Redirecting dynamic surface restructuring of a layered transition metal oxide catalyst for superior water oxidation

Rationally manipulating the in situ formed catalytically active surface of catalysts remains a tremendous challenge for a highly efficient water electrolysis. Here we present a cationic redox-tuning method to modulate in situ catalyst leaching and to redirect the dynamic surface restructuring of layered LiCoO_2–xCl_x (x = 0, 0.1 or 0.2), for the electrochemical oxygen evolution reaction (OER). Chlorine doping lowered the potential to trigger in situ cobalt oxidation and lithium leaching, which induced the surface of LiCoO_1.8Cl_0.2 to transform into a self-terminated amorphous (oxy)hydroxide phase during the OER. In contrast, Cl-free LiCoO₂ required higher electrochemical potentials to initiate the in situ surface reconstruction to spinel-type Li_1±xCo₂O₄ and longer cycles to stabilize it. Surface-restructured LiCoO_1.8Cl_0.2 outperformed many state-of-the-art OER catalysts and demonstrated remarkable stability. This work makes a stride in modulating surface restructuring and in designing superior OER electrocatalysts via manipulating the in situ catalyst leaching. [Figure not available: see fulltext.].