Coupled Copper–Zinc Catalysts for Electrochemical Reduction of Carbon Dioxide

Abstract

A catalyst plays a key role in the electrochemical reduction of CO2 to valuable chemicals and fuels. Hence, the development of efficient and inexpensive catalysts has attracted great interest from both the academic and industrial communities. In this work, low‐cost catalysts coupling Cu and Zn are designed and prepared with a green microwave‐assisted route. The Cu to Zn ratio in the catalysts can be easily tuned by adjusting the precursor solutions. The obtained Cu–Zn catalysts are mainly composed of polycrystalline Cu particles and monocrystalline ZnO nanoparticles. The electrodes with optimized Cu–Zn catalysts show enhanced CO production rates of approximately 200 μmol h−1 cm−2 with respect to those with a monometallic Cu or ZnO catalyst under the same applied potential. At the bimetallic electrodes, ZnO‐derived active sites are selective for CO formation and highly conductive Cu favors electron transport in the catalyst layer as well as charge transfer at the electrode/electrolyte interface.

Sn-Decorated Cu for Selective Electrochemical CO2 to CO Conversion: Precision Architecture beyond Composition Design

“…Strikingly, the dendrite morphology exhibits very high faradaic efficiency of above 85% for CO evolution at potentials between -0.7 V and -1.0 V, peaking even at 91% at -0.7 V. The faradaic efficiency for H 2 evolution remains below 20% even at high overpotentials, resulting in a high CO partial current density of up to 11.5 mA•cm -2 at -1.1 V, 170% of the maximum value measured for the particle morphology. Moreover, this is the first study reporting a CO partial current density higher than 10 mA•cm -2 for the Cu-Sn system [2][3][6][7][8][9] . The situation is very different for the particle morphology in Fig.…”

“…The highest selectivity for CO production is achieved at an optimal Cu/Sn ratio at the catalyst surface 3-4, 6, 8 . High CO faradaic efficiencies above 90 % were reported at low-to-moderate overpotentials resulting in CO partial current densities of 1.9 to 4.6 mA•cm -2 at -0.7 V (vs. RHE) 3,6,8 . However, with the improvement of the CO 2 RR kinetics, the electrode surface encounters CO 2 mass-transport limitations [16][17] .…”

“…The CO 2 RR to carbon monoxide (CO) or formate/formic acid (HCOO -/HCOOH) are considered to be the economically most favorable processes to compete with conventional production routes 1 . High selectivity and high stability for the CO 2 RR to CO in aqueous electrolyte were reported for bimetallic Cu-Sn catalysts [2][3][4][5][6][7][8][9] . Due to the lower cost of Cu and Sn compared to Au or Ag, Cu-Sn catalysts are better suited for large-scale deployment compared to e.g.…”

Heterogeneous Electrocatalysts for CO2 Reduction to Value Added Products

“…The CO 2 RR on Au and Ag is characterized by low overpotentials, excellent selectivity and high activity [18-20, 30, 44]. On contrast, Zn shows relatively higher overpotentials, lower activity and moderate-to-high selectivity [8,21].…”

“…Firstly, this method can use green chemicals as electrolytes and electricity from renewable energy sources, thus not contributing to new CO 2 emissions while transforming it [6]. Secondly, the products and conversion rates can be tuned by utilizing different catalysts and applying various potentials [7,8]. Finally, the electrolyzer and electrolysis process for CO 2 conversion can be developed based on the already existing technologies such as water electrolyzers, polymer electrolyte membrane fuel cells, solid oxide fuel cells and so on [9].…”