Electrocatalytic oxygen evolution reaction (OER) has been recognized as the bottleneck of overall water splitting, which is a promising approach for sustainable production of H2. Transition metal (TM) hydroxides are the most conventional and classical non-noble metal-based electrocatalysts for OER, while TM basic salts [M2+(OH)2-x(Am−)x/m, A = CO32−, NO3−, F−, Cl−] consisting of OH− and another anion have drawn extensive research interest due to its higher catalytic activity in the past decade. In this review, we summarize the recent advances of TM basic salts and their application in OER and further overall water splitting. We categorize TM basic salt-based OER pre-catalysts into four types (CO32−, NO3−, F−, Cl−) according to the anion, which is a key factor for their outstanding performance towards OER. We highlight experimental and theoretical methods for understanding the structure evolution during OER and the effect of anion on catalytic performance. To develop bifunctional TM basic salts as catalyst for the practical electrolysis application, we also review the present strategies for enhancing its hydrogen evolution reaction activity and thereby improving its overall water splitting performance. Finally, we conclude this review with a summary and perspective about the remaining challenges and future opportunities of TM basic salts as catalysts for water electrolysis.

Oxygen evolution reaction (OER) is the anodic half‐reaction for crucial energy devices, such as water electrolysis, metal–air battery, and electrochemical CO2 reduction. Fe‐based materials are recognized as one of the most promising electrocatalysts for OER because of its extremely low price and high activity. In particular, iron oxyhydroxide (FeOOH) is not only highly active toward OER, but also widely accepted as the true active species of Fe‐based OER electrocatalysts for plenty of Fe‐based materials are converted into FeOOH during OER test. Herein, the recent advances of FeOOH‐based nano‐structure and its application in OER are reviewed. The relationship between FeOOH structure and its catalytic performance, followed by the introduction of current strategies for enhancing the OER activity (i.e., crystalline phase engineering, element doping, and construction of hybrid materials) is mainly focused. Finally, a summary and perspective about the remaining challenges and future opportunities in this area and further the design of Fe‐based OER electrocatalysts are provided.

Metal–organic frameworks (MOFs) are a class of porous two- or three-dimensional infinite structure materials consisting of metal ions or clusters and organic linkers, which are connected via coordination bonds [...]