Review on porous carbon materials engineered by ZnO templates: Design, synthesis and capacitance performance

Supercapacitors (SCs), with favorable features including excellent stability, superior rate performance, and ultrahigh power densities, offer a cost-effective avenue for energy storage. Electrode materials play a decisive role in SCs. Porous carbon materials have attracted intense interests benefit from their large specific surface area, tunable porosity and high electrical conductivity. For the preparation of porous carbon materials, various hard templates and soft templates have been explored. Among those templates, nano-ZnO turn out to be good choices owing to their facile preparation, adjustable structures, inexpensive and eco-friendliness. Moreover, ZnO could be converted to Zn via carbothermal reduction and the reduced Zn could catalyze the graphitization of carbon. The resulting Zn will be evaporated which makes the template removing process unnecessary. The major purpose of this review is to elucidate the structure-directing role of ZnO templates for the construction of porous carbon nanomaterials and the capacitance performance of corresponding carbon materials. For this objective, the advance in capacitance performance of porous carbon materials synthesized by ZnO templates in the past few years are summarized. This review provides constructive ideas to the design of porous carbon with ZnO templates and applicable to other hard templates for energy storage applications.