title: In Situ Electrochemical Oxidation Tuning of Transition Metal Disulfides to Oxides for Enhanced Water Oxidation.
abstract: The development of catalysts with earth-abundant elements for efficient oxygen evolution reactions is of paramount significance for clean and sustainable energy storage and conversion devices. Our group demonstrated recently that the electrochemical tuning of catalysts via lithium insertion and extraction has emerged as a powerful approach to improve catalytic activity. Here we report a novel in situ electrochemical oxidation tuning approach to develop a series of binary, ternary, and quaternary transition metal (e.g., Co, Ni, Fe) oxides from their corresponding sulfides as highly active catalysts for much enhanced water oxidation. The electrochemically tuned cobalt-nickel-iron oxides grown directly on the three-dimensional carbon fiber electrodes exhibit a low overpotential of 232 mV at current density of 10 mA cm(-2), small Tafel slope of 37.6 mV dec(-1), and exceptional long-term stability of electrolysis for over 100 h in 1 M KOH alkaline medium, superior to most non-noble oxygen evolution catalysts reported so far. The materials evolution associated with the electrochemical oxidation tuning is systematically investigated by various characterizations, manifesting that the improved activities are attributed to the significant grain size reduction and increase of surface area and electroactive sites. This work provides a promising strategy to develop electrocatalysts for large-scale water-splitting systems and many other applications.
authors.affiliation: Department of Materials Science and Engineering and Department of Applied Physics, Stanford University , Stanford, California 94305, United States.
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.affiliation: Department of Materials Science and Engineering and Department of Applied Physics, Stanford University , Stanford, California 94305, United States.
authors.forename: Haotian
authors.initials: H
authors.lastname: Wang
authors.affiliation: Department of Materials Science and Engineering and Department of Applied Physics, Stanford University , Stanford, California 94305, United States.
authors.forename: Yuzhang
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Materials Science and Engineering and Department of Applied Physics, Stanford University , Stanford, California 94305, United States.
authors.forename: Yayuan
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Materials Science and Engineering and Department of Applied Physics, Stanford University , Stanford, California 94305, United States.
authors.forename: Jie
authors.initials: J
authors.lastname: Sun
authors.affiliation: Department of Materials Science and Engineering and Department of Applied Physics, Stanford University , Stanford, California 94305, United States.
authors.forename: Sanghan
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Materials Science and Engineering and Department of Applied Physics, Stanford University , Stanford, California 94305, United States.
authors.forename: Jang-Soo
authors.initials: JS
authors.lastname: Lee
authors.affiliation: Department of Materials Science and Engineering and Department of Applied Physics, Stanford University, Stanford, California 94305, United States; Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States.
authors.forename: Yi
authors.initials: Y
authors.lastname: Cui