Highly efficient visible-light-driven catalytic hydrogen evolution from ammonia borane using non-precious metal nanoparticles supported by graphitic carbon nitride

Abstract

A series of non-precious monometallic (Co, Ni and Fe) and bimetallic (CuCo, FeCo, NiCo, CuNi and FeNi) nanoparticles (NPs) supported by semiconductor graphitic carbon nitride (g-C₃N₄) was synthesized, which was used to catalyze hydrogen evolution from ammonia borane (NH₃BH₃) under visible light irradiation at 298 K. The systematic investigation showed that in comparison with the activities of all the catalysts in the dark, their activities were remarkably enhanced under visible light irradiation. Particularly, the in situ-synthesized Co, FeCo and CuCo catalysts exhibited visible-light-driven activities featuring total turnover frequency (TOF) values of 55.6, 68.2 and 75.1 min⁻¹, respectively, which were the highest amongst the values of the reported noble-metal-free catalysts at 298 K. The enhancement of activities could be ascribed to the enrichment of the electron density of the active metal NPs under visible light irradiation, which was caused by the Mott–Schottky effect at the g-C₃N₄–metal interface. Furthermore, the catalytic activities of the catalysts strongly depended on the wavelength and intensity of the incident light, indicating that the visible light irradiation indeed played a key role in the enhancement of catalytic activities.