Key Takeaways & Executive Findings
- •• • The Cu-Sn alloy catalyst achieves a maximum Faradaic efficiency of 80% for formate production, outperforming pure Cu and Sn electrodes, which is critical for industrial viability where high selectivity directly reduces downstream separation costs. • • The catalyst maintains >70% Faradaic efficiency across a wide potential window (-1.7 V to -2.0 V vs. Ag/AgCl), offering operational flexibility and robustness against potential fluctuations in renewable energy-powered electrolyzers. • • The one-step electrodeposition method is simple, green, and scalable, potentially lowering manufacturing costs compared to multi-step or high-temperature synthesis routes, thus addressing economic barriers to commercial CO2RR deployment. • • The wheat-ear-like dendritic structure provides abundant active sites, enhancing CO2 adsorption and reaction kinetics, as evidenced by higher current densities and stability in chronoamperometric tests, which is essential for achieving industrially relevant production rates.
Abstract
Electrocatalytic CO2 reduction reaction (CO2RR) offers a promising route to mitigate CO2 emissions while producing valuable chemicals. This study reports a Cu-Sn alloy catalyst with a wheat-ear-like dendritic structure, fabricated via a one-step electrodeposition method, for selective CO2 electroreduction to formate. Compared to pure Cu and Sn electrodes, the Cu-Sn alloy exhibits superior catalytic activity and selectivity toward formate, achieving a maximum Faradaic efficiency (FE) of 80% and maintaining above 70% FE over a potential window from -1.7 V to -2.0 V (vs. Ag/AgCl). The enhanced performance is attributed to the unique dendritic morphology that provides abundant active sites and the synergistic alloying effect that modulates the adsorption of the CO2*- intermediate, as corroborated by electrochemical measurements and X-ray photoelectron spectroscopy (XPS). This work presents a facile strategy for designing bimetallic catalysts for efficient CO2RR to formate.
1. Introduction
The escalating atmospheric CO2 concentration, exceeding ten billion tonnes annually, has intensified the urgency for effective carbon mitigation strategies. While carbon capture and storage (CCS) can directly sequester CO2, its high cost and long-term storage liabilities hinder widespread adoption. Electrocatalytic CO2 reduction (CO2RR) emerges as a compelling alternative, converting CO2 into high-value chemicals using renewable electricity under mild conditions. Among potential products, formate (HCOO-) is particularly attractive due to its high economic value and use in fuel cells and hydrogen storage. However, conventional single-metal catalysts suffer from trade-offs: In-based catalysts achieve high formate selectivity (FE up to 85%) but suffer from low current densities (2-5 mA/cm2); Sn-based catalysts require high overpotentials (-1.8 V vs. Ag/AgCl) and exhibit low mass activity (<8 mA/mg); Cu, while active for CO2RR, produces a wide range of products with poor formate selectivity and significant hydrogen evolution. These limitations underscore the need for catalyst designs that simultaneously enhance activity, selectivity, and stability.
Alloying presents a promising strategy to overcome these bottlenecks by creating electronic interfaces that modulate intermediate binding energies. This study addresses the challenge by developing a Cu-Sn alloy catalyst via a simple one-step electrodeposition method. The alloy combines Cu's high catalytic activity with Sn's selectivity for formate, while the resulting wheat-ear-like dendritic structure provides a large electrochemically active surface area. This synergistic approach not only achieves a high Faradaic efficiency of 80% for formate but also maintains >70% efficiency over a wide potential range, offering a practical pathway for efficient and selective CO2-to-formate conversion.
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MIAO Jiahe, YANG Song, HU Hao, BAI Yadong, YANG Yanyan, YU Zhongliang (2026). One-Step Electrodeposition of Cu-Sn Alloy Catalysts for Efficient Electroreduction of CO2 to Formate. Journal of Fuel Chemistry and Technology. https://doi.org/10.3724/2097-213X.2025.JFCT.0027
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Frequently Asked Questions
What is the maximum Faradaic efficiency for formate and over what potential range does the catalyst maintain high efficiency?
The Cu-Sn alloy catalyst achieves a maximum Faradaic efficiency of 80% for formate. It maintains above 70% Faradaic efficiency within the potential window from -1.7 V to -2.0 V (vs. Ag/AgCl), indicating robust performance across a range of applied potentials.
How does the Cu-Sn alloy catalyst compare to pure Cu and Sn electrodes in terms of catalytic activity and selectivity?
The Cu-Sn alloy exhibits higher catalytic activity and selectivity toward formate compared to pure Cu and Sn electrodes. This is attributed to its unique wheat-ear-like dendritic structure, which provides abundant active sites, and the synergistic alloying effect that modulates the adsorption of CO2*- intermediate, as confirmed by electrochemical data and XPS analysis.
What is the significance of the one-step electrodeposition method for industrial scalability?
The one-step electrodeposition method is simple, green, and cost-effective, making it highly suitable for large-scale production. Unlike complex multi-step or high-temperature synthesis routes, this method can be easily scaled up, potentially reducing manufacturing costs and facilitating commercial deployment of CO2RR technology.
What is the role of the wheat-ear-like dendritic structure in enhancing CO2RR performance?
The wheat-ear-like dendritic structure provides a large electrochemically active surface area, which enhances CO2 adsorption and facilitates the reaction. This morphology increases the number of active sites, leading to higher current densities and improved stability during chronoamperometric tests, as observed in the study.
What mechanistic insights were revealed by XPS analysis regarding the alloy's effect on CO2RR?
XPS analysis revealed that Cu and Sn atoms collectively modulate the adsorption of the CO2*- intermediate. The alloying effect alters the electronic structure, optimizing the binding strength of CO2*- and promoting its subsequent protonation to form *OCHO, a key intermediate for formate production. This enhances the selectivity toward formate over other products.
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