Developing Ni single-atom sites in carbon nitride for efficient photocatalytic H2O2 production
Xu Zhang, Hui Su, Peixin Cui, Yongyong Cao, Zhenyuan Teng, Qitao Zhang, Yang Wang, Yibo Feng, Ran Feng, Jixiang Hou, Xiyuan Zhou, Peijie Ma, Hanwen Hu, Kaiwen Wang, Cong Wang, Li‐Yong Gan, Yunxuan Zhao, Qinghua Liu, Tierui Zhang, Kun Zheng
Abstract
Abstract Photocatalytic two-electron oxygen reduction to produce high-value hydrogen peroxide (H 2 O 2 ) is gaining popularity as a promising avenue of research. However, structural evolution mechanisms of catalytically active sites in the entire photosynthetic H 2 O 2 system remains unclear and seriously hinders the development of highly-active and stable H 2 O 2 photocatalysts. Herein, we report a high-loading Ni single-atom photocatalyst for efficient H 2 O 2 synthesis in pure water, achieving an apparent quantum yield of 10.9% at 420 nm and a solar-to-chemical conversion efficiency of 0.82%. Importantly, using in situ synchrotron X-ray absorption spectroscopy and Raman spectroscopy we directly observe that initial Ni-N 3 sites dynamically transform into high-valent O 1 -Ni-N 2 sites after O 2 adsorption and further evolve to form a key *OOH intermediate before finally forming HOO-Ni-N 2 . Theoretical calculations and experiments further reveal that the evolution of the active sites structure reduces the formation energy barrier of *OOH and suppresses the O=O bond dissociation, leading to improved H 2 O 2 production activity and selectivity.