Metal oxide and hydroxide nanoarrays: Hydrothermal synthesis and applications as supercapacitors and nanocatalysts

The development of nanotechnology in recent decades has brought new opportunities in the exploration of new materials for solving the issues of fossil fuel consumption and environment pollution. Materials with nano-array architecture are emerging as the key due to their structure advantages, which offer the possibility to fabricate high-performance electrochemical electrodes and catalysts for both energy storage and efficient use of energy. The main challenges in this field remain as rational structure design and corresponding controllable synthesis. This article reviews recent progress in our laboratory related to the hydrothermal synthesis of metal oxide and hydroxide nanoarrays, whose structures are designed aiming to the application on supercapacitors and catalysts. The strategies for developing advanced materials of metal oxide and hydroxide nanoarrays, including NiO, Ni(OH)2, Co3O4, Co3O4@Ni–Co–O, cobalt carbonate hydroxide array, and mixed metal oxide arrays like Co3−xFexO4 and ZnxCo3−xO4, are discussed. The different kinds of structure designs such as 1D nanorod, 2D nanowall and hierarchical arrays were involved to meet the needs of the high performance materials. Finally, the future trends and perspectives in the development of advanced nanoarrays materials are highlighted.