Rational Design of Photoelectrodes with Rapid Charge Transport for Photoelectrochemical Applications.

Photoelectrode materials are the heart of photoelectrochemical (PEC) cells, which hold great promise to address global energy and environmental issues by converting solar energy into electricity or chemical fuels. In recent decades, significant research efforts have been devoted to the design and construction of photoelectrodes for the efficient generation and utilization of charge carriers to boost PEC performance. Herein, insights from a literature study on the relationship between the architecture and charge dynamics of photoelectrodes are presented. After briefly introducing the fundamental theories of charge dynamics in nanostructured photoelectrodes, the development of photoelectrode design in 1D polycrystalline nanotube arrays, 1D single-crystalline nanowire arrays, and hierarchical and mesoporous nanowire arrays is reviewed with a focus on the interplay between architecture and charge transport properties. For each design, commonly used synthetic approaches and the corresponding charge transport properties are discussed. Subsequently, the applications of these photoelectrodes in PEC systems are summarized. In conclusion, future challenges in the rational design of photoelectrode architecture are presented. The basic relationships between the architectures and charge dynamics of photoelectrode materials discussed here are expected to provide pertinent guidance and a reference for future advanced material design targeting improved light energy conversion systems.