Enhancement in efficiency of photoelectrode through surface and structural engineering of metal oxide semiconductors

Abstract

Humans have been undergoing the fossil fuel-based industrialization, facing depletion of resource and seri-ous environmental pollution problems. As a result, the demand for sustainable and clean energy sources has been emerging as a common worldwide issue. Under such circumstances, the photoelectrochemical fuel con-version, capable of producing fuels through an electrochemical reaction using sunlight, has been attracting much of attention. In particular, the photoelectrochemical water-splitting technology for producing hydrogen fuel by inducing photo-electrolysis of water, has been widely researched as a future growth engine. However, light harvesting, charge separation and transport, and surface catalytic reactivity, which are prerequisites for achieving high photoelectrochemical conversion efficiency, cannot be satisfied by a single semiconductor. Therefore, hetero-structure engineering, joining two or more semiconductors, must be considered. Moreover, in order to realize an effective heterojunction structure, appropriate control for the surface and interface, and structure of the hetero-junction should be conducted. In this study, the structural control of $TiO_2$ into the inverse opal with extended pore was performed to effec-tively introduce the shape-controlled quantum dots as a photosensitizer. With this, the heterostructure pho-toanode with new type of sensitizer can be firstly developed. In addition, p-type $CuFeO_2$ based photocathode was successfully developed by the surface and interface engineering of heterostructures. Given the limited ap-plication of $CuFeO_2$ with superior optoelectronic properties, due to the inherent surface defect, the huge en-hancement in the photo-activity is remarkable.