Recent progress and perspective of cobalt-based catalysts for water splitting: design and nanoarchitectonics

Water splitting, which encompasses the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), is a promising approach for large-scale and sustainable production of hydrogen (H2) and oxygen (O2). However, the water splitting kinetics is slow, and noble metal catalysts such as platinum (Pt), ruthenium (IV) oxide (RuO2)/ iridium (IV) oxide (IrO2) are typically required to improve water splitting efficiency. Therefore, non-noble metals such as cobalt (Co)-based catalysts with a lower cost, natural abundance, catalytic performance comparable to that of noble metal catalysts, and good structural stability are highly desirable as substitutes for the expensive and environmentally scarce noble metals in energy applications. In this review, recent progress pertaining to the advance and development of different types of Co-based catalysts is reviewed. In addition, the fundamental mechanisms of water electrolysis and ways to improve the HER/OER activity are discussed. Finally, the present challenge and prospective for the future development of water splitting electrocatalysts are discussed.