Recent Progress in Bifunctional Electrocatalysts for Overall Water Splitting under Acidic Conditions

Water electrolysis is an important energy conversion technology used to produce hydrogen on a mass scale. Until now, special emphasis has been placed on technology development for water electrolysis in acidic electrolytes, owing to the more facilitated hydrogen production under acidic conditions compared to alkaline water electrolysis. Among various catalyst design concepts, bifunctional catalysts capable of driving low overpotentials for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are particularly interesting, owing to the simplicity of cell system design and potential capital reduction for catalyst production. Therefore, it is intriguing to prepare bifunctional catalysts that are compatible with acidic electrolytes. In this Minireview, we introduce the recent progress in bifunctional catalysts for overall water electrolysis under acidic conditions. We briefly describe the merits of water electrolysis in acidic solution and summarize the preparation and performance of the state-of-the-art bifunctional catalysts towards both the acidic HER and OER. Finally, perspectives are provided for the current challenges and opportunities for bifunctional catalysts in acidic water electrolysis.