Synergistic Defect Sites and CoO<sub><i>x</i></sub> Nanoclusters in Polymeric Carbon Nitride for Enhanced Photocatalytic H<sub>2</sub>O<sub>2</sub> Production
Jixiang Hou, Kaiwen Wang, Xu Zhang, Yang Wang, Hui Su, Chenyu Yang, Xiyuan Zhou, Wenning Liu, Hanwei Hu, Jiaxing Wang, Chen Li, Peijie Ma, Rui Zhang, Zhen Wei, Zaicheng Sun, Qinghua Liu, Kun Zheng
Abstract
The photocatalytic two-electron O 2 reduction reaction (2e – ORR) for high-value hydrogen peroxide (H 2 O 2 ) production is attracting widespread attention as a green and promising research pathway. Despite multiple optimization strategies, the current 2e – ORR systems remain constrained by photogenerated carrier recombination and slow O 2 reduction kinetics. Therefore, a refined photocatalyst design is urgently needed to overcome these constraints, enabling enhanced H 2 O 2 activity and deeper exploration of reaction mechanisms. Here, we design surface defect sites (N vacancies) and oxygen-affine CoO x nanoclusters on polymeric carbon nitride (CN) to break through the above limitations for enhanced photocatalytic H 2 O 2 production. The introduction of N vacancies significantly enhances the photogenerated carrier separation, and highly active CoO x nanoclusters optimize the surface reaction process from O 2 to H 2 O 2, synergistically improving the activity and selectivity of H 2 O 2 production. The designed photocatalyst (CoO x -NvCN) achieves a H 2 O 2 production rate of 244.8 μmol L –1 h –1 in pure water, with an apparent quantum yield (AQY) of 5.73% at 420 nm and a solar-to-chemical energy conversion (SCC) efficiency of 0.47%, surpassing previously reported CN-based photocatalysts. Importantly, experiments and theoretical calculations reveal that N vacancies optimize the photoelectronic response characteristics of the CN substrate, while the CoO x nanoclusters promote O 2 adsorption and activation, reducing the formation energy barrier for crucial intermediate *OOH, thereby accelerating H 2 O 2 generation. This work provides a feasible approach to the photocatalyst design strategy that simultaneously facilitates photogenerated carrier separation and effective active sites for high-performance H 2 O 2 production.