Insight on Atomically Dispersed Cu Catalysts for Electrochemical CO₂ Reduction

Abstract

Electrochemical CO2 reduction (ECO2R) with renewable electricity is an advanced carbon conversion technology. At present, copper is the only metal to selectively convert CO2 into multicarbon (C2+) products. Among them, atomically dispersed (AD) Cu catalysts have received great attention due to the relatively single chemical environment, which are able to minimize the negative impact of morphology, valence state, and crystallographic properties, etc. on product selectivity. Furthermore, the completely exposed atomic Cu sites not only provide space and bonding electrons for the adsorption of reactants in favor of better catalytic activity but also provide an ideal platform for studying its reaction mechanism. This review summarizes the recent progress of AD Cu catalysts as a chemically tunable platform for ECO2R, including the atomic Cu sites dynamic evolution, the catalytic performance, and mechanism. Furthermore, the prospects and challenges of AD Cu catalysts for ECO2R are carefully discussed. We sincerely hope that this review can contribute to the rational design of AD Cu catalysts with enhanced performance for ECO2R.

A molecular view of single-atom catalysis toward carbon dioxide conversion

“…These cases all suggest that two adjacent and similar active sites might favor the production of C 2+ chemicals, and copper might be the best choice because of the moderate adsorption of intermediate species. 288,289 Recently, however, a tin-based tandem catalyst featuring Sn single atoms and SnS 2 nanosheets was developed for electroreduction of CO 2 to ethanol with a selectivity of 82.5%. A mechanistic pathway promoting C–C bond formation via a formyl-bicarbonate coupling intermediate was proposed by identifying the dual active centers of Sn and O atoms that could adsorb *CHO and *CO(OH) intermediates, respectively.…”

Electronic Structure Design of Transition Metal-Based Catalysts for Electrochemical Carbon Dioxide Reduction

“…The strategic incorporation of transition metal atoms into carbon-based substrates constitutes a pivotal approach in nanomaterial design. ,− Leveraging the excellent conductivity and stability of carbon substrates, this method establishes a robust platform, allowing for intricate fine-tuning through the modulation of metal type and concentration. , It is worth noting that incorporating transition metal atoms as active sites with the inactive carbon substrate markedly improves the atomic utilization rate compared with bulk materials. , Moreover, carbon substrate can provide further adjustment space of active sites, such as secondary atom doping. , Built upon carbon substrates, single-atom catalysts (SACs), featuring individual metal atoms affixed to the support surface, have attracted tremendous research interests owing to their intriguing catalytic performance compared to conventional nanoparticle catalysts, including high atom efficiency, high utilization of metal valence electrons, excellent thermal stability, and flexible tunability. ,− It is worth mentioning that since their inception, SACs have not only been limited to a single atom anchored to a substrate, but evolving to a more intricate structure with multiple nonmetallic atoms cooperating (e.g., M–N–C catalysts, M = metal atom) − or multiple transition metal atoms (e.g., dual atom catalysts (DACs). − CO 2 RR over SACs traces its origins to 1970s, where cobalt and nickel phthalocyanines (Pc) were used for this process . It had declared that compared with Mn-Pc and Fe-Pc, the d z orbitals of Co-Pc and Ni-Pc in their dinegative states were occupied and ligand π electrons were excessive, where a foundation was laid for the later further tuning and optimization of the electronic structure of monatomic transition metals .…”

Built-in Electric Field Promotes Interfacial Adsorption and Activation of CO2 for C1 Products over a Wide Potential Window

“…Transforming CO 2 into high-value chemicals through electrocatalytic CO 2 reduction reaction (CO 2 RR) using renewable electricity is promising. − Among the possible reduction products, C 1 products (CO and HCOO – ) are appealing due to their low electron consumption and the highest added value per kWh of electrical energy input. − However, as a gas-consuming reaction, the chemisorption and activation of CO 2 are essential prerequisites. − At the same time, the sluggish electron transfer due to the complex proton-coupled electron processes limits the catalytic kinetics. − As known, the potential window for high catalytic activity and selectivity of commonly studied alloy catalysts toward C 1 products is narrow (<0.3 V). , …”