Layer-by-Layer Assembly of Molecular Metal Oxide Catalysts for Photoelectrochemical Water Splitting

Abstract

Artificial photosynthesis is considered one of the most promising solutions to modern energy and environmental crises. Considering that it is enabled by multiple components through a series of photoelectrochemical processes, the key to successful development of a photosynthetic device depends not only on the development of novel individual components but also on the rational design of an integrated photosynthetic device assembled from them. However, most studies have been dedicated to the development of individual components due to the lack of a general and simple method for the construction of the integrated device. In the present study, we report a versatile and simple method to prepare an efficient and stable photoelectrochemical device via controlled assembly and integration of functional components using the layer-by-layer (LbL) assembly technique. As a proof of concept, we could successfully build a photoanode for photocatalytic water oxidation by modifying the surface of various photoelectrode materials (e.g., Fe2O3, BiVO4, and TiO2) with diverse cationic polyelectrolytes and anionic polyoxometalate (molecular metal oxide) water oxidation catalysts. It was found that the performance of photoanodes was significantly improved after the deposition in terms of stability as well as photocatalytic properties, regardless of types of photoelectrodes and polyelectrolytes employed. Considering the simplicity and universal nature of LbL assembly techniques, we believe that our approach can provide a general and simple method for the design and realization of a novel photosynthetic device.