Incorporating NiCoP Cocatalyst into Hollow Rings of ZnCo-Metal–Organic Frameworks to Deliver Pt Cocatalyst like Visible Light Driven Hydrogen Evolution Activity

Abstract

In the field of photocatalysis, metal–organic frameworks (MOFs) have emerged as potential photocatalysts owing to their well-defined and tailorable porous structures, high surface areas, and inherent semiconductor-like behavior. However, their photocatalytic H2 evolution reaction is still limited due to the higher charge recombination rates. Precious metal cocatalysts, such as Pt and Au, are used to suppress electron–hole recombination effects by forming a Schottky junction, but the high cost and scarcity of these metals limit their large-scale applications. Herein, for the first time, we have developed novel ZnCo-MOF hollow rings at room temperature and loaded it with monodispersed transition-metal phosphide (TMPs; NiCoP, FeCoP, Ni2P, CoP) nanoparticles as non-noble-metal cocatalysts for efficient visible light driven H2 evolution reaction. The as-obtained NiCoP@ZnCo-MOF composite displays significantly improved H2 production rates as compared to the parent MOF and their physical mixture and offers similar photocatalytic H2 evolution activity as compared to that of Pt@ZnCo-MOF. This is attributed to efficient n–n heterojunction charge separation and transfer, and rapid H2 evolution reaction dynamics by the reduction of activation energy by NiCoP cocatalyst. The H2 production rate of NiCoP@ZnCo-MOF is 8583.4 μmol h–1 g–1, 16 times higher than parent ZCM, and the apparent quantum yield (AQY) is 20.1% at 590 nm, which remained constant for a minimum of 18 h of repeated cycling in the H2 production without any degradation of the catalyst.