Abstract

Electrochemical water splitting is one of the promising approaches for generating hydrogen.

Developing noble metal-free electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is important to achieve efficient water-splitting.

This paper reviews the activity, stability, and durability of recently reported noble metal-free electrocatalysts such as oxides/hydroxides/(oxy)hydroxides/layered double hydroxides, sulfides, selenides, phosphides/​phosphates, nitrides, carbon-based electrocatalysts, and alloy/​B/​V/​F/​Si based electrocatalysts for the HER and OER in an alkaline environment, including the strategies used to achieve high activity and stability/​durability at a current density of ≥1000 mA cm⁻².

Moreover, this paper discusses the various promising strategies including the fabrication of nanostructured, ultrathin, porous, and nanoporous materials, preparing superaerophobic surfaces, construction of hollow structures, core – shell structures, heterostructures, heterojunctions, or Mott – Schottky heterojunctions, designing facile and/​or scalable synthesis routes, creating doping and/​or vacancies/​defects, fabricating catalysts with high valence state sites, designing medium or high-entropy alloys, and tuning the atomic packing structure, electronic structure, or conductivity to enhance the activity and stability for the HER and/​or OER.