Modification of eosin Y and cobalt molecular catalyst system with reduced graphene oxide for enhanced photocatalytic hydrogen production

Abstract

By using reduced graphene oxide (RGO) as a support for the molecular cobalt catalyst (Co(bpy)₃²⁺), a new composite material RGO–Co(bpy)₃²⁺ for photocatalytic hydrogen production was prepared. The photocatalytic system, containing eosin Y (EY) as a sensitizer, Co(bpy)₃²⁺ as a catalyst, RGO as a support and triethylamine (TEA) as a sacrificial electron donor, exhibited under visible light irradiation a 2.2 times increase in hydrogen production in comparison to the system without RGO. The composites display a higher turnover number (TON), up to 185 based on Co(bpy)₃²⁺ and the highest apparent quantum yield reached 7.4% at 505 nm. Hydrogen production enhancement in the presence of RGO is attributed to the more efficient electron-transfer to the catalyst and retardation of the self-degradation path of EY radical anion mediated by RGO, which was verified using steady-state and time-resolved spectroscopy.