Correlation between different characterizations and improved electrochemical performances of cuprous oxide-based nanocrystals

Herein, we employed the sol–gel technique to synthesize Cu2O-based nanocrystals with Co and Na doping and co-doping, respectively. A correlation was established among several characterizations of cuprous oxide-based nanocrystals to observe their feasibility in the field of energy materials. Raman spectra typically show the formation of Cu2O, whereas, in the case of Na co-doping, it exhibits the partial presence of CuO. This form of the results prompts the conductivity of nanocrystal samples to be enhanced. According to the current–voltage measurement, the current response slightly increases as doping and co-doping concentrations rise, in which Na5% co-doped Cu2O:Co shows the optimum. Photoluminescence (PL) lifetime measurement shows increases in relative PL lifetime intensity caused by Na doping, which may be attributed to oxygen vacancies. Moreover, it is observed from the cyclic voltammetry (CV) profile that the Na and Co-doped concentration significantly enhances energy storage capability. The electrode using Na5%Cu2O:Co has shown capacitive retention of 69% after 500 GCD cycles @ 10 A g–1. This indicates the practical applicability of these developed cuprous oxide-based nanocrystals as electrode materials for improved electrochemical property. Eventually, the charge–discharge was performed at different current densities, in which specific capacitance was consistent with the CV result.