Ag-Sn interfacial electronic structure modulation for high-efficiency CO2 electroreduction at 1 A/cm2 under acidic conditions

doi:10.11949/0438-1157.20250288

Abstract

Abstract:

Electrocatalytic CO₂ reduction under acidic conditions has attracted significant attention due to its ability to enhance CO₂ utilization and suppress carbonate formation. However, the elevated H⁺ concentration in acidic environments intensifies the competing hydrogen evolution reaction (HER), thereby imposing higher requirements on catalyst stability and selectivity. Herein, we report an Ag-Sn bimetallic catalyst that exhibits outstanding CO₂RR performance in an acidic membrane electrode assembly (MEA) at pH=2. Under a current density of 400 mA/cm², the catalyst achieves a CO selectivity of up to 99.4%, and even at 1 A/cm², the CO Faraday efficiency (FE_CO) remains at 83.5%, with a maximum CO partial current density reaching 834.8 mA/cm². The study found that the introduction of a small amount of Sn can adjust the electronic structure of Ag, thereby accelerating the activation of CO₂ and the transformation to *COOH intermediates. This work provides a new strategy for developing highly efficient and stable CO₂RR catalysts suitable for operation under acidic conditions.

Key words: acid, electrocatalytic carbon dioxide reduction, MEA, Faraday efficiency, CO partial current density, electronic structure, activation, intermediate

摘要：

酸性条件下的电催化二氧化碳还原（CO₂RR）因其能够提高CO₂利用率并抑制碳酸盐形成而备受关注。然而，酸性环境由于H⁺浓度升高导致竞争性析氢反应（HER）加剧，从而对催化剂的稳定性和选择性提出了更高的要求。在此，报道了一种Ag-Sn双金属催化剂，在pH=2的酸性膜电极中表现出了优异的CO₂RR性能。该催化剂在400 mA/cm²的电流密度下CO选择性高达99.4%，且在1 A/cm²的条件下，CO的法拉第效率（FE_CO）仍能维持在83.5%，CO的分电流密度最高达到了834.8 mA/cm²。研究发现，少量Sn的引入能够调节Ag的电子结构，从而加速CO₂活化以及向*COOH中间体的转变。这项工作为开发适用于酸性条件的高效稳定CO₂RR催化剂提供了新的思路。

关键词: 酸性, 电催化CO₂还原, MEA, 法拉第效率, CO分电流密度, 电子结构, 活化, 中间体

CLC Number:

TQ 151.1

Zhizhong PENG, Xuelei LANG, Qiang FANG, Huifang JING, dazhong ZHONG, Jinping LI, Qiang ZHAO. Ag-Sn interfacial electronic structure modulation for high-efficiency CO₂ electroreduction at 1 A/cm² under acidic conditions[J]. CIESC Journal, 2025, 76(12): 6376-6386.

彭郅众, 郎学磊, 房强, 井慧芳, 钟达忠, 李晋平, 赵强. Ag-Sn间电子结构调控在酸性环境中实现1 A/cm²下高效CO₂还原[J]. 化工学报, 2025, 76(12): 6376-6386.

Figures/Tables 15

Fig.1 Schematic of MEA cell

Fig.2 The scheme for the preparation of Ag-Sn1.4%

Fig.3 (a) XRD of Ag-Sn and Ag NP; XPS for (b) Ag-Sn4.9%; (c) Ag-Sn1.4%; (d) Ag-Sn0.2%

Fig.4 SEM of (a) Ag NP, (b) Ag-Sn0.2%, (c) Ag-Sn1.4%, (d) Ag-Sn4.9%

Fig.5 (a) TEM of Ag-Sn1.4%; (b) HRTEM of Ag-Sn1.4%; (c) TEM of Ag NP; (d) HRTEM of Ag NP

Fig.6 Mapping of Ag-Sn1.4%

Fig.7 ECSA

Fig.8 Cdl of Ag-Sn1.4% and Ag NP

Fig.9 (a) Effect of pH of reaction solution during synthesis and loading of Ag-Sn catalyst on catalytic performance; (b) Pre-reduction process of Ag-Sn at 50 mA/cm2

Fig.10 FE and potential

Fig.11 (a) Comparison of samples with different Sn contents at 400 mA/cm2 and 1 A/cm2; (b) CO partial current density

Table 1 Comparison of catalytic activity in MEA

Catalyst	J_Total/(mA/cm²)	Electrolyte	FE_CO/%	Ref.
Ag-Sn_1.4%	1000	K₂SO₄+ H₂SO₄	83.5	this work
Ag-Sn_1.4%	400	K₂SO₄+ H₂SO₄	99.4	this work
Ni-N-C	500	K₂SO₄+ H₂SO₄	约80	[30]
Ag	60	Cs₂SO₄+ H₂SO₄	约80	[31]
Ag@C-d	200	K₂SO₄+ H₂SO₄	91.6	[32]
Ag∶Cs-DC	400	KHCO₃	81.6	[33]
Ni₁-NSC	225	KOH	约100	[34]

Fig.12 (a) Energy efficiency of Ag-Sn1.4% and Ag NP; (b) SPCE of Ag-Sn1.4%; (c) Stability test of Ag-Sn1.4% at pH=2

Fig.13 In situ Raman spectroscopy of Ag-Sn1.4%(a) and Ag NP(b)

Fig.14 Ag 3d XPS spectra of Ag-Sn1.4% and Ag NP

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Ag-Sn interfacial electronic structure modulation for high-efficiency CO₂ electroreduction at 1 A/cm² under acidic conditions

Ag-Sn间电子结构调控在酸性环境中实现1 A/cm²下高效CO₂还原

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