Unveiling O2 adsorption on non-metallic active site for selective photocatalytic H2O2 production

Abstract

Photocatalytic oxygen reduction reaction (ORR) offers a promising pathway for sustainable hydrogen peroxide (H 2 O 2 ) production but faces challenges in developing catalysts with good ORR selectivity. Herein, we report that tailoring O 2 adsorption on non-metallic active sites can optimize ORR selectivity. This concept is demonstrated on three carbon nitrides with different atomic configurations: polymeric carbon nitride (PCN), lithium-poly triazine imide (Li-PTI), and sodium-poly heptazine imide (Na-PHI). Na-PHI emerges as a strong candidate for H 2 O 2 production due to the end-on adsorption mode and suitable adsorption strength with O 2 . Synthesized Na-PHI, PCN, and Li-PTI are characterized, with Na-PHI showing superior light absorption, charge carrier separation, and remarkable selectivity (92 %) for two-electron ORR. Consequently, Na-PHI achieves a high H 2 O 2 generation rate of 3.48 mmol g −1 h −1 , surpassing Li-PTI and PCN by 9.2 and 33 times, respectively. This study underscores the importance of O 2 adsorption on non-metallic active sites for selective photocatalytic H 2 O 2 generation. • Na-PHI demonstrates superior selectivity for photocatalytic H 2 O 2 production. • Optimal O 2 adsorption on non-metallic sites is key for high selectivity. • DFT calculation predicts selectivity trends of carbon nitride variants. • Advanced spectroscopies verify O 2 adsorption mode governs the selectivity.