Electrochemical Production of Formic Acid from CO 2 with Cetyltrimethylammonium Bromide‐Assisted Copper‐Based Catalysts

The electrochemical reduction of CO 2 (ERC) to valuable chemicals has attracted extensive attention. However, the relatively low selectivity and efficiency of the reaction remain challenges. In this study, Cu electrodes derived from Cu 2 O with predominant (111) facets are synthesized by cetyltrimethylammonium bromide‐assisted preparation. The optimized electrode shows a high faradaic efficiency of 90 % for HCOOH obtained by ERC at −2.0 V (vs.SCE), which surpasses most reported Cu electrodes. Based on a comprehensive analysis of the relationship between the catalytic activity and the thickness of the Cu 2 O layer, the catalytic activity of the unit active site on the Cu 2 O‐derived Cu electrodes is found to be higher than that on the blank Cu electrode. DFT calculations indicate that OCHO* would be produced preferentially over *COOH in the presence of cetyltrimethylammonium bromide (CTAB). This deduction is verified by testing of the effects of CTAB and KBr addition on HCOO − selectivity.