Hybrid Ce-Fe 2 O 3 /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 Fe 2 O 3 . To solve the above problems, coupling Fe 2 O 3 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 Fe 2 O 3 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-Fe 2 O 3 nanorod arrays. The ZIF-67 layer inhibited charge carrier recombination by passivating the surface states. The PEC performance was improved due to the rich Co 2+ photogenerated hole-capture sites, which facilitated charge transfer and separation. As expected, the Ce-Fe 2 O 3 /ZIF-67 photoanode exhibited superior water oxidation performance, with a photocurrent of 2.07 mA cm -2 at 1.23 V RHE , which is 1.74 times higher than that of the Ce-Fe 2 O 3 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.