In Situ Analysis Photogenerated Electron Transport Behavior of C Self-Doped Carbon Nitride for Photocatalytic H₂ Production

Abstract

The process of C self-doping modifies the molecular structure and electron distribution of carbon nitride, hindering the integration foreign elements. In this study, C selfdoped carbon nitride-ethylenediamine (HCN-EDA) was produced via a hydrothermal technique involving dicyanodiamine and ethylenediamine (EDA). This variant of self-doped carbon nitride exhibits a broadened visible-light absorption range, thereby improving the absorption and utilization of sunlight. HCN-EDA is characterized by significantly lower photoluminescence intensity, increased carrier lifetime, and a detectable electron paramagnetic resonance signal compared to pristine carbon nitride. Furthermore, theoretical calculations and synchronous illumination X-ray photoelectron spectroscopy confirmed that C self-doped carbon nitride with the rearranged electron distribution, leading to enhanced light responsiveness and more active electron transfer behavior. The hydrogen-evolution rate of HCN-EDA reached 52.16 mmol/(g × h), which is 63 times greater than that of pristine carbon nitride under white light from a light-emitting diode. Additionally, HCN-EDA demonstrated impressive visible light reactivity, with apparent quantum yields of 31.6% at 420 nm and 4.3% at 520 nm.