Ru-tweaking of non-precious materials: the tale of a strategy that ensures both cost and energy efficiency in electrocatalytic water splitting

Most better performing water splitting electrocatalysts are scarce, and their use increases the cost of production of H2via electrolysis. Among the best performing noble/precious metal electrocatalysts, Ru is most notable because it acts as an excellent electrocatalyst for both oxidation and reduction reactions of water responsible for the H2 production. In fact, Ru outperforms Pt/C as the state-of-the-art water reduction electrocatalyst in alkali. However, the cost-wise more expensive Ru (than Pt and Ir) could not be extensively used in water electrolysis to avoid further increase in the cost of H2 production. Recently, there has been a renewed interest in Ru and is being intensively investigated with various structural and chemical modifications at the nano-level for catalytic water electrolysis with and without other materials. However, there is no comprehensive review that summarizes and analyzes recent developments in water splitting electrocatalysts that are modulated with Ru. Hence, this review is devoted to bringing out the strategies involved in harvesting the best of water splitting electrocatalysts by Ru-tweaking. The same is also benchmarked against their performance at different conditions. Besides, a detailed note on water splitting electrocatalysis and mechanisms involving Ru are given with insights on the phenomena that make it an active interface for water electrolysis.