Ce-doped self-assembled ultrathin CoOOH nanosheets as efficient oxygen evolution reaction electrocatalyst

For transition metal oxyhydroxides, morphology modification and ion doping are widely used strategies for improving the performance of water catalytic oxidation. However, how to distinguish the contribution of different factors to the oxygen evolution reaction (OER) performance is still a serious challenge. In this study, Al ions can control the morphology of CoOOH in cycle of nanosphere-nanosheet-nanosphere, and Ce-doping can significantly improve the OER activity of CoOOH, with an overpotential of 263 mV@50 mA cm(-2) and low Tafel slope of 53.74 mV dec(-1). In order to explain the above interesting experimental phenomena, detailed characterization has been carried out, such as high-resolution transmission electron microscopy (HRTEM) and electrochemical tests. At the same time, the mechanism of OER performance improvement was discussed based on electrochemical testing and density functional theory (DFT) calculations. Subsequently, the OER activities of different reactive sites, such as Al, Co, Ce, and oxygen vacancies (O-v), have been compared. As the main active center of OER, Ce ion has a minimum potential barrier of 1.71 eV. The results show that the adjustment of the adsorption intensity of the oxygen-containing species by Ce ions dominants the potential-determining step. Meanwhile, the synergistic effect of Ce and Co has also been confirmed based on the d-band theory. (C) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, morphology modification by Al ions and ion doping by Ce were used to improve the OER performance of CoOOH. Detailed characterization and mechanism studies were conducted, and the synergistic effect of Ce and Co was confirmed. Ce ions were identified as the main active center for OER.