Interfacial Engineering of a Carbon Nitride–Graphene Oxide–Molecular Ni Catalyst Hybrid for Enhanced Photocatalytic Activity

Abstract

Carbon nitrides (CNx) are a promising class of photocatalyst for fuel and chemical synthesis as they are nontoxic and readily synthesized at a low cost. This study reports the enhanced photocatalytic activity for simultaneous alcohol oxidation and proton reduction when graphene oxide (GO) or reduced graphene oxide (RGO) is employed as an interlayer between a cyanamide-functionalized melon-type carbon nitride (NCNCNx) and a phosphonated Ni-bis(diphosphine) H2-evolution catalyst (NiP). Introduction of the GO/RGO enhanced the activity three times, reaching a specific activity of 4655 ± 448 μmol H2 (g NCNCNx)−1 h–1 with a NiP-based turnover frequency of 116 ± 3 h–1. Mechanistic studies into this closed photoredox system revealed that the rate of electron extraction from NCNCNx is rate limiting. GO/RGO is commonly employed to improve the electron transfer dynamics on nanosecond time scales, but time-resolved photoluminescence and transient absorption spectroscopy reveal that these properties are not significan...