Synergistic Cr₂O₃@Ag Heterostructure Enhanced Electrocatalytic CO₂ Reduction to CO

Abstract

Although various chemicals and fuels have been successfully synthesized via the electrocatalytic CO 2 reduction reaction (CO 2 RR), the selective reduction of CO 2 to CO is widely recognized as one of the most economically viable reactions due to its simplicity and needing the least electrons transfer to form the product. [2] Among the reported CO 2 RR electrocatalysts, metallic Ag ones have demonstrated high catalytic selectivity toward CO, however, requiring high cathodic potentials (e.g., ≥0.9 V vs RHE). [3] Various approaches have been attempted to improve the CO 2 RR performance of Ag electrocatalysts. For instance, Kim and co-workers immobilized small Ag NPs (≈5 nm) on carbon support to achieve a high faradic efficiency (FE CO ) of 84.4% at −0.75 V versus RHE. [4] Luo and co-workers reported the use of the dominant Ag (100) facet exposed at the active edge of the triangular Ag nanoplates to attain a high FE CO of 96.8% at −0.855 V versus RHE. [5] Recently, the same team investigated the structure sensitivity of Ag nanocubes toward CO 2 RR and unveiled that the Ag nanocubes enclosed by {100} facets with the edge lengths below 25 nm can achieve a superb FE CO of 99.0% at −0.856 V versus RHE. [6] They attributed the superb FE CO to the increased percentage of edge active sites. These approaches utilize the edge active sites of Ag nanocrystals to improve CO 2 RR performance, however, such highly active edge sites areThe electrocatalytic CO 2 RR to produce value-added chemicals and fuels has been recognized as a promising means to reduce the reliance on fossil resources; it is, however, hindered due to the lack of high-performance electrocatalysts. The effectiveness of sculpturing metal/metal oxides (MMO) heterostructures to enhance electrocatalytic performance toward CO 2 RR has been well documented, nonetheless, the precise synergistic mechanism of MMO remains elusive. Herein, an in operando electrochemically synthesized Cr 2 O 3 -Ag heterostructure electrocatalyst (Cr 2 O 3 @Ag) is reported for efficient electrocatalytic reduction of CO 2 to CO. The obtained Cr 2 O 3 @Ag can readily achieve a superb FE CO of 99.6% at −0.8 V (vs RHE) with a high J CO of 19.0 mA cm −2 . These studies also confirm that the operando synthesized Cr 2 O 3 @Ag possesses high operational stability. Notably, operando Raman spectroscopy studies reveal that the markedly enhanced performance is attributable to the synergistic Cr 2 O 3 -Ag heterostructure induced stabilization of CO 2 •−/*COOH intermediates. DFT calculations unveil that the metallic-Ag-catalyzed CO 2 reduction to CO requires a 1.45 eV energy input to proceed, which is 0.93 eV higher than that of the MMO-structured Cr 2 O 3 @Ag. The exemplified approaches in this work would be adoptable for design and development of high-performance electrocatalysts for other important reactions.

Ag Nanoparticles/NiSx/ZnO Nanorods/Carbon Fiber Electrocatalysts for 5-Hydroxymethyl Furfural Oxidation and p-Nitrophenol Reduction: Implications for Green Chemical Electrosynthesis Applications

“…The characteristic peaks of Ag at 2θ = 38.2, 44.4, 64.5, 77.5, and 81.6° indicate (111), (200), (220), (311), and (222) crystalline phases (Figure b, yellow line), indicating that there is almost no metal to oxide conversion during the treatment (JCDPS No. 04–0783). ,− Typical peaks of NiS x at 2θ = 22.9, 31.5, 38.1, 44.7, 50.2, and 55.5° indicate (101), (110), (003), (202), (211), and (300) crystalline phases (Figure b, blue line), indicating the success of NiS x (JCDPS No. 44–1418) modification during the treatment .…”

Doping and pretreatment optimized the adsorption of *OCHO on bismuth for the electrocatalytic reduction of CO2to formate

“…S32,† the Ag/Bi 2 S 3 -10.24% XPS spectrum and Ag 3d XPS spectrum indicate that Ag + is the dominant valence state of silver, and Bi 3+ appears in the Bi 4f XPS spectrum in the form of Bi–O, which is consistent with the experimental results of Cu/Bi 2 S 3 . 43 The XRD patterns of Ag/Bi 2 S 3 -1.14%, Ag/Bi 2 S 3 -4.28%, and Ag/Bi 2 S 3 -10.24% after N 2 pretreatment proved the formation of bismuth (Fig. S33†).…”

Design and Synthesis of Ag‐based Catalysts for Electrochemical CO2 Reduction: Advances and Perspectives

“…For example, the presynthesized Ag 2 CrO 4 microcrystals (Ag 2 CrO 4 -MCs) can be converted to the Cr 2 O 3 @Ag heterostructure by a direct electrochemical approach under operando CO 2 RR conditions (Figure 5). [72] The Cr 2 O 3 @Ag heterostructure provides an elongated hexagon shape, which could convert CO 2 into CO with a superb FE CO of 99.6% and a high CO partial current density of 19.0 mA cm À 2 at À 0.8 V vs. RHE. Both the operando Raman spectroscopy and DFT calculations were used to reveal the mechanistic insights of the enhanced CO 2 RR performance.…”