Construction of a Noble-Metal-Free Photocatalytic H₂ Evolution System Using MoS₂/Reduced Graphene Oxide Catalyst and Zinc Porphyrin Photosensitizer

Abstract

Exploiting noble-metal-free hydrogen evolution catalysts and light-harvesting molecular photosensitizers is of huge interest for photocatalytic H2 generation. Here we report a hybrid system consisting of MoS2/reduced graphene oxide (MoS2/RGO) catalyst, Zn(II)-5,10,15,20-tetrakis(4-N-methylpyridyl)porphyrin ([ZnTMPyP]4+) photosensitizer, and triethanolamine (TEOA) as a sacrificial electron donor for photocatalytic H2 production under visible-light irradiation. Through optimizing the component proportion of MoS2/RGO catalyst, the [ZnTMPyP]4+–MoS2/RGO–TEOA photocatalytic system showed the highest H2 evolution rate of 2560 μmol h–1 g–1 at pH 7 when the ratio of MoS2 to graphene is 5:1. An apparent quantum yield of 15.2% at 420 nm was observed under optimized reaction conditions. The excellent photocatalytic result can be attributed to the improved charge carrier transfer by graphene which acts as an electron transfer bridge, as demonstrated by photoluminescence quenching and photoluminescence decay studies. It is believed that these findings would open a promising strategy to develop a noble-metal-free and visible-light-responding solar-to-H2 conversion system.