The study of photogenerated charge behavior and photocatalytic hydrogen evolution on g-C3N4 decorated with PtCox bimetal

Abstract

Exploration of unique and useful photocatalysts is of great importance to address the energy and environmental concerns by utilizing solar energy. Graphite carbon nitride (g-C3N4) is regarded as an effective photocatalyst for the photocatalytic hydrogen evolution. However, the hydrogen production rate of bare g-C3N4 is almost negligible due to a quick recombination of photogenerated electrons and holes. Herein, we modified g-C3N4 with PtCox cocatalyst to accelerate the transfer of photogenerated charges and to further restrain the recombination of photogenerated electrons and holes in bulk. As a result, the superior electrical conductivity of PtCox promotes the migration of photogenerated charges and further improves the separation efficiency of photogenerated charges for PtCox/g-C3N4 photocatalyst, meanwhile, the low overpotential of PtCox accelerates the reaction kinetics. The enhanced photocatalytic activity of 2.5PtCox results in hydrogen evolution rate of 11.9 mmol h−1 g−1. PtCox/g-C3N4 photocatalyst was characterized by systematically examining the photogenerated charges behavior through studying surface photovoltage, transient surface photovoltage, surface photocurrent, and photoacoustic technology. Based on the obtained results, a photocatayltic mechanism is proposed and discussed in detail. This work improves the photocatalytic performance of g-C3N4 and contributes to a theoretical knowledge for the fabrication of future cocatalyst/photocatalyst systems.