Interfacial charge transfer induced dual-active-sites of heterostructured Cu0.8Ni0.2WO4 nanoparticles in ammonia borane methanolysis for fast hydrogen production

Abstract

Ammonia borane (AB) methanolysis can be applied as an integrated technology for the storage and production of hydrogen with high efficiency and safety. However, the commercial applications of AB methanolysis are restricted by the high costs of noble metal–based catalysts. In this study, a series of cheap CuxNi1−xWO4 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) catalysts have been designed for AB methanolysis. Among them, heterostructured Cu0.8Ni0.2WO4 exhibits the highest turnover frequency (TOF) of 59.0 molhydrogen min−1 molcat−1, which is among the most active noble metal–free catalysts. The catalytic activity of the catalysts is well maintained after eight catalytic cycles. It is experimentally and theoretically demonstrated that electron transfer occurs on the CuWO4/NiWO4 interface in Cu0.8Ni0.2WO4 nanoparticles, leading to the formation of dual active sites on the surface of heterostructured Cu0.8Ni0.2WO4. More importantly, it is discovered that the dual active sites, namely, Cu and Ni sites, account for the adsorption and activation of AB and CH3OH, respectively, which can cooperate together to boost the catalytic activity in a significant way. The plausible mechanism for AB methanolysis has also been proposed and the scission of O-H bond is identified to be the rate-determining step. The findings in this study could serve as guidance for the creation of novel catalysts with excellent performance and low cost in AB methanolysis.