Copper Phosphide-Enhanced Lower Charge Trapping Occurrence in Graphitic-C3 N4 for Efficient Noble-Metal-Free Photocatalytic H2 Evolution

Abstract

Graphitic carbon nitride (g-C3N4) fundamental photophysical processes exhibit a high frequency of charge trapping due to physicochemical defects. In this study, a copper phosphide (Cu3P) and g-C3N4 hybrid was synthesized via a facile phosphorization method. Cu3P, as an electron acceptor, efficiently captures the photogenerated electrons and drastically improved the charge separation rate to cause a significantly enhanced photocatalytic performance. Moreover, the robust and intimate chemical interactions between Cu3P and g-C3N4 offers a rectified charge-transfer channel that can lead to a higher H2 evolution rate (HRE, 277.2 μmol h–1 g–1) for this hybrid that is up to 370 times greater than that achieved from using bare g-C3N4 (HRE, 0.75 μmol h–1 g–1) with a quantum efficiency of 3.74% under visible light irradiation (λ = 420 nm). To better determine the photophysical characteristics of the Cu3P-induced charge antitrapping behavior, ultrafast time-resolved spectroscopy measurements were used to investigate the charge carriers’ dynamics from femtosecond to nanosecond time domains. The experimental results clearly revealed that Cu3P can effectively enhance charge transfer and suppress photoelectron–hole recombination.