Oxygen vacancy-enriched bilayer flower-like structure of ZnO&NiO@C-ZnO nanorod arrays on carbon cloth with improved eletrochemical performance

Herein, flower-like ZnO&NiO@C-coated ZnO nanorod arrays based on carbon cloth (ZnO&NiO@C-ZnO NRs/CC) is designed based on ZnO&NiO nanosheets epitaxially grown on C-ZnO nanorod arrays by electrochemical deposition and chemical reaction method. Notably, the ZnO&NiO@C-ZnO NRs/CC possess significant synergistic effect of ZnO and NiO, 3-dimension scaffolding of C-ZnO NRs, and importantly, abundant oxygen vacancy defects, thus rendering them deliver a specific capacity of 1001.5 F g⁻¹ at 3 A g⁻¹ current density and maintains 92.33 % retention after 20,000 cycles in 1 M KOH electrolyte. Further, theoretical calculation certifies that the abundant oxygen vacancies in interface model of ZnO and NiO are favor of rapid electron transfer, ion diffusion, and adsorption/desorption between electrolyte ions and the surface of active material. Moreover, an all-solid symmetric supercapacitor is also fabricated using the ZnO&NiO@C-ZnO NRs/CC and gel electrolyte, which shows the energy density of 27.5 Wh kg⁻¹ at the power density of 4.5 kW kg⁻¹, and ultrahigh capacitance retention of 102.83 % after 10,000 cycles. These research results demonstrate that the design of nanomaterials with numerous oxygen vacancies, unique flower-like structure, and synergistic effect of ZnO and NiO may open up new opportunities for the development of high-performance supercapacitors.