The undeniable emission of anthropogenic greenhouse gases into the atmosphere remain a foremost cause of global climate changes threatening global peace ^[1-3]. A number of thermal catalysts are available that can convert carbon dioxide (CO₂) to methanol with reasonable yield and selectivity at significantly elevated temperature and pressure, using gaseous molecular hydrogen. Hydrogen has to be produced first in a separate, preceding step via water electrolysis. However, renewable energy is available primarily in the form of electrical power. Currently, the available catalysts for electrochemical reduction of CO₂ stop at CO or formic acid as the reduction products. At present, the copper is the only catalyst that can convert CO₂ to products beyond CO or formic acid to higher order alcohols.

In this study, we have developed a metal oxide catalyst that is capable of converting formic acid to C₁, C₂ and C₃ alcohols at an overall efficiency of >60%. The electrochemical characteristics were thus examined via linear sweep voltammetry and chronoamperometric (CA) methods. The formic acid reduction reaction result revealed a current density of 62 mA/cm² at 2.4 V with ohmic resistance of 5.8 Ωcm². The Tafel slope was also used to evaluate the rate-determining step for the electrochemical reaction of formic acid reduction reaction which is 580 mV/dec. Tafel values of 40 cycles were consistent with each other and with the bulk metal, therefore it can be concluded that there were perhaps no significant changes in the mechanism of reduction. However, the chronoamperometry result at 2.4 V showed the current density of 33 mA/cm²; during which methanol, ethanol and isopropanol were detected as products of formic acid reduction reactions (Fig. 1). First experiment with CO₂ electroreduction was also conducted, the findings and the reliance of the study shall be presented. This study therefore successfully developed and converted a thermal metal oxide catalyst to an electrocatalyst that could do the conversion of formic acid and CO₂ near room temperature and with water as a source of hydrogen.

[1] C. F. Shih, T. Zhang, J. Li, C. Bai, Joule 2018, 2, 1925.

[2] O. Martin, A. J. Martín, C. Mondelli, S. Mitchell, T. F. Segawa, R. Hauert, C. Drouilly, D. Curulla-Ferré, J. Pérez-Ramírez, Angew. Chemie Int. Ed. 2016, 55, 6261.

[3] L. Wang, Y. Yi, H. Guo, X. Tu, ACS Catal. 2018, 8, 90.