Decoupling hydrogen production from water oxidation by integrating a triphase interfacial bioelectrochemical cascade reaction

Water electrolysis to produce H 2 is a promising strategy for generating a renewable fuel . However, the sluggish-kinetics and low value-added anodic oxygen evolution reaction (OER) restricts the overall energy conversion efficiency . Herein we report a strategy of boosting H 2 production at low voltages by replacing OER with a bioelectrochemical cascade reaction at a triphase bioanode . In the presence of oxygen, oxidase enzymes can convert biomass into valuable products, and concurrently generate H 2 O 2 that can be further electrooxidized at the bioanode . Benefiting from the efficient oxidase kinetics at an oxygen-rich triphase bioanode and the more favorable thermodynamics of H 2 O 2 oxidation than that of OER, the cell voltage and energy consumption are reduced by ~0.70 V and ~36%, respectively, relative to regular water electrolysis. This leads to an efficient H 2 production at the cathode and valuable product generation at the bioanode. Integration of a bioelectrochemical cascade into the water splitting process provides an energy-efficient and promising pathway for achieving a renewable fuel .