Bias‐Free Photoelectrochemical Water Oxidation Coupled with Electrochemical Oxygen Reduction Reaction via Fe‐Based Electrodes with Long‐Term Operation
Haojie Chen, Zehua Gao, Nhat Truong Nguyen, Zilong Li, Rui‐Ting Gao, Limin Wu, Lei Wang
Abstract
Abstract Photoelectrochemistry (PEC) is a green and sustainable approach in the synthesis of H 2 O 2 , depending on the semiconductor to initiate two‐electron water oxidation into hydrogen peroxide (H 2 O 2 ). However, the photoanodes generally have sluggish charge transfer and a limited number of active sites, which limit the yield and faradaic efficiency (FE) for the production of H 2 O 2 . Herein, Ti‐doped Fe 2 O 3 photoanode with the modification of ZnO passivation layer (ZnO/Ti‐Fe 2 O 3 ) for PEC H 2 O 2 production is developed. The optimized photoanode has shown a high FE and selectivity for two‐electron water oxidation, achieving a yield approaching 0.56 µmol min −1 cm −2 at 1.23 V RHE and an average FE over 80% in the potential range from 1.0 to 1.6 V RHE . Impressively, an unassisted PEC system is designed to generate H 2 O 2 at the ZnO/Ti‐Fe 2 O 3 photoanode while performing an oxygen reduction reaction (ORR) at the Fe(Co)‐NC cathode. The integrated system enables the average PEC H 2 O 2 production rate of 0.275 µmol min −1 cm −2 without applying any additional bias. Moreover, an unassisted PEC cell obtains a long‐term stability of 100 h. This work demonstrates new possibilities in designing efficient and stable PEC assemblies using low‐cost earth‐abundant materials for light‐driven catalysis.