Developments of Metal Phosphides as Efficient OER Precatalysts.

Over the last 2 years, it has been observed that metal phosphides have emerged as efficient electrocatalysts for both hydrogen and oxygen evolution reactions (HER and OER). However, while the HER has been immensely studied, the OER is limited. The chemistry in the OER is more complicated and involves irreversible surface oxidations of these materials and transforms them to their corresponding oxide/oxyhydroxide. Interestingly, these in situ changes have been widely observed generating more active catalysts with superior performance. Phosphides of Fe, Co, and Ni with different compositions have been proved as efficient catalysts for water oxidation. Considering their importance, structures, compositions, surface modifications, and also in situ transformation during electrolysis, this Perspective provides state-of-the-art views of their current developments and future prospects.