Photocatalytic H2 evolution integrated with selective amines oxidation promoted by NiS2 decorated CdS nanosheets

Photocatalytic hydrogen (H-2) evolution integrated with selective oxidation to produce fine chemicals is a promising strategy for solar energy conversion and storage; however, the efficiency of such coupled photocatalytic redox cycles is greatly limited by the poor surface kinetics of hydrogen evolution reaction (HER) and/or dehydrogenation reaction (DHR) on heterogenous photocatalysts. Herein, we demonstrate that the immobilization of ultrafine nickel disulfide (NiS2) nanoparticles on CdS nanosheets (NiS2/CdS) is a simple yet efficient approach to kinetic improve the surface redox reactions for H-2 production and dehydrogenative coupling of amines to imines. The NiS2 nanoparticles loaded on CdS not only function as the HER active sites to speed up charge separation and to boost H-2 release, but also enhance the adsorption of amines to facilitate the dissociation of C-H and N-H bonds to form aldimines intermediates, which are readily coupled with other amines to afford a high selectivity toward imine synthesis. Benefiting from such unique bifunctional catalytic behavior of NiS2 in proton (H+) reduction and substrate activation, NiS2/CdS exhibits a remarkable enhanced photocatalytic performance toward simultaneous production of H-2 and imines. The apparent quantum efficiency (AQE) at 420 nm is calculated to be 54.7%. This strategy using bifunctional cocatalysts to kinetic improve the surface redox reactions will have broad implications in the development of high-performance photocatalysts for integrated production of solar hydrogen and value-added solar chemicals. (C) 2021 Elsevier Inc. All rights reserved.