Two-Dimensional SnO<sub>2</sub>-ZnO Nanohybrid Electrode Fabricated via Atomic Layer Deposition for Electrochemical Supercapacitors
Nasrin Siraj Lopa, Mohammad Karbalaei Akbari, Di Wu, Francis Verpoort, Serge Zhuiykov
Abstract
Two-dimensional (2D) heterostructures of transition metal oxides (TMOs) are promising candidates for high-performance electrochemical supercapacitors (ESCs). Herein, sub-10 nm 2D SnO 2 -ZnO heterostructures were constructed on Au-modified SiO 2 /Si wafers by an atomic layer deposition (ALD) technique for ESC application. The cyclic voltammetry (CV) study revealed the pseudocapacitive-type Faradaic redox reactions of the 2D SnO 2 -ZnO heterostructure electrode with good reversibility. The electrode exhibited high energy storage capability with a high specific capacitance ( C s ) of 538.90 F g –1 at a scan rate and current density of 10 mV s –1 and 8.0 A g –1, respectively. The corresponding energy density and the power density were 14.80 Wh kg –1 and 2512.35 W kg –1, respectively, at 8.0 A g –1 . The high energy storage capacity of the heterostructure electrode can be ascribed to the combination of improved infiltration and intercalation/deintercalation of electrolyte ions induced by the nanoscale thickness and enhanced redox activity of the heterostructure. Furthermore, the 2D electrode displayed excellent electrochemical robustness with a capacitance retention of 96.3% after 5000 charge/discharge cycles.