Over 70 % Faradaic Efficiency for CO₂ Electroreduction to Ethanol Enabled by Potassium Dopant‐Tuned Interaction between Copper Sites and Intermediates

Abstract

It is highly desired yet challenging to steer the CO 2 electroreduction reaction (CO 2 ER) toward ethanol with high selectivity, for which the evolution of reaction intermediates on catalytically active sites holds the key. Herein, we report that K doping in Cu 2 Se nanosheets array on Cu foam serves as a versatile way to tune the interaction between Cu sites and reaction intermediates in CO 2 ER, enabling highly selective production of ethanol. As revealed by characterization and simulation, the electron transfer from K to Se can stabilize Cu I species which facilitate the adsorption of linear *CO L and bridge *CO B intermediates to promote CÀ C coupling during CO 2 ER. As a result, the optimized K 11.2% -Cu 2 Se nanosheets array can catalyze CO 2 ER to ethanol as a single liquid product with high selectivity in a potential area from À 0.6 to À 1.2 V. Notably, it offers a Faradaic efficiency of 70.3 % for ethanol production at À 0.8 V with as is stable for 130 h.

Efficient Electrocatalytic Reduction of CO2 to Ethanol Enhanced by Spacing Effect of CuCu in Cu2‐xSe Nanosheets

“…Besides, the peak intensity of *CHO is increased as the applied potentials from 0 to −1.6 V, indicating that the progress of producing *CHO is propitious and the depletion step of *CHO may be a decisive step of the reaction rate. This asymmetric C−C coupling has a lower energy barrier than that for *CO dimerization as evidenced by the reported theory studies, [ 13 ] which contributes to increased C2+ production. Surprisingly, new bands show up at 1550 and 1340 cm −1 , which are assigned as CO stretching vibration of *COCHO and CH bending vibration of *C 2 H 5 OH, respectively.…”

“…Several strategies have been adopted to address the problem. First, building a tandem catalyst can improve the local CO concentration and change the binding strength of *CO, form a mixed adsorption configuration and trigger an asymmetric CC coupling, thus stabilizing the oxygenous intermediates; [12] Second, cation doping can regulate the interaction between the Cu site and the reaction intermediate in the CO 2 ER, increase the binding strength of *CO B and *CO L on the catalyst surface, and promote the subsequent CC coupling to generate EtOH; [13]…”

Exploring Ligand-Controlled C2 Product Selectivity in Carbon Dioxide Reduction with Copper Metal–Organic Framework Nanosheets

“…However, metallic Cu(0), with its low activation energy and moderate binding energy toward most carbon-containing reaction intermediates, allows to form a wide variety of reduction products and produces poor selectivity. ,, Catalysts (CuO x , CuSe 1– x , etc.) with mixed valent Cu 0 , Cu + , and Cu 2+ species have been explored to attain high selectivity for C 2 products. , Although Cu + offers selectivity toward C 2 products, it undergoes electroreduction at a high negative potential to form Cu 0 species and hence affects the selectivity of C 2 products. , Therefore, the cooperative electronic interaction between Cu 0 , Cu + , and Cu 2+ species is important to stabilize the Cu + species at high cathodic potential and to attain improved C 2 product selectivity. − …”

“…23,24 Although Cu + offers selectivity toward C 2 products, it undergoes electroreduction at a high negative potential to form Cu 0 species and hence affects the selectivity of C 2 products. 12,23 Therefore, the cooperative electronic interaction between Cu 0 , Cu + , and Cu 2+ species is important to stabilize the Cu + species at high cathodic potential and to attain improved C 2 product selectivity. 25−27 In this respect, Cu-based metal−organic frameworks (MOFs) with mixed valent copper ions have been explored to achieve promising activity for electrocatalytic CO 2 RR and selectivity toward C 2 products.…”

Efficient Liquid Multicarbon Production from Overall CO2 Photoreduction by Creating a Superhydrophobic Gas Storage Space

“…4 Cu 2 O is one of the most promising materials for liquid multicarbon production from photocatalytic CRR, whose low-coordinated Cu + surface atoms could facilitate the adsorption of *CO, which is a key intermediate for C-C coupling during CRR. 10,11 Based on Cu 2 O material, numerous methods aiming to elevate the generation of multicarbon products such as heterojunction construction, 12 cocatalyst engineering, 13 etc. have been adopted, which have been proven…”