Branched titania nanostructures for efficient energy conversion and storage: A review on design strategies, structural merits and multifunctionalities

Abstract

Recent years have witnessed an explosive interest in branched TiO2 nanostructures (BTNs) due to their promising applications in a wide range of energy-related fields. As anode materials for solar cells (dye- or quantum dot-sensitized solar cells and perovskite solar cells), photoelectrochemical synthetic cells and energy storage devices (e.g., Li-ion batteries), BTNs with inherent nature of structural hierarchy and porosity, provide fascinating optical, electrical and electrochemical properties such as high surface area, superior light scattering and confinement, and fast electron transport. This review summarizes the recent advances in the preparation of BTNs with tailored host-guest morphologies, branches compositions and structural complexity. Their promising progress achieved in the field of energy conversion and storage is discussed. Two blossoming representatives, including the tree-like branched TiO2 nanoarrays and urchin-like branched TiO2 spheres, are highlighted to shed light on the effect of smart surface branched modification on improving the solar-to-electricity or solar-to-fuel conversion efficiencies, and increasing energy (power) densities. In addition, we also provide perspective on the new trend and future directions of novel multifunctional BTNs for next-generation energy conversion and storage devices.