Highly Active and Robust Catalyst: Co₂B–Fe₂B Heterostructural Nanosheets with Abundant Defects for Hydrogen Production

Abstract

A high-performance and reusable nonnoble metal catalyst for catalyzing sodium borohydride (NaBH₄) hydrolysis to generate H₂ is heralded as a nuclear material for the fast-growing hydrogen economy. Boron vacancy serves as a flexible defect site that can effectively regulate the catalytic hydrolysis performance. Herein, we construct a uniformly dispersed and boron vacancy-rich nonnoble metal Co₂B-Fe₂B catalyst via the hard template method. The optimized Co₂B-Fe₂B exhibits superior performance toward NaBH₄ hydrolysis, with a high hydrogen generation rate (5315.8 mL min^-1 g_catalyst^-1), relatively low activation energy (35.4 kJ mol^-1), and remarkable cycling stability, outperforming the majority of reported catalysts. Studies have shown that electron transfer from Fe₂B to Co₂B, as well as abundant boron defects, can effectively modulate the charge carrier concentration of Co₂B-Fe₂B catalysts. Density functional theory calculations confirm that the outer electron cloud density of Co₂B is higher than that of Fe₂B, among which Co₂B with high electron cloud density can selectively adsorb BH₄^- ions, while the electron-deficient Fe₂B is favorable for capturing H₂O molecules, therefore synergistically promoting the catalytic NaBH₄ hydrolysis to produce H₂.