Amide Covalent Bonding Engineering in Heterojunction for Efficient Solar-Driven CO2 Reduction

Inefficient charge separation and slow interfacial reaction dynamics significantly hamper the efficiency of photocatalytic CO2 reduction. Herein, a facile EDC/NHS-assisted linking strategy was developed to enhance charge separation in heterojunction photocatalysts. Using this approach, we successfully synthesized amide-bonded carbon quantum dot-g-C3N4 (CQD-CN) heterojunction photocatalysts. The formation of amide covalent bonds between CN and CQDs in the CN-CQD facilitates efficient carrier migration, CO2 adsorption, and activation. Exploiting these advantages, the CN-CQD photocatalysts exhibit high selectivity with CO and CH4 evolution rates of 79.2 and 2.7 μmol g–1 h–1, respectively. These rates are about 1.7 and 3.6 times higher than those of CN@CQD and bulk CN, respectively. Importantly, the CN-CQD photocatalysts demonstrate exceptional stability, even after 12 h of continuous testing. The presence of the COOH* signal is identified as a crucial intermediate species in the conversion of CO2 to CO. This study presents a covalent bonding engineering strategy for developing high-performance heterojunction photocatalysts for efficient solar-driven reduction of CO2.