The development of cost-effective and active water-splitting electrocatalysts that work at mild pH is an essential step towards the realization of sustainable energy and material circulation in our society. Its success requires a drastic improvement in the kinetics of the anodic half-reaction of the oxygen evolution reaction (OER), which determines the overall system efficiency to a large extent. A simple electrochemical protocol has been developed to activate Ni electrodes, by which a stable NiOOH phase was formed, which could weakly bind to alkali-metal cations. The electrochemically activated (ECA) Ni electrode reached a current of 10 mA at 75 °C) and a mild pH of ca. 10 with excellent stability (>24 h), greatly surpassing that of the state-of-the-art NiFeOx electrodes under analogous conditions. Water electrolysis was demonstrated with ECA-Ni and NiMo, which required an iR-free overall voltage of only 1.44 V to reach 10 mA cmgeo(-2) .
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: The research reported in this work was supported by the King Abdullah University of Science and Technology (KAUST). We thank L. Stegenburga for the Raman and SEM measurements, Dr. N. Wei for the cross-sectional SEM images, Dr. D. Zhang for the TEM images, Dr. N. Wehbe for the SIMS measurement, and Dr. M. N. Hedhili for the XPS depth-profile measurements (all conducted at KAUST).