MnO2-based nanostructured materials for various energy applications

Among many types of low-dimensional inorganic nanostructures, nanostructured MnO2 provides unique advantages in designing and synthesizing efficient electrode and catalyst materials for novel energy storage technologies. The low cost, high redox potential, theoretically high energy storage capacity, environmentally friendliness, and rich deposits provide MnO2 nanomaterials with a high level of economic feasibility for various renewable energy-related applications, like electrodes for metal-ion batteries/metal–sulfur batteries/metal–O2 batteries/supercapacitors and electrocatalysts for oxygen evolution/oxygen reduction/CO2 reduction/N2 fixation. In this review, a wide spectrum of the energy-related applications of diverse nanostructured MnO2 materials is systematically surveyed along with versatile synthetic methods of these metal oxides and chemical design strategies to improve their electrochemical functionalities. Future research perspectives for nanostructured MnO2 materials are provided to offer insightful directions for the exploration of next-generation energy storage/conversion systems.