Atomic Layer Deposition of ZnO on CuO Enables Selective and Efficient Electroreduction of Carbon Dioxide to Liquid Fuels

Abstract

Electrochemical reduction of carbon dioxide, if powered by renewable electricity, could serve as a sustainable technology for carbon recycling and energy storage. Among all the products, ethanol is an attractive liquid fuel. However, the maximum faradaic efficiency of ethanol is only ≈10 % on polycrystalline Cu. Here, CuZn bimetallic catalysts were synthesized by in situ electrochemical reduction of ZnO‐shell/CuO‐core bi‐metal‐oxide. Dynamic evolution of catalyst was revealed by STEM‐EDS mapping, showing the migration of Zn atom and blending between Cu and Zn. CuZn bimetallic catalysts showed preference towards ethanol formation, with the ratio of ethanol/ethylene increasing over five times regardless of applied potential. We achieved 41 % faradaic efficiency for C2+ liquids with this catalyst. Transitioning from H‐cell to an electrochemical flow cell, we achieved 48.6 % faradaic efficiency and −97 mA cm−2 partial current density for C2+ liquids at only −0.68 V versus reversible hydrogen electrode in 1 m KOH. Operando Raman spectroscopy showed that CO binding on Cu sites was modified by Zn. Free CO and adsorbed *CH3 are believed to combine and form *COCH3 intermediate, which is exclusively reduced to ethanol.

Simultaneously Regulating the Ion Distribution and Electric Field to Achieve Dendrite‐Free Zn Anode

“…The diminished Cu 2+ peaks (Figure 2b) and the appearance of the Zn signal (Figure S5, Supporting Information) in the XPS spectra of CM@CuO@Zn in the initial deposition process also indicate the reduction reaction of CuO and the simultaneous Zn nucleation. [ 11 ] The Cu 2p signal is almost undetectable as Zn continues to grow on current collectors (Figure S6, Supporting Information). As seen from Figure S7 (Supporting Information), the XRD patterns of the products show the existence of Cu and Zn and extra peaks related to Cu‐Zn alloy (CuZn 5 ) are consistent with our previous work.…”

Promoting CO2 electroreduction on CuO nanowires with a hydrophobic Nafion overlayer

“…Powder X-ray diffraction (XRD) measurements confirm that the crystalline phase of the sample before Nafion modification is CuO 26 (PDF#80-0076) mixed with a small amount of Cu 2 O (PDF#78-2076), which might result from the diffusion of Cu atoms from the substrate into CuO during the annealing process (Fig. 2a).…”

“…3 M KOH for 600 s, followed by thermal annealing at 180°С in air for 60 minutes. 26 To prepare the Nafion modified electrode, 40 µL of ethanolic dispersion of Nafion (20, 60, and 180 µL in 1 mL ethanol) was carefully dropcast onto both sides of the CuO nanowire electrode (10 × 10 mm) twice (Fig. 1).…”

Copper Sulfide as the Cation Exchange Template for Synthesis of Bimetallic Catalysts for CO2 Electroreduction

“…14 A second approach is to change the local electronic structure of Cu by alloying with the other elements in order to tune the binding strength towards intermediates. [15][16][17][18][19] For example, Ag atoms in the bimetallic Cu-Ag catalyst create a diversity of binding configurations compared with pure Cu that facilitates the production of ethanol. 20 The compressive surface strain induced by Ag reduces the H* adsorbates, leading to the selective suppression of HER and favors the production of multicarbon oxygenates.…”