Asymmetric Oxo-Bridged ZnPb Bimetallic Electrocatalysis Boosting CO2 -to-HCOOH Reduction

Aya Gomaa Abdelkader Mohamed; Enbo Zhou; Zipeng Zeng; Jiafang Xie; Dunfeng Gao; Yaobing Wang

doi:10.1002/advs.202104138

Asymmetric Oxo-Bridged ZnPb Bimetallic Electrocatalysis Boosting CO₂ -to-HCOOH Reduction

Adv Sci (Weinh). 2022 Feb;9(4):e2104138. doi: 10.1002/advs.202104138. Epub 2021 Nov 10.

Authors

Aya Gomaa Abdelkader Mohamed^{1

2}, Enbo Zhou^{1

2}, Zipeng Zeng^{1

2}, Jiafang Xie³, Dunfeng Gao⁴, Yaobing Wang^{1

4

5}

Affiliations

¹ CAS Key Laboratory of Design and Assembly of Functional Nanostructures, and Fujian Provincial Key Laboratory of Nanomaterials, State Key Laboratory of Structural Chemistry, Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian, 350002, China.
² University of Chinese Academy of Sciences, Beijing, 100049, China.
³ Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen, 361021, China.
⁴ Dalian National Laboratory for Clean Energy, Dalian, 116023, China.
⁵ Fujian Science and Technology Innovation Laboratory for Optoelectronic Information of China, Fuzhou, 350108, China.

Abstract

Electrochemical CO₂ reduction (ECR) is one of the promising CO₂ recycling technologies sustaining the natural carbon cycle and offering more sustainable higher-energy chemicals. Zn- and Pb-based catalysts have improved formate selectivity, but they suffer from relatively low current activities considering the competitive CO selectivity on Zn. Here, lead-doped zinc (Zn(Pb)) electrocatalyst is optimized to efficiently reduce CO₂ to formate, while CO evolution selectivity is largely controlled. Selective formate is detected with Faradaic efficiency (FE_HCOOH ) of ≈95% at an outstanding partial current density of 47 mA cm^-2 in a conventional H-Cell. Zn(Pb) is further investigated in an electrolyte-fed device achieving a superior conversion rate of ≈100 mA cm^-2 representing a step closer to practical electrocatalysis. The in situ analysis demonstrates that the Pb incorporation plays a crucial role in CO suppression stem from the generation of the Pb-O-C-O-Zn structure rather than the CO-boosted Pb-O-C-Zn. Density functional theory (DFT) calculations reveal that the alloying effect tunes the adsorption energetics and consequently modifies the electronic structure of the system for an optimized asymmetric oxo-bridged intermediate. The alloying effect between Zn and Pb controls CO selectivity and achieves a superior activity for a selective CO₂ -to-formate reduction.

Keywords: CO2 reduction; bimetallic electrocatalyst; electrocatalysis; formate; selectivity.

Abstract

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