The electrochemical method of converting CO2 into valuable products is promising both in economic and technological aspects. However, recovery is a complex multi-stage and multi-factorial catalytic process. The nature of the surface of the cathode, its structure, composition of the electrolyte, regeneration regimes significantly affect the rate of conversion of CO2 and the selectivity of the products.
The paper is devoted to the study of the comparative catalytic activity of electrodes in the reaction of the reduction of carbon (IV) oxide from aqueous 0.1 M KNCO3 solutions saturated over 30 minutes of CO2. The activity of copper cathodes of different structure (metallurgical, galvanically deposited from acidic sulfate and pyrophosphate electrolytes), as well as electrodes modified by nanostructured silver by electroplating substrate, was studied. The research is carried out by the method of cyclic voltamperovometry. Potentiostatic PY-50-1.1 was used.
The analysis of cyclic voltammetric amperograms (CVA) found that the electrode from metallurgical copper is catalytically active in relation to the cathodic reduction of CO2 from an aqueous solution. It was found that the reaction takes place at E = -1.3 V at and = 3.2 mA / ms2 with a diffusion component and a significant adsorption of the recovery products on the electrode. Restoration of carbon (IV) oxide - incomplete.
The influence of galvanic copper on the nature of the CVA has been investigated. It was found that application of galvanic copper electrode from acid sulphate and pyrophosphate solutions to the surface of electrode reduces overvoltage and increases the rate of CO2 recovery. It is shown that this is due to a change in the structure of the surface and an increase in the true area of the electrode. It is determined that the cathode recovery on such an electrode occurs at E = -1.1 and -1.5 V with a maximum current density of 3.16 and 4.2.2 mA / ms2.
A change in the nature of the CVA was observed, provided that nanoscale silver was deposited on the surface of copper electrode. It was found that this increases the catalytic activity of metal electrodes in the conversion of CO2. The influence of nanostructured silver coating obtained by galvanic substitution on the regimes of electrochemical reduction of carbon (IV) oxide from aqueous solution is investigated. It is explained that the characteristics of the cathode recovery depend on the composition and thickness of the surface layer of the electrode. It has been established that electroplating silver replacement for three seconds results in a deeper restoration of CO2, which is most pronounced in the presence of two metals, copper and silver, on the surface of the electrode.
1. Viva F. A. Electrochemical Reduction of CO2 on Metal Electrodes. Fundamentals and Applications Review // Advanced Chemistry Letters. – 2013. – Vol. 1. – P. 1–12.
2. Khezri B., Fisher A. C., Pumera M. CO2 reduction: the quest for electrocatalytic materials // J. Mater. Chem. A 5. – 2017. – Vol. 5. – P. 17 p.
3. Tuning the Catalytic Activity and Selectivity of Cu for CO2 Electroreduction in the Presence of Halides / A. S. Varela, W. Ju, T. Reier, P. Strasser // ACS Catal. – 2016. – Vol. 6. – Vol. 2136–2144.
4. Effect of nanostructured support on copper electrocatalytic activity toward CO2 electroreduction to hydrocarbon fuels / O. Baturina, Q. Lu, F. Xu, etc. // Catal. Today. – 2017. – Vol. 288. – P. 2–10.
5. Theoretical Insight into the Trends that Guide the Electrochemical Reduction of Carbon Dioxide to Formic Acid / J. S. Yoo, R. Christensen, T. Vegge // ChemSusChem. – 2016. – 2016. – Vol. 9. – P. – 358– 363.
6. An overview of CO2 electroreduction into hydrocarbons and liquid fuels on nanostructured copper catalysts / A. Abbas, M. Ullah, Q. Ali, etc. // Green Chem. Lett. Rev. – 2016. – Vol. 9. – P. 166–178.
7. An electrochemical study of carbon dioxide electroreduction on gold-based nanoparticle catalysts / V. Lates, A. Falch, A. Jordaan, etc. // Electrochimica Acta. – 2014. – Vol. 128. – P. 75–84.
8. Gold catalyst reactivity for CO2 electro-reduction: From nano particle to layer / E. B. Nursanto, H. S. Jeon, C. K., M. S. Jee, etc. // Catalysis Today. – 2016. – Vol. 260. – P. 107–111.
9. Overlayer Au-on-W Near-Surface Alloy for the Selective Electrochemical Reduction of CO2 to Methanol: Empirical (DEMS) Corroboration of a Computational (DFT) Prediction / A. Javier, J. Baricuatro, Y.-G. Kim, M. P. Soriaga // Electrocat. – 2015. – Vol. 6. – P. 493–497.
10. Electrochemical Activation of CO2 through Atomic Ordering Transformations of AuCu Nanoparticles / D. Kim, C. Xie, N. Becknell, etc. // J. Am. Chem. Soc. – 2017. – Vol. 139. – P. 8329–8336.
11. Site-Selective Growth of AgPd Nanodendrite-Modified Au Nanoprisms: High Electrocatalytic Performance for CO2 Reduction / C. Shan, E. T. Martin, D. G. Peters, J. M. Zaleski // Chem. Mater. – 2017. – Vol. 29. – P. 6030–6043.
12. Highly Active and Selective Hydrogenation of CO2 to Ethanol by Ordered Pd−Cu Nanoparticles / S. Bai, Q. Shao, P. Wang, etc. // J. Am. Chem. Soc. – 2017. – Vol. 139. – P. 6827–6830.
13. The Tunable and Highly Selective Reduction Products on Ag@Cu Bimetallic Catalysts Toward CO2 Electrochemical Reduction Reaction / Z. Chang, S. Huo, W. Zhang, etc. // J. Phys. Chem. C. – 2017. – Vol. 121. – P. 11368–11379.
14. Electrochemical CO2 reduction to CO on dendritic Ag-Cu electrocatalysts prepared by electrodeposition / J. Choi, M. J. Kim, S. H. Ahn, etc. // Chem. Eng. J. – 2016. – Vol. 229. – P. 37–44.
15. Kuntyi O. I. Elektrokhimiia ta morfolohiia dyspersnykh metaliv. – Lviv: Vyd-vo Nats. un-tu “Lvivska politekhnika”, 2008. – 208 s. 16. Kuntyi O. I. Halva-notekhnika. – Lviv: Vyd-vo Nats. un-tu “Lvivska politekhnika”, 2004. – 236 s.