 highlights a bimetallic lanthanum nickel oxysulfide based on a law 202s prototype was developed, as a pre-catalyst for the electrochemical alkaline oxygen evolution reaction OER. The in situ, ex situ, and theoretical investigations demonstrated that the pre-catalyst underwent a deep OER driven reconstruction into a porous hetero structure where NIOOH nanodomains were uniformly separated and confined by law OH3 barrier. Oxyanion, so 4 2 minus, was steadily adsorbed on the surface of this in situ reconstructed NIOOH slash law OH3 hetero structure, enabling it for enhanced OER activity and durability. This article was authored by Kai Yu, Hong Yuan Yang, Hao Zhang, and others.