Modification of copper electrode with copper nanoparticles@ reduced graphene oxide-Nile blue and its application in electrochemical CO2 conversion

A modified carbonaceous nanocomposite was prepared using Nile blue (NB)-functionalized reduced graphene oxide (rGO) (rGO-NB) decorated by copper nanoparticles (CuNPs@rGO-NB). This unique graphene oxide-based electrocatalyst was cast on a copper plate electrode and used for efficient conversion of CO2 to valuable products via electrochemical reduction in term of energy saving. The application of the represented electrocatalyst increased the electroactivity of the substrate toward the production of multicarbon species with higher selectivity. The CuNPs@rGO-NB nanocomposite was optimized for rGO, NB, and Cu nanoparticle compositions as well as the applied potential for the highest CO2 electroreduction faradaic efficiency. The modified electrocatalyst was able to reduce CO2 to value-added products (ethanol, acetic acid, formic acid, CO, and methane) with a total faradaic efficiency of about 86%. The evaluation of gas and liquid products was carried out by gas analyzer-gas chromatography, chemical oxygen demand, and gas chromatography-mass spectrometry techniques. The best results were observed at the potential of -1.0 V vs. Ag/AgCl, rGO amount of 0.5 mg mL(-1), NB and a copper concentration of 15 and 10 mM, respectively. The outstanding electroactivity of the nanocomposite could be promising in terms of electroconversion of CO2 to useful products and facing environmental challenges. (C) 2020 Elsevier Ltd. All rights reserved.