Influência de tratamento térmico no desempenho eletrocatalítico de eletrodos de cobre na redução de CO2

The electrocatalytic reduction of CO2into organic molecules (C1 and C2) is an alternative with great potential for climate change The electrocatalytic reduction of CO2 into organic molecules (C1 and C2) is an alternative with great potential for climate change mitigation, besides the possibility of renewable energy production.1In this work we report theinvestigation of the effect ofheat treatment at bulk Cu electrodes towardsthe electroreduction of CO2. The Cu plates were electropolished in H3PO4(electrode 1)and further treated at 500°C for 12h(electrode 2).The X-raydiffraction pattern of Cu-electropolished (Fig. 1a) exhibited peaks that can be assigned to cubic phase of metallic Cu (PDF: 85-1326), while the Cu-calcined exhibitedpeaks than can be indexed to metallic Cu and cubic phase of Cu2O (PDF: 65-3288). The activity of Cu electrodes towardsCO2electroreduction was probed by cyclic voltammetry in aqueous KHCO3(0.1 M) saturated with CO2(Fig. 1b).The Cu-calcinedelectrodeshowed a lower overpotential value, besides a cathodic current higher than to of theCu-electropolishedone. In order to confirm the CO2electroreduction was performed a chronoamperometry at -1.3 V (vs Ag/AgCl) for 16h, an aliquot was analyzed by high-performance liquid chromatography (Fig. 1c).Both electrodes formed only formate (HCOO-) in liquid phase, confirming that the electrodes were active towardsCO2reduction.The Cu-calcined electrode produced 482 ppm of HCOO-, while the Cu-electropolished electrode produced 23 ppm. Further, the Cu-calcined electrode exhibited a Faradaic efficiency (FE) of approximately 39%, while the Cu-electropolished exhibited a FE of 27%for CO2to HCOO-conversion. Finally, it can be concludedthat the heat treatment on Cu electrode increase its electrocatalytic activity and FE for CO2electroreduction.Probably due to increase in roughness of electrode and the presence of different active site (generated by reduction of Cu+to Cu).2However, additional investigations to evaluate the key parameters responsible to this increase andtheanalysis of gaseous products formed are in progress.