# Porous Electrodeposited Cu as a Potential Electrode for Electrochemical Reduction Reactions of CO2
## 3 Results and Discussions
### CO\({}_{2}\)RR Analysis  
Table 3 show the results of CO\({}_{2}\)RR tests of the porous Cu samples from groups A, B, and C, and the Cu foil, reported in terms of the chemical products' contents as detected by GC and NMR. Representative NMR spectra obtained from the study are shown in Figure 6. A single peak of DMSO, the internal standard, is present at 2.6 ppm. Acetate, acetone, and formate peaks are at 1.792, 2.103, and 8.363 ppm, respectively. Triple spikes at 1 ppm and quadruple spikes at 3.5 ppm represent ethanol. Acetaldehyde is detected with double spikes at 1.2 ppm. Figures 7 and 8 respectively present the rates of production  
Figure 5: Representative XPS spectra of the porous Cu electrodes from groups (**a**) A, (**b**) B, and (**c**) C, electrodeposited with 3 A/cm\({}^{2}\) for 40 s, following the CO\({}_{2}\)RR experiments. of the chemical products, and % selectivity is calculated by comparing a partial current density of a particular species to the sum of partial current densities of all detectable chemical products. Figure 6: Representative NMR spectra obtained from the CO\({}_{2}\)RR experiments, using porous Cu samples from groups (**a**) A, (**b**) B, and (**c**) C, electrodeposited with 3 A/cm\({}^{2}\) for 40 s, and (**d**) the Cu foil as electrodes. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multirow{2}{*}{**Sample**} & \multicolumn{2}{c}{**Reduction**} & \multicolumn{6}{c}{**Product (\(\mu\)mol)**} \\ \cline{2-9}  & \multicolumn{2}{c}{**Gas Product**} & \multicolumn{6}{c}{**Aqueous Product**} \\ \cline{2-9}  & **(mA/cm\({}^{2}\))** & \multicolumn{2}{c}{**H\({}_{2}\)**} & **CO** & **CH\({}_{3}\)CHO** & **CH\({}_{3}\)COO\({}^{-}\)** & **CH\({}_{3}\)COCH\({}_{3}\)** & **CH\({}_{5}\)OH** & **HCOO\({}^{-}\)** \\ \hline Cu foil & \(-0.62\) & \(3.58\) & - & - & - & \(1.03\) & \(1.61\) & \(0.95\) \\ A & \(-4.11\) & \(5.42\) & \(0.09\) & - & \(0.68\) & \(0.94\) & \(1.90\) & \(0.26\) \\ B & \(-4.74\) & \(3.40\) & \(0.08\) & \(1.08\) & \(0.49\) & \(0.70\) & \(2.56\) & \(0.19\) \\ C & \(-4.40\) & \(9.98\) & \(0.36\) & - & \(0.95\) & \(1.02\) & \(1.38\) & \(1.79\) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Amounts of chemical products and reduction current density of CO\({}_{2}\)RR obtained from different groups of copper electrodes. Figure 7: Rate of production of the chemical products of CO\({}_{2}\)RR obtained from different groups of Cu electrodes, Cu foil and the porous Cu electrodes from groups A, B, and C, electrodeposited with 3 A/cm\({}^{2}\) for 40 s.  
Generally, the mechanism pathway of the electrochemical conversion of CO2 involves adsorption of CO2 on an electrocatalytic surface and a transformation of CO2 to a radical (CO2\({}^{\bullet}\)) and subsequently to an intermediate (*CO) through electron and proton transfers. It is this intermediate that can be further transformed to different chemical products. The electrocatalysts, Cu in this case, would influence the reaction pathway, and hence the resulting intermediate species and final products, owing to their binding affinity to CO and different intermediates in the conversion processes.