Abstract
Water electrolysis conditions accelerate the dissolution and corrosion of electrocatalysts, changing their surface and/or bulk composition/structure from the original states. This dynamic reconstruction process redefines the catalytically active species. However, rational control of the in-situ surface reconstruction for electrocatalysts is tremendously challenging. Here, we proposed a novel redox-tuning method to precisely modulate the surface reconstruction and to favor the water oxidation activity. For a category of layered transition metal oxide (AMO2: A = alkaline metal, M = transition metal), redox of transition metal during the alkaline OER was in-situ tuned to engineer the catalyst leaching potential, manipulate the cation leaching amount, and redirect the dynamic catalyst reconstruction. Specifically, Cl doping lowered the cobalt valence state of LiCoO2 and the further OER potential for its in-situ cobalt oxidation triggering Li leaching. Operando XAFS and DFT calculations confirmed that such modulation bypassed the less favorable surface reconstruction by forming Li1-xCo2O4-type spinel structure, transforming the surface of LiCoO1.8Cl0.2 into a more catalytically-active (oxy)hydroxide phase. The proposed method could be potentially generalized to manipulate the surface reconstruction of other pre-catalysts.
Published Version
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