Radiation-synthesis of covalent bonding heterojunctions for selective solar-driven CO2 reduction

Abstract

The low carrier concentration and sluggish internal charge migration impede the efficiency of CO₂ photoreduction in conventional catalysts. Herein, we present an efficient electron beam irradiation strategy to synthesize a carbon nitride/carbon quantum dots (ECN/CQD) heterojunction photocatalyst with an N-bridged covalent interface. This covalent bond at the ECN/CQD interface significantly accelerates the separation and migration of photogenerated charge carriers, resulting in a high concentration of surface charges. As a result, ECN/CQD demonstrates outstanding photocatalytic performance, with CO and CH₄ evolution rates of 44.5 and 0.88 μmol g⁻¹ h⁻¹, respectively, and excellent stability across eight consecutive cycles. Additionally, in situ Kelvin probe force microscopy and electrostatic force microscopy characterizations reveal the charge distribution on the catalyst surface, providing deep insights into the enhanced charge separation capabilities of the covalent bond heterojunction. This work provides an innovative approach for developing high-performance covalent bond heterojunction photocatalysts for efficient CO₂ reduction.