Lithium Vacancy‐Tuned [CuO₄] Sites for Selective CO₂ Electroreduction to C₂₊ Products

Abstract

Electrochemical CO2 reduction to valuable multi‐carbon (C2+) products is attractive but with poor selectivity and activity due to the low‐efficient CC coupling. Herein, a lithium vacancy‐tuned Li2CuO2 with square‐planar [CuO4] layers is developed via an electrochemical delithiation strategy. Density functional theory calculations reveal that the lithium vacancies (VLi) lead to a shorter distance between adjacent [CuO4] layers and reduce the coordination number of Li+ around each Cu, featuring with a lower energy barrier for COCO coupling than pristine Li2CuO2 without VLi. With the VLi percentage of ≈1.6%, the Li2−xCuO2 catalyst exhibits a high Faradaic efficiency of 90.6 ± 7.6% for C2+ at −0.85 V versus reversible hydrogen electrode without iR correction, and an outstanding partial current density of −706 ± 32 mA cm−2. This work suggests an attractive approach to create controllable alkali metal vacancy‐tuned Cu catalytic sites toward C2+ products in electrochemical CO2 reduction.

Surface Co‐Modification of Halide Anions and Potassium Cations Promotes High‐Rate CO2‐to‐Ethanol Electrosynthesis

“…At j total of −1000 mA cm −2 (with the applied potential of −0.68 V), the partial current density |j C2H5OH | was further increased to 439 ± 22 mA cm −2 on the K-F-Cu-CO 2 catalyst, which was 3.05-fold of F-Cu-CO 2 (144 ± 14 mA cm −2 ), 2.99-fold of K-F-Cu-Ar (147 ± 9 mA cm −2 ), and 2.24-fold of KF@Cu-CO 2 (196 ± 22 mA cm −2 ). Our results featured one of the highest |j C2H5OH |, excellent FE C2H5OH and EE C2H5OH values, compared with the reported literature to date [8][9][10][11]13,[17][18][19][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44] (Figure 3f, Figure S12 and Table S9, Supporting Information).…”

“…The *CO-CO coupling, generally regarded as the rate determining step for C 2+ products, [13,14,17,18] was then calculated. The energy barrier and reaction energy for the *CO-CO coupling on the K-F-Cu model were calculated 0.644 and 0.539 eV, respectively, both of which were lower than those calculated on Cu (0.731 and 0.624 eV, Figure 4a intermediate, [10,20] which were bifurcated via either hydrogenating CC bond (i.e., the C 2 H 5 OH pathway) or breaking CO bond (i.e., the C 2 H 4 pathway).…”

“…[8,9,[12][13][14] The unfavored ethanol selectivity in CO 2 RR is attributed to its relatively less stable oxygenate intermediates (e.g., CH 3 CHO*) [15,16] than C 2 H 4 under low and mid overpotential ranges, as well as the dominating production of CH 4 and H 2 (hydrogen evolution from water reduction) at high overpotentials. [17,18] To date, most of the reported CO 2 -to-ethanol partial current densities are still below 200 mA cm −2 , [9][10][11]19,20] thus precluding the large-scale deployment of this technology.…”

Plasmonic Ag-decorated Cu2O nanowires for boosting photoelectrochemical CO2 reduction to multi-carbon products

“…The construction of active sites is thus important to improve the catalytic activity, especially in the formation of C 2 products. 11 The main challenge in the formation of C 2 products is the C–C coupling of one-carbon intermediates. In fact, the active sites and binding strength of intermediates are mainly determined by the d-band electronic structure of the catalyst surface itself.…”

Highly‐Exposed Single‐Interlayered Cu Edges Enable High‐Rate CO2‐to‐CH4 Electrosynthesis

“…The peak j CH 4 of 717 ± 33 mA cm −2 on the CuGaO 2 nanosheet catalyst represents the highest reported electrochemical CO 2 -to-CH 4 value to date (Figure 4e; Table S6, Supporting Information). [9][10][11][12][13]15,[29][30][31][32][33][34][35][36][37][38] S6, Supporting Information). f) Applied potentials (grey curve, left y-axis) and FE CH 4 (blue squares, right y-axis) versus time using the CuGaO 2 nanosheet catalyst at a constant total current density of -1 A cm −2 .…”