The effect of SnO-SnO₂ nanoparticle on the carbon dioxide electrochemical reduction activity on MXene/boron-doped diamond (BDD) electrode

Increasing the concentration of carbon dioxide gas (CO₂) in the atmosphere is a problem that must be addressed in modern society. A promising alternative solution to overcome this problem is to convert CO₂ into fuel and value-added chemical compounds such as formic acid (HCOOH). This study addresses this concern by electrochemical method to reduce CO₂ using a boron-doped diamond (BDD) electrode-modified SnO-SnO₂/Ti₃C₂T_x material which acts as a catalyst in improving the performance of the working electrode. The SnO-SnO₂/Ti₃C₂T_x material in this study has three various concentrationsof SnO-SnO₂/Ti₃C₂T_x 0.05 g/mL, SnO-SnO₂/Ti₃C₂T_x 0.1 g/mL, and SnO-SnO₂/Ti₃C₂T_x 0.2 g/mL, which were dropped onto the surface of the BDD electrode and characterized using cyclic voltammetry (CV), scanning electron microscope-energy dispersive X-ray (SEM-EDX), and X-ray photoelectron spectroscopy (XPS). Electroreduction of CO₂ in this study was able to produce the highest concentration of HCOOH by using a SnO-SnO₂/Ti₃C₂T_x-BDD 0.2 g/mL electrode at a reduction potential of − 0.903 V (vs. NHE). The resulting HCOOH has a concentration of 21.32 ppm with a faraday efficiency of 94.06%. The SnO-SnO₂/Ti₃C₂T_x-BDD electrode was then compared with the bare-BDD and BDD-MXene electrodes at the same reduction potential of − 0.903 V (vs. NHE). The concentration of HCOOH produced by bare-BDD was 7.63 ppm with a faraday efficiency of 63.28% and for BDD-MXene that is 9.81 ppm with a faraday efficiency of 79.87%. Thus, BDD electrode modified with SnO-SnO₂/Ti₃C₂T_x is effective to reducing the overpotential of CO₂ electroreduction and producing a higher efficiency of HCOOH.