Bifunctional Electrocatalyst–Driven Hybrid Water Splitting for Energy‐Saving Coproduction of Green H 2 and Valuable Chemicals

Electrocatalytic water splitting to generate green H 2 with renewable energy inputs is attractive to relieve the environmental contamination and energy dilemma. Restricted by the sluggish kinetics of oxygen evolution reaction (OER) and single functionality of cathode/anode catalysts, conventional overall water splitting (OWS) suffers from high overpotentials and respective synthesis of monofunctional electrocatalysts, leading to high cost. Moreover, the generated O 2 bears low value and its possible mixing with H 2 poses safety issues. In response, hybrid water splitting (HWS) that integrates hydrogen evolution reaction (HER) with favorable oxidative upgrading reactions over bifunctional electrocatalysts can generate H 2 and value-added chemicals simultaneously with lower energy input and avoid the explosive H 2 /O 2 mixtures. Hence, this chapter focuses on the recent progress in bifunctional electrocatalyst–driven HWS for energy-saving coproduction of highly valuable chemicals and green H 2 . Firstly, the fundamentals of HER, OER, OWS, and HWS are introduced, followed by a discussion on the electrochemical reconstruction of bifunctional electrocatalysts during OWS and HWS. Next, the HWS based on bifunctional electrocatalysts is summarized, wherein the alternative oxidation reactions include upgrading of alcohol, aldehydes, amines, biomass, and plastic waste. Finally, a brief overview of current challenges and perspective for bifunctional electrocatalyst–driven HWS is discussed.