Engineering Cobalt Defects in Cobalt Oxide for Highly Efficient Electrocatalytic Oxygen Evolution

• Published in: ACS catalysis Vol. 8; no. 5; pp. 3803 - 3811
• Main Authors: Zhang, Rongrong, Zhang, Yong-Chao, Pan, Lun, Shen, Guo-Qiang, Mahmood, Nasir, Ma, Yu-Hang, Shi, Yang, Jia, Wenyan, Wang, Li, Zhang, Xiangwen, Xu, Wei, Zou, Ji-Jun
• Format: Journal Article
• Language: English
• Published: American Chemical Society 04.05.2018
• Subjects: cobalt oxide; electron delocalization; electrocatalytic oxygen evolution; metal defects
• ISSN: 2155-5435; 2155-5435
• DOI: 10.1021/acscatal.8b01046

Defect engineering is an effective way to modulate the electric states and provide active sites for electrocatalytic reactions. However, most studied oxygen vacancies are unstable and susceptible under the oxygen circumstance. Here, we fabricated cobalt-defected Co3–x O4 in situ for an efficient oxygen evolution reaction (OER). XAFS and PALS characterizations show that the crystals have abundant Co vacancies and a distorted structure. DFT calculations indicate that the metal defects lead to obvious electronic delocalization, which enhances the carrier transport to participate in water-splitting reactions along the defective conducting channels and the water adsorption/activation on the catalyst surface. Therefore, cobalt-defected Co3–x O4 shows remarkably high OER activity by delivering a much lower overpotential of 268 mV@10 mA cm–2 (with a small Tafel slope of 38.2 mV/dec) for OER in KOH electrolyte, in comparison with normal Co3O4 (376 mV), IrO2 (340 mV), and RuO2 (276 mV). This work opens up a promising approach to construct electronic delocalization structures in metal oxides for high-performance electrochemical catalysts.