Non-precious metal electrocatalysts for acidic water splitting: Progress, challenges, and perspectives

Electrocatalytic water splitting can be driven by electricity to convert water into hydrogen (H₂) and oxygen (O₂), and is considered a critical bridge for clean energy conversion, with the key being the exploration of efficient and stable electrocatalysts. Compared to precious metal electrocatalysts (PMEs), non-precious metal electrocatalysts (NPMEs) inherently offer a cost advantage, and some NPMEs exhibit the same stability and low overpotential as PMEs in acidic electrocatalytic water splitting. In recent decades, a lot of studies has been done on the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) of NPMEs in acidic media. We first summarized the basic principles of OER and HER, and then reviewed the latest developments in NPMEs for HER and OER. Subsequently, the advantages and disadvantages of various types of NPMEs under acidic conditions were analyzed, and their performance in OER, HER, and overall water splitting was compared. Based on this, we summarized cutting-edge approaches to enhance the electrocatalytic performance of NPMEs, including nanostructure design, heteroatom doping, and composite carrier strategies. Finally, we analyzed the current hurdles and the future research avenues for NPMEs. This review helps to understand the basic principles and research progress of electrocatalytic water splitting in acidic media, and clarifies the future direction of this field.