Bifunctional Electrocatalysts for Overall Water Splitting

Abstract

Electrochemical overall water splitting (OWS) is an effective approach for hydrogen production. Electrocatalysts with high intrinsic activity and stability are critical to lowering the energy barriers and accelerating rates of hydrogen and oxygen evolution reaction (HER and OER). In particular, bifunctional catalysts that can simultaneously catalyze the HER and OER have caused intensive attention because of their performance and cost advantages. Despite good progress, the improvement of intrinsic activity and durability of bifunctionalelectrocatalysts for the OWS is still a challenge in different pH conditions. This chapter firstly discusses the proposed mechanism of HER and OER in acidic, neutral, and alkaline electrolytes and the several key parameters in evaluating the OWS performance of bifunctionalelectrocatalysts. Subsequently, the OWS performance and mechanism of many novel catalysts, including noble metal-based oxides and alloys, transition metal-based oxides, chalcogenides, nitrides, and phosphides, are carefully summarized and analyzed to probe the regulation strategy of intrinsic activity. Finally, current challenges and future perspectives of bifunctionalelectrocatalysts toward OWS are discussed. The goal herein is to provide valuable strategies to design and synthesis more active OWS electrocatalysts.