Key Takeaways & Executive Findings
- •• Bimetallic catalysts enhance CO2 reduction by tuning electronic structure and creating synergistic active sites, overcoming limitations of single-metal catalysts. • The review covers both atomically dispersed bimetals on carbon supports and non-atomic bimetals like alloys and heterostructures, detailing synthesis and characterization methods. • Catalytic mechanisms for different bimetallic systems are proposed, highlighting how secondary metals optimize intermediate binding and reaction pathways. • Challenges in CO2RR, such as competing hydrogen evolution and product selectivity, are addressed through rational design of bimetallic catalysts.
Abstract
The electrocatalytic CO2 reduction reaction (CO2RR) is an environmentally friendly way to convert CO2 into valuable chemicals. However, CO2 conversion is a complex process, which contains 2, 4, 6, 8, and 12 electron transfer processes. It is very important to develop efficient catalysts to precisely control the number of electron transfers for the chemicals required. Single-metal catalysts have some deficiencies, including slow reaction kinetics, low product selectivity and inadequate stability. In response to these challenges, bimetallic catalysts have received significant attention owing to their unique structure and improved performance. The introduction of secondary metals alters the catalyst’s electronic structure, and creates novel active sites, as well as optimizing their interaction with the intermediates. This review provides a comprehensive account of atomically distributed bimetals based on carbon materials and non-atomic distributed bimetals such as alloys and heterostructures, including their synthesis methods, characterization, and the outcomes of different catalysts. Catalytic mechanisms of different bimetallic catalysts are proposed and challenges encountered in the CO2RR are considered.
1. Introduction
Carbon dioxide emissions resulting from the overconsumption of fossil fuels have led to serious climate hazards, the overarching effects of which are often irreversible within 1 000 years[1,2]. As a result, it is imperative to either reduce CO2 emissions or convert it to valuable chemicals. The electroreduction of CO2 is an effective and clean strategy for CO2 reduction[3–5]. CO2 reduction involves a variety of reaction paths (Table 1). Commonly there are 2, 4, 6, 8 and 12 electron transfer processes[6–8]. The resulting products, such as CO and syngas (CO+H2), can be used to produce hydrocarbons or oxygenates by the Fischer-Tropsch synthesis method[9,10], and other chemicals such as methanol, formaldehyde, methane, ethanol, and several others can also be obtained from CO2 reduction. The products of CO2 reduction are sensitive to the practical applications and tends to produce a variety of products, which is one of the significant challenges in this area. On the other hand, considerable thermodynamic and kinetic barriers caused by the stable C＝O bond exist in the process of CO2 reduction[11–13]. Additionally, a competing hydrogen evolution reaction (HER) is also unavoidable[14–16]. Therefore, it is of great significance to develop efficient catalysts to improve CO2 reduction reaction (CO2RR)[17,18].
Single-atom catalysts (SACs) have attracted significant attention in the field of CO2RR due to their good catalytic performance. The unsaturated coordination configuration of atoms in SACs makes them more active in many reactions. In addition, SACs allow for the design of active sites with well-defined positions through the tunable coordination environment, resulting in excellent activity and selectivity for specific reactions[19–21]. For instance, Yang et al.[22] designed a catalyst containing high dispersions of Fe-N4 moieties with a hierarchical structure, which prevented the migration and aggregation of Fe3+ due to the strong binding between metal ions and nitrogen. The porous structure of the catalyst also facilitated fast ion transfer and allowed for sufficient exposure of active sites, ultimately improving the selectivity of the catalyst. The Faraday efficiency of CO (FECO) achieved by this catalyst was up to 89%. However, SAC has only one act...
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LIAO Yin-li, HUANG Heng-bo, ZOU Ru-yu, SHEN Shu-ling, LIU Xin-juan, TANG Zhi-hong (2025). A review of the synthesis, characterization, and mechanism of bimetallic catalysts for electrocatalytic CO2 reduction. SinoTechIntel Verified Research. https://doi.org/10.1016/S1872-5805(NCM2024-39-03-01)
Research & Educational Purpose Only:The translations, structured abstracts, analytical annotations, and data reports provided by SinoTechIntel are intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
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Frequently Asked Questions
What are the main advantages of bimetallic catalysts over single-metal catalysts for CO2 reduction?
Bimetallic catalysts offer improved reaction kinetics, higher product selectivity, and better stability compared to single-metal catalysts. The introduction of a secondary metal modifies the electronic structure, creates novel active sites, and optimizes interactions with reaction intermediates, leading to enhanced catalytic performance.
What types of bimetallic catalysts are discussed in this review?
The review covers two main categories: atomically distributed bimetals supported on carbon materials, and non-atomic distributed bimetals such as alloys and heterostructures. It details their synthesis methods, characterization, and catalytic outcomes.
How do bimetallic catalysts improve the selectivity of CO2 reduction products?
By tuning the electronic structure and geometry of active sites, bimetallic catalysts can stabilize specific reaction intermediates, thereby directing the reaction pathway toward desired products like CO, formate, or hydrocarbons, while suppressing the competing hydrogen evolution reaction.
What are the key challenges in CO2 electroreduction that bimetallic catalysts address?
Key challenges include the high thermodynamic stability of CO2, slow kinetics, and competing hydrogen evolution. Bimetallic catalysts help lower activation barriers, enhance reaction rates, and improve selectivity, thus mitigating these issues.
What is the significance of the synergistic effect in bimetallic catalysts?
The synergistic effect arises from the interaction between two different metals, which can alter electronic properties, create bifunctional active sites, and promote cooperative adsorption of intermediates. This leads to enhanced activity, selectivity, and stability compared to monometallic counterparts.
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