High valence metals engineering strategies of Fe/Co/Ni-based catalysts for boosted OER electrocatalysis

Electrocatalysis for the oxygen evolution reactions (OER) has attracted much attention due to its important role in water splitting and rechargeable metal-air batteries. Therefore, designing highly efficient and low-cost catalysts for OER process is essential as the conventional catalysts still rely on precious metals. Transition metal-based compounds have been widely investigated as active OER catalysts, and renewed interest in the high valence metals engineered compounds has been achieved for superior catalytic activity and stability. However, an in-depth understanding of the construction strategies and induced effects for the high valence metals engineered catalysts is still lacking and desired. In this review, we have summarized the construction strategies of high valence metals as dopants or formed heterostructures with the iron/cobalt/nickel (Fe/Co/Ni)-based catalysts. Then the induced effects on Fe/Co/Ni-based catalysts by incorporating high valence metals, e.g., accelerating the surface reconstruction, forming amorphous structure, generating vacancies/defects, and acting as stabilizers, are highlighted. The impacts of high valence metals on OER performance are elucidated based on different elements, including molybdenum (Mo), tungsten (W), cerium (Ce), vanadium (V), chromium (Cr), manganese (Mn), niobium (Nb), zirconium (Zr). The correlations of construction strategies, induced effects, catalytic activity and OER reaction pathways are elaborated. Finally, the remaining challenges for further enhancements of OER performance induced by high valence metals are presented.