Hybrid Ce-Fe2O3/ZIF-67 Photoanode with Efficient Photoelectrochemical Water Oxidation Performance

Surface states and slow water oxidation kinetics greatly limit the photoelectrochemical (PEC) water oxidation performance of Fe2O3. To solve the above problems, coupling Fe2O3 with a passivation layer and an oxygen evolution cocatalyst, respectively, is the common method. Though this method may improve its PEC performance, this also results in a low charge-transfer efficiency caused by the interface resistance between Fe2O3 and the modification materials (passivation layer and oxygen evolution cocatalyst). Therefore, it is important to identify a multifunctional modifier material to reduce the interfacial resistance due to the presence of multiple different materials. In this work, we introduced a thin cobalt-based metal–organic framework layer (ZIF-67) as a dual-functional material that acted as both a passivation layer and a water oxidation cocatalyst for a photoanode based on Ce–Fe2O3 nanorod arrays. The ZIF-67 layer inhibited charge carrier recombination by passivating the surface states. The PEC performance was improved due to the rich Co2+ photogenerated hole-capture sites, which facilitated charge transfer and separation. As expected, the Ce–Fe2O3/ZIF-67 photoanode exhibited superior water oxidation performance, with a photocurrent of 2.07 mA cm–2 at 1.23 VRHE, which is 1.74 times higher than that of the Ce–Fe2O3 photoanode. The onset potential was negatively shifted by 71 mV. This study provides basic insights and a strategy for reducing interfacial resistance in hybrid materials.