Intercalated Iridium Diselenide Electrocatalysts for Efficient pH‐Universal Water Splitting

Abstract Developing bifunctional catalysts for both hydrogen and oxygen evolution reactions is a promising approach to the practical implementation of electrocatalytic water splitting. However, most of the reported bifunctional catalysts are only applicable to alkaline electrolyzer, although a few are effective in acidic or neutral media that appeals more to industrial applications. Here, a lithium‐intercalated iridium diselenide (Li‐IrSe 2 ) is developed that outperformed other reported catalysts toward overall water splitting in both acidic and neutral environments. Li intercalation activated the inert pristine IrSe 2 via bringing high porosities and abundant Se vacancies for efficient hydrogen and oxygen evolution reactions. When Li‐IrSe 2 was assembled into two‐electrode electrolyzers for overall water splitting, the cell voltages at 10 mA cm −2 were 1.44 and 1.50 V under pH 0 and 7, respectively, being record‐low values in both conditions.