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 Li_1-xCo₂O₄-type spinel structure, transforming the surface of LiCoO_1.8Cl_0.2 into a more catalytically-active (oxy)hydroxide phase. The proposed method could be potentially generalized to manipulate the surface reconstruction of other pre-catalysts.

References

1. Wang, J.; Gao, Y.; Kong, H.; Kim, J.; Choi, S.; Ciucci, F.; Hao, Y.; Yang, S.; Shao, Z.; Lim, J., Non-precious-metal catalysts for alkaline water electrolysis: operando characterizations, theoretical calculations, and recent advances. Chemical Society Reviews 2020, (49), 9154-9196.

2. Wang, J.; Kim, S.-J.; Liu, J.; Gao, Y.; Choi, S.; Han, J.; Shin, H.; Jo, S.; Kim, J.; Ciucci, F.; Kim, H.; Li, Q.; Yang, W.; Long, X.; Yang, S.; Cho, S.-P.; Chae, K. H.; Kim, M. G.; Kim, H.; Lim, J., Redirecting dynamic surface restructuring of a layered transition metal oxide catalyst for superior water oxidation. Nature Catalysis 2021, 4 (3), 212-222.