ALD-fabricated two-dimensional SnO2-In2O3n-n nanohybrid electrode for electrochemical supercapacitors

Abstract

Fabrication of thin-film heterostructured electrodes with thickness below 10.0 nm is of great importance for the development of high-performance electrochemical supercapacitors (ESCs) with great capabilities. This is because such electrodes with uniform thicknesses enable fast electrochemical responses during charging/discharging ascribed to their short charge and ion diffusion lengths. In this study, two-dimensional (2D) SnO2-In2O3 heterostructures with a thickness of ∼7.84 nm was fabricated on Au/SiO2/Si wafers by the atomic layer deposition (ALD) technique for ESCs application. Various spectroscopic and microscopic analyses demonstrated the formation of 2D SnO2-In2O3 heterojunction with high purity, crystallinity and homogeneous morphology. Cyclic voltammetry (CV) measurements revealed the pseudocapacitive Faradaic redox reactions with good reversibility for 2D SnO2-In2O3 heterostructure. The heterostructured electrodes demonstrated excellent super-capacitive performance with high specific capacitance (Cs) up to 1048.25 and 757 F g−1 at the scan rate and the current density of 10 mV s−1 and 12 A g−1, respectively. Accordingly, a high energy density of 51.55 Wh kg−1 is attained at 12 A g−1. The high super-capacitive performance of these heterostructures can be attributed to the improved redox activity and short ion diffusion length of the SnO2-In2O3 nanohybrid thin-film. The electrodes also demonstrated great electrochemical stability with the Cs retention of 96.15% even after 5000 charge/discharge cycles.