Interfacial bonding of hydroxyl-modified g-C3N4 and Bi2O2CO3 toward boosted CO2 photoreduction: Insights into the key role of OH groups

The development of heterogeneous photocatalysts with superior photogenerated charge separation and CO2 activation is a key challenge for artificial photosynthesis. Herein, novel hydroxyl-modified g-C3N4/flower-like Bi2O2CO3 composites (OH-CN/BOC) with covalently bonded heterointerfaces were fabricated through a direct mechanical mixing approach. The bonded samples exhibited remarkable CO2 photoreduction activity under visible light. The CO production rate of the optimized sample was 91.8, 18.2, 8.6, and 6.1 times greater than those of BOC, CN, OH-CN, and CN/BOC, respectively, reaching 26.69 μmol g-1h−1; and it remained stable after four cycles. The experimental and DFT studies reveal that the introduction of OH groups on CN leads to the chemical bonding of CN and BOC, induces stable surface oxygen vacancies (OVs) on BOC, and enhances the interaction between the catalyst with CO2 and H2O molecules, hence greatly improving the CO2 photoreduction activity of OH-CN/BOC. This work provides new insights and potential strategies for constructing high-quality interfacial heterojunctions with strong chemical bonds to facilitate the photocatalytic performance.