Self-Reconstruction of Single-Atom-Thick A Layers in Nanolaminated MAX Phases for Enhanced Oxygen Evolution

M(n+1)AX(n) (MAX) phases are a family of nanolaminated ternary carbide/nitride, which are generally investigated as high-safety structural materials, but their direct applications on electrocatalysis is still far from reality. Here, it is shown that by taking the advantages of self-reconstruction, a unique class of MAX phases of V-2(Sn, A)C (A = Ni, Co, Fe) can be adopted as efficient catalysts for oxygen evolution reaction (OER). The specific single-atomic-thick (Sn, A) layers within V-C networks in V-2(Sn, A)C are highly flexible to react with electrolyte. As a result, the V-2(Sn, Ni)C (VSNC) can maintain bulk crystalline structure, and merely encounter surface reconstruction to generate Ni-based oxyhydroxide accompanying with the self-doping of V and Sn elements under alkaline OER condition. The surface-reconstructed VSNC exhibits significantly enhanced OER performance to that of reconstructed Ni nanopowder and V2SnC. Density functional theory simulations indicate that the doping of Sn/V into gamma-NiOOH leads to the change of reaction pathway of alkaline OER, while the introduction of V can reduce the reaction barrier to facilitate the OER process. This study exhibits a new functionality of a unique MAX phase toward OER, which puts forward the potential applications of MAX phase materials in electrocatalysis and beyond.