Porous carbonized cotton loaded with Zn–Cu–M(M=O, S) nanocomposites for electrochemical energy storage and oxygen evolution reaction

Abstract

A new strategy has been designed for enhancing the electrochemical performances of the supercapacitor and water-splitting electrodes. Hetero-structure composite electrode based on copper sulfide (CuS), zinc oxide (ZnO), and porous carbonized cotton (PCc) is prepared via vacuum thermal evaporation technology and successive ionic layer adsorption methods. Porous substrate provides plenty of active sites, which facilitates the exchange of ions/charges in the electrode processes. The composite electrode exhibits outstanding electrochemical energy storage and electrocatalytic performances. The symmetrical supercapacitor as assembled reaches a high energy density of 0.27 Wh cm−2 at the power density of 3.34 W cm−2. By optimizing the composite structure, the energy barriers of the CuS/ZnO/PCc compound are reduced obviously in oxygen evolution reaction in comparison with pure PCc or CuS/PCc. The overpotential of the sample is decreased to 337 mV (10 mA cm−2 of the loop current) compared to that of PCc (492 mV) and CuS/PCc (415 mV). This work may inspire the rational design of composite electrode materials to achieve high performance in cross-field applications.