Strategies and Perspectives to Catch the Missing Pieces in Energy‐Efficient Hydrogen Evolution Reaction in Alkaline Media

• Published in: Angewandte Chemie International Edition 2021-08, Vol.60 (35), p.18981-19006
• Main Authors: Anantharaj, Sengeni, Noda, Suguru, Jothi, Vasanth Rajendiran, Yi, SungChul, Driess, Matthias, Menezes, Prashanth W.
• Format: Article
• Language: English
• Subjects: Alkaline water; Anions; Catalysts; Chalcogenides; electrocatalysis; Electrocatalysts; Electrolysis; heterostructured materials; Heterostructures; Hydrogen; hydrogen evolution reaction; Hydrogen evolution reactions; Hydrogen-based energy; Hydroxides; Interfaces; Metal hydroxides; Metal oxides; Metals; Phosphides; Review; Reviews; transition metal hydroxides; Transition metals; water splitting
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.202015738

Transition metal hydroxides (M‐OH) and their heterostructures (X|M‐OH, where X can be a metal, metal oxide, metal chalcogenide, metal phosphide, etc.) have recently emerged as highly active electrocatalysts for hydrogen evolution reaction (HER) of alkaline water electrolysis. Lattice hydroxide anions in metal hydroxides are primarily responsible for observing such an enhanced HER activity in alkali that facilitate water dissociation and assist the first step, the hydrogen adsorption. Unfortunately, their poor electronic conductivity had been an issue of concern that significantly lowered its activity. Interesting advancements were made when heterostructured hydroxide materials with a metallic and or a semiconducting phase were found to overcome this pitfall. However, in the midst of recently evolving metal chalcogenide and phosphide based HER catalysts, significant developments made in the field of metal hydroxides and their heterostructures catalysed alkaline HER and their superiority have unfortunately been given negligible attention. This review, unlike others, begins with the question of why alkaline HER is difficult and will take the reader through evaluation perspectives, trends in metals hydroxides and their heterostructures catalysed HER, an understanding of how alkaline HER works on different interfaces, what must be the research directions of this field in near future, and eventually summarizes why metal hydroxides and their heterostructures are inevitable for energy‐efficient alkaline HER. This review brings out the key advancements made in the field of alkaline HER with metal hydroxides and their heterostructures and also provides a detailed and critical analysis of strategies and perspectives used with highlights on future prospects at the end.