Heteroatom-doped transition metal hydroxides in energy storage and conversion: a review

Abstract

High performance transition metal hydroxides (TMHs) are promising energy storage materials due to their simple and low-cost preparation process, high surface area, easy tunable composition, and so on. Heteroatom doping is an extensive approach adopted to tailor, both physically and chemically, the properties of TMHs, such as their lattice structure, electronic structure, lattice defects and diffusion behavior, so as to alter their catalytic performance for various redox reactions. Heteroatom doping can also improve the overall performance of TMH electrode materials in terms of specific capacitance and charge-discharge rate. Recently, the applications of heteroatom doping engineering in developing various TMHs/TMH-based composite materials with specific structures or functions in the fields of energy conversion and storage have been extensively explored. To this end, we review the latest developments in the heteroatom doping of TMHs in the fields of energy conversion and storage via metal doping, non-metal doping, and co-doping engineering. Then, the principles and effects of heteroatom doping in TMHs are discussed and generalized. Finally, the challenges and opportunities of heteroatom doping in TMHs are disclosed to provide insights regarding the further development of this research.