Synergistic Cu–Co dual active sites on anatase TiO2 for efficient ammonia borane hydrolysis

Abstract

Ammonia borane (AB) is regarded as one of the most promising candidates for chemical hydrogen storage, owing to its exceptionally high hydrogen density. Under the influence of suitable catalytic agents, AB undergoes hydrolysis, resulting in the release of hydrogen at ambient temperature. Consequently, the development of catalysts that are stable, efficient, and cost-effective has become a central focus of ongoing research. In this study, a one-pot co-reduction method was employed to synthesize a Cu–Co catalyst supported on anatase TiO₂ for the hydrolysis of AB. The catalyst demonstrated excellent performance in the hydrolysis reaction. The optimized Cu₄Co₆/TiO₂ catalyst has a turnover frequency (TOF) of 83.06 mol_H2 mol_metal⁻¹ min⁻¹ at 298 K, which outperforms most reported non-precious metal catalysts. This superior performance originates from the uniform Cu/CoO distribution on TiO₂ and their synergistic interplay. CoO facilitates H₂O adsorption and O–H bond dissociation, lowering activation energy barriers. Concurrently, metallic Cu activates AB via electron transfer to B–H σ* orbitals, weakening bonds and accelerating dehydrogenation. Moreover, the catalytic activity of the anatase TiO₂-supported catalyst is superior to that of catalysts supported on rutile TiO₂ or mixtures of anatase and rutile TiO₂, with the presence of Lewis acid sites on anatase TiO₂ being a key factor influencing its catalytic performance.