Defective-Engineered ZnO Encapsulated in N‑Doped Carbon for Sustainable 2e– ORR: Interfacial Zn–N Bond Regulated Oxygen Reduction Pathways

• Published in: ACS catalysis 2024-09, Vol.14 (17), p.12917-12927
• Main Authors: Xia, Pan, He, Tianwei, Sun, Yu, Duan, Xiaoguang, Chen, Xi, Zhu, Zhong-Shuai, Wang, Chao, Liu, Yingfei, He, Qiang, Ye, Zhihong
• Format: Article
• Language: English
• ISSN: 2155-5435; 2155-5435
• DOI: 10.1021/acscatal.4c02587

Zinc oxide (ZnO), although known for its stability and safety, has shown limited catalytic activity in the two-electron oxygen reduction reaction (2e– ORR). In this context, we synthesized a robust defective-engineered ZnO/N-doped graphene heterojunction (ZnO-NG) featuring abundant Zn–N bonds at the interface. The engineered composite exhibited a remarkable H2O2 yield of 13.1 mg h–1 cm–2 at 25 mA cm–2 with H2O2 selectivity of 85.0%, surpassing NG and ZnO counterparts. Furthermore, the exceptional long-term stability of ZnO-NG was validated through chronoamperometric measurements and 10 successive runs, highlighting its great potential for large-scale H2O2 synthesis. Density functional theory calculations and X-ray absorption near-edge structure analysis revealed that interfacial bridging N regulated the local electron distribution, transferring the unpaired electrons from Zn sites to the adjacent N/C atoms. The configuration facilitated the hydrogenation step of O2-to-OOH* and more importantly inhibited the O*-to–OH* conversion, thereby improving the selectivity in 2e– ORR toward water remediation.