuO HT was experimentally measured to be 240 ml H2/min/g and 470.5 ml H2/min/g respectively for 0.2 g catalyst for the dehydrogenation of NaBH4. At a 10 times lower concentration of NaBH4 with 0.2 g of CuO HT catalyst, the rate of HER recorded was 1086 ml H2/min/g. The high catalytic activity of CuO HT could be related to the surface oxygen vacancies or defects generated due to the participation of high molar concentrations of NaOH during the reaction. The stability of both catalysts was investigated, and the rate of hydrogen evolution reaction after three cycles was determined to be 492 ml H2/min/ g for CuO_Commercial and 925.1 ml H2/min/g for CuO HT. Despite the fact that the rate of hydrogen evolution was observed to be increased for the third cycle, the volume of water displaced was decreased when compared to the first cycle, which could be due to the presence of a less active Cu2O phase retained after temperature treatment. Similarly, with the best catalyst concentration of CuO HT (0.2 g), the hydrogen evolution rate of NH3BH3 was also measured to be 1175 ml H2/min/gm. The result evokes a new insight into the evolution of sustainable and eco-friendly catalysts for a better hydrogen economy.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.