The performance of energy materials hinges on the presence of structural defects and heterogeneity over different length scales, as well as surface properties. We propose a complementary approach based on Kelvin probe measurements and photoconductive atomic force microscopy. Herein, we present the correlation between morphological and functional heterogeneity in bismuth vanadate, a promising metal oxide photoanode for photoelectrochemical water splitting. We demonstrate that contrast in mapping electrical conductance depends on charge transport limitations. Using temperature and illumination intensity-dependent current–voltage spectroscopy, we find that the transport mechanism in bismuth vanadate can be attributed to space charge-limited current in the presence of trap states. In addition, we elucidate the effects of oxygen and water surface adsorption on band alignment, interfacial charge transfer, and charge-carrier transport on this material. We provide insights on chemical transformations that occur on photoactive materials, and into how local functionality affects the macroscopic performance.

Understanding nanoscale and interfacial charge transport in water splitting photoanodes

2019 Spring National Meeting

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