Two-Dimensional\nSnO₂‑ZnO Nanohybrid\nElectrode Fabricated via Atomic Layer Deposition for Electrochemical\nSupercapacitors

Abstract

Two-dimensional (2D) heterostructures of transition metal\noxides\n(TMOs) are promising candidates for high-performance electrochemical\nsupercapacitors (ESCs). Herein, sub-10 nm 2D SnO₂-ZnO heterostructures\nwere constructed on Au-modified SiO₂/Si wafers by an atomic\nlayer deposition (ALD) technique for ESC application. The cyclic voltammetry\n(CV) study revealed the pseudocapacitive-type Faradaic redox reactions\nof the 2D SnO₂-ZnO heterostructure electrode with good\nreversibility. The electrode exhibited high energy storage capability\nwith a high specific capacitance (<i>C</i>_s)\nof 538.90 F g^–1 at a scan rate and current density\nof 10 mV s^–1 and 8.0 A g^–1, respectively.\nThe corresponding energy density and the power density were 14.80\nWh kg^–1 and 2512.35 W kg^–1, respectively,\nat 8.0 A g^–1. The high energy storage capacity of\nthe heterostructure electrode can be ascribed to the combination of\nimproved infiltration and intercalation/deintercalation of electrolyte\nions induced by the nanoscale thickness and enhanced redox activity\nof the heterostructure. Furthermore, the 2D electrode displayed excellent\nelectrochemical robustness with a capacitance retention of 96.3% after\n5000 charge/discharge cycles.