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• Dendritic In-doped Cu@Cu 2 O catalyst is prepared by co-electrodeposition method. • Doped-In content can tailor Cu+/Cu0 ratio, charge distribution, morphology and ECSA. • Cu+/Cu0 ratio plays a vital role on enhancing FE CO and partial current density at low In doping. • 3.7% In-Cu sample shows the highest FE CO of 87.6 ± 2.2 % and j CO of 9.7 ± 1.04 mA cm -2. Element doping is an effective strategy to enhance the selectivity of electrochemical carbon dioxide reduction. In this work, a dendritic core-shell In-doped Cu@Cu 2 O catalyst is prepared by co-electrodeposition method on carbon fiber paper for selective electroreduction of CO 2 to CO. Faradaic efficiency of producing CO over this dendritic In-doped Cu@Cu 2 O reaches 87.6 ± 2.2% with total current density of 11.1 ± 0.85 mA cm−2 at −0.8 V vs RHE, which outperforms most of the reported Cu-based electrocatalysts. The excellent performance is mainly derived from charge re-distribution and the enhanced intrinsic activity due to the formation of In-doped Cu 2 O layer. Meanwhile, the Cu+/Cu0 can be adjusted by tailoring the doped-In content. The relatively high ECSA and small charge transfer resistance are also conducive to improve the selectivity and activity. The oxyphilic In metal incorporated into the copper lattice can well stabilize the intermediate *COOH through enhancing interaction with O-ends of *COOH. This work provides a facile approach and a deep insight on design and synthesis of high efficiency hybrid electrocatalysts. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of CO2 (CO2ER) into the renewable and sustainable green fuels, such as low-carbon alcohols, is one of several workable strategies. CO2ER can be combined with renewable electricity to transform intermittent energy sources (such as wind, hydro, and solar) into a fuel that can be stored until it is ready to be used. The intrinsic characteristics of the employed catalyst have a significant and substantial effect on the effi- ciency of CO2ER and the ensuing economic viability. The paradigmatic multicarbon alcohol catalysts should increase the concentration of *CO in the reaction environment, stabilize the key intermediate products during the reaction, and facilitate the C--C coupling interaction. Since graphene has a large surface area and exceptional conductivity, it has been used as a support for active phases (nanoparticles or nanosheets). It is possible for graphene to enhance charge transport and accelerate CO2 conversion through its electronic and structural coupling effects. At the interface, a synergy can be produced that improves CO22ER by increasing *CO adsorption, intermediate binding, and stability. This article focuses on recent advancements in graphene-based catalysts that promote CO2ER to alcohols. Likewise, this paper also describes and discusses the key role graphene plays in catalyzing CO2ER into alcohols. Finally, we hope to provide future ideas for the design of graphene-based electrocatalysts. [ABSTRACT FROM AUTHOR]

The electrocatalytic carbon dioxide reduction reaction (CO2RR) is considered as a promising approach for simultaneous CO2 treatment and production of value-added chemicals. Bismuth has been demonstrated as a fascinating electrocatalyst for selective conversion of CO2 to HCOOH. In this study, we comprehensively investigated the effects of size, morphology, and carbon supports on the CO2RR performance of Bi catalysts to enhance their electrocatalytic CO2RR activity and HCOOH selectivity. Specifically, Bi nanospheres with varying sizes were synthesized by adjusting the amount of polyvinylpyrrolidone (PVP), achieving similar selectivity for HCOOH but increasing current density with decreasing size. Bi nanoplates and Bi nanoflowers were also prepared through the reduction of BiOCl precursors, with Bi nanoflowers demonstrating a superior morphology compared to other Bi nanocrystals while achieving a HCOOH faradaic efficiency (FEHCOOH) of 95% at −1.6 V vs. SCE and excellent durability over 12 hours. The predominance of *HCOO intermediates in the in situ ATR-SEIRA spectra indicates that during the CO2RR, Bi nanoflowers primarily followed the pathway leading to HCOOH production. Furthermore, incorporation of Ketjenblack into the synthesis process resulted in carbon-supported Bi catalysts, which exhibited approximately 20% enhancement in FEHCOOH within a wide potential range from −1.3 V to −1.8 V vs. SCE due to an improved separation effect and electron transfer capacity provided by carbon materials. [ABSTRACT FROM AUTHOR]

Summary: The production of CO via electrochemical CO2 reduction has been recognised as a promising technology that overcomes the environmental issues caused by global warming. It also facilitates the conversion of CO2 into energy sources. Earth‐abundant Zn is a well‐known alternative to noble metal catalysts such as Au and Ag for the electrochemical CO2 reduction to CO. In particular, Zn‐based materials in the form of nanowires are potentially applicable as electrocatalysts in the electrochemical CO2 reduction. However, the conventional methods for manufacturing the nanowire structure are difficult as they require harsh conditions such as high temperatures and excess energy. In this study, Zn‐based nanowire catalysts are prepared by the facile electrodeposition of Zn nanostructures on a substrate followed by their energy‐free solution‐phase reconstitution. Further, their electrochemical performance in the CO2 reduction is investigated in a CO2‐purged 0.5 M KHCO3 electrolyte. By optimising the deposition conditions, hexagonal Zn (h‐Zn) plates with dominant Zn(101) facets, the favoured crystal structure for CO2 reduction, are fabricated on carbon paper. Furthermore, it is found that, during the solution‐phase reconstruction over 16 hours, the h‐Zn plate transforms to a nanowire owing to the differences between the oxidation rates of different crystal facets and the formation of a hydroxide complex. The activity of the reconstructed Zn‐based nanowire catalyst is enhanced further by forming an oxide layer via thermal treatment in a H2 atmosphere. This treatment boosted the reaction kinetics, thereby enhancing the catalyst performance in the CO2 reduction. [ABSTRACT FROM AUTHOR]

The development of efficient carbon dioxide reduction reaction (CO2RR) catalysts is one of the practical solutions to the current environmental problems. Usually, metal-doped catalysts are used for the CO2RR, but the metal elements can easily aggregate, resulting in a reduction in the catalytic performance. In this study, NiFe-LDH was exfoliated to single layer by a solid-phase exfoliation strategy, wherein Ni and Fe were doped on the char material owing to the pyrolysis of the solid-phase exfoliation agent, and the NiFe-CN catalyst with a gauzy and porous structure was obtained. The catalyst possessed excellent catalytic performance; particularly, when the mass fraction of NiFe-LDH was 1 wt%, the prepared catalyst (NiFe-CN-1) showed a faradaic efficiency of 93.5% for the reduction of CO2 to CO at −0.8 V (vs. reversible hydrogen electrode (RHE)) with a CO current density of 10.4 mA cm−2, which was due to the sufficient exposure of active sites and efficient proton transfer channels of NiFe-CN. This strategy provides a new idea to easily mass produce CO2RR electrocatalysts in an environmentally benign way. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of CO 2 over wood-derived metal-free N-doped carbon electrocatalysts provides a new route for converting CO 2 into value-added fuels However, it is a challenge to efficiently design and screen high-performance electrocatalysts. In this paper, we combined the Marcus equation with the theory of thermal-kinetic correlation to successfully predict the optimal N-C doping ratio. Poplar wood -derived 3D N-doped graphitized carbon with optimal N doping content (pyridine-N 1.87 at%, pyrrole-N, 1.52 at%), high specific surface area (471.2 m2 g−1), and abundant nanopores were successfully obtained with the assistance of melamine (N source), which exhibited a high ECR activity of 86.78 % at a low applied potential of −0.71 V (vs. RHE) and long-term stability of at least 10 cycles. This extends the application of the Marcus equation and improves new ideas for the future design of high-performance electrocatalysts. [Display omitted] • "Thermodynamic-kinetic-N/C doping ratio" curve established. • The accuracy of the "thermodynamics-kinetics -N/C doping ratio" curve is verified. • PB-NC4 shows high industrial potential. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of CO2 is a promising pathway for converting CO2 into valuable fuels and chemicals. The local environment at the cathode of CO2 electrolyzers plays a key role in determining activity and selectivity, but currently some mechanisms are still under debate. In particular, alkali metal cations have been shown to enhance the selectivity of metal catalysts, but their role remains less explored for molecular catalysts especially in high-current electrolyzers. Here, we investigated the enhancement effects of cations (Na+, K+, Cs+) on Co phthalocyanine (CoPc) in a state-of-the-art reverse-biased bipolar membrane electrolyzer. When added to the anolyte, these cations increased the Faradaic efficiency for CO, except in the case of Na+ in which the effect was transient, but the effects are convoluted with the transport process through the membrane. Alternatively, these cations can also be added directly to the cathode as chloride salts, allowing the use of a pure H2O anolyte feed, leading to sustained improved CO selectivity (61% at 100 mA cm−2 after 24 h). Our results show that cation addition is a simple yet effective strategy for improving the product selectivity of molecular electrocatalysts, opening up new avenues for tuning their local environment for CO2 reduction. This article is part of the discussion meeting issue 'Green carbon for the chemical industry of the future'. [ABSTRACT FROM AUTHOR]

Heterogeneous molecular catalysts have attracted considerable attention as carbon dioxide reduction reaction (CO2RR) electrocatalysts. The π‐electron system of conjugated ligands in molecular catalysts may play an important role in determining the activity. In this work, by enlarging π‐conjugation through appending more aromatic substituents on the porphyrin ligand, altered π‐electron system endows the as‐prepared 5,10,15,20‐tetrakis(4‐(pyren‐1‐yl)phenyl)porphyrin CoII with high Faradaic efficiency (ca. 95 %) for CO production, as well as high turnover frequency (2.1 s−1 at −0.6 V vs. RHE). Density functional theory calculation further suggests that the improved electrocatalytic performance mainly originates from the higher proportion of Co dz2 orbital and the CO2 π* orbital in the HOMO of the (Co−porphyrin−CO2)− intermediate with larger π‐conjugation, which facilitates the CO2 activation. This work provides strong evidence that π‐conjugation perturbation is effective in boosting the CO2RR. [ABSTRACT FROM AUTHOR]

The design of highly stable, effective, and selective electrocatalysts is essential for electrochemical reduction of carbon dioxide (CO2). Here, on the basis of density functional theory (DFT) computations, the reaction mechanisms of the reduction of CO2 over a series of bis(iminothiolato)metal (TMIT, TM = Mn, Fe, Co, Ni, Cu, Ru, Rh, and Pd) were studied. It is found that the CO2RR activity of TMIT depends on the choice of the central metal atom. Our results demonstrated that HCOOH is the main product for TMIT (TM = Mn, Fe, Co, Ni, Cu, Pd). Among them, MnIT and FeIT are promising CO2RR catalysts for the HCOOH production due to the good selectivity and catalytic activity with the low overpotential of 0.34 V and 0.35 V, respectively. For RuIT and RhIT, the main product is CO, and the strong adsorption of CO on the catalyst surfaces would poison the catalysts. This makes RhIT and RuIT not good CO2RR catalysts. We anticipate that this work may shed new light on the development of high-performance metal organic framework (MOF)-based electrocatalysts. [ABSTRACT FROM AUTHOR]

The electrochemical carbon dioxide reduction reaction (CO2RR) is an attractive approach for mitigating CO2 emissions and generating value-added products. Consequently, discovery of promising CO2RR catalysts has become a crucial task, and machine learning (ML) has been utilized to accelerate catalyst discovery. However, current ML approaches are limited to exploring narrow chemical spaces and provide only fragmentary catalytic activity, even though CO2RR produces various chemicals. Here, by merging pre-developed ML model and a CO2RR selectivity map, we establish high-throughput virtual screening strategy to suggest active and selective catalysts for CO2RR without being limited to a database. Further, this strategy can provide guidance on stoichiometry and morphology of the catalyst to researchers. We predict the activity and selectivity of 465 metallic catalysts toward four expected reaction products. During this process, we discover previously unreported and promising behavior of Cu-Ga and Cu-Pd alloys. These findings are then validated through experimental methods. Conventional ab initio calculations and machine learning provide limited information on catalytic activity and selectivity and often show discrepancy with experimental results. Here, the authors report a high-throughput virtual screening strategy to identify active and selective catalysts, leading to the discovery of Cu-Ga and Cu-Pd catalysts for CO2 electroreduction. [ABSTRACT FROM AUTHOR]

Electrocatalytic CO2 reduction reaction (CRR) is a promising way to convert carbon dioxide (CO2) into value‐added hydrocarbons to alleviate the ever‐increasing environmental problem and accelerate the realization of carbon cycling. Cost‐effective and stable electrocatalytic materials with low overpotential, superior selectivity, excellent activity and great stability are critically important to achieve such a target. Cu‐based electrocatalysts are promising candidates for electrochemical CRR due to their versatile abilities of converting CO2 into various products. This review analyzes and summarizes the current progress in utilization of Cu‐based catalytic materials for electrochemical CRR. Monometallic, bimetallic, trimetallic, and multimetallic Cu‐based electrocatalysts with variable elemental compositions and tunable morphologies, including Cu nanowires, Cu nanocubes (NCs), Cu porous structures, Cu‐based alloys, Cu‐oxide/hydrogen oxide, Cu single atoms, and 2D substrate‐supported Cu electrocatalysts for CRR, are surveyed. Substantial advances in overcoming the existing bottlenecks of eletrocatalysts and effectively improving CRR performance of Cu‐based electrocatalysts for future applications are systematically discussed. Challenges and perspectives of Cu‐based electrocatalytic materials for CRR are also offered, which may shed light on further development of Cu‐based electrocatalysts with superior performance. It is anticipated that this review will provide a valuable insight into the rational design and synthesis of highly efficient Cu‐based electrocatalysts for large‐scale CRR utilization. [ABSTRACT FROM AUTHOR]

Electrochemical carbon dioxide (CO2) conversion technologies have become new favorites for addressing environmental and energy issues, especially with direct electrocatalytic reduction of CO2 (ECO2RR) and alkali metal‐CO2 (M–CO2) batteries as representatives. They are poised to create new economic drivers while also paving the way for a cleaner and more sustainable future for humanity. Although still far from practical application, ECO2RR has been intensively investigated over the last few years, with some achievements. In stark contrast, M–CO2 batteries, especially aqueous and hybrid M–CO2 batteries, offer the potential to combine energy storage and ECO2RR into an integrated system, but their research is still in the early stages. This article gives an insightful review, comparison, and analysis of recent advances in ECO2RR and M–CO2 batteries, illustrating their similarities and differences, aiming to advance their development and innovation. Considering the crucial role of well‐designed functional materials in facilitating ECO2RR and M–CO2 batteries, special attention is paid to the development of rational design strategies for functional materials and components, such as electrodes/catalysts, electrolytes, and membranes/separators, at the industrial level and their impact on CO2 conversion. Moreover, future perspectives and research suggestions for ECO2RR and M–CO2 batteries are presented to facilitate practical applications. [ABSTRACT FROM AUTHOR]

The large concentration of carbon dioxide (CO2) in the atmosphere can be utilized in industrial production using effective electrocatalysts such as metal‐organic frameworks (MOFs). Due to good properties such as high surface area, designable functionality, and uniform constitution, MOFs are regarded as promising electrocatalysts for the carbon dioxide electrochemical reduction reaction (eCO2RR). This review covers the importance, challenges, and mechanism of eCO2RR, and simply discusses the progress in the synthesis methods and characterization of MOFs. The review also thoroughly discusses the advances of single metal‐based MOFs, mixed metal‐based MOFs, and MOF derivatives as electrocatalysts for efficient eCO2RR. [ABSTRACT FROM AUTHOR]

Tandem catalysis presents a promising strategy to improve the selectivity toward multicarbon products in the electrocatalytic carbon dioxide reduction reaction (CO2RR). For CO2RR, CO is a critical intermediate for producing multicarbon products. However, the management of CO localization and CO diffusion remains underexplored despite its critical role. Herein, a 3D tandem catalyst electrode with silver nanoparticles (Ag NPs) is designed to generate CO as an intermediate product within a copper (Cu) nanoneedle array. Via this nanostructured design, CO2 forms C2+ products with a high Faradaic efficiency (FEC2+) of 64% in an H‐cell and 70% in a flow cell with a current density of 350 mA cm−2. These figures‐of‐merit are currently among the top literature reports. More importantly, in situ Raman spectroscopy and finite‐element method calculations are employed to elucidate the origins of enhanced selectivity. These approaches reveal the crucial role of prolonging the CO diffusion path length for improving CO utilization during CO2 conversion with tandem catalyst systems. The favorable CO2RR FEC2+ in two distinct environments (H‐cell and flow cell) further corroborates that this effect is not limited to a particular reactor environment. Overall, this study provides new insights for designing tandem catalysts for improved CO2RR selectivity to C2+ products. [ABSTRACT FROM AUTHOR]

Electrocatalytic CO2 reduction to valued products is a promising way to mitigate the greenhouse effect, as this reaction makes use of the excess CO2 in the atmosphere and at the same time forms valued fuels to partially fulfill the energy demand for human beings. Among these valued products, methane is considered a high-value product with a high energy density. This review systematically summarizes the recently studied reaction mechanisms for CO2 electroreduction to CH4. It guides us in designing effective electrocatalysts with an improved electrocatalytic performance. In addition, we briefly summarize the recent progress on CO2 electroreduction into CH4 from the instructive catalyst design, including catalyst structure engineering and catalyst component engineering, and then briefly discuss the electrolyte effect. Furthermore, we also provide a simplified techno-economic analysis of this technology. These summaries are helpful for beginners to rapidly master the contents related to the electroreduction of carbon dioxide to methane and also help to promote the further development of this field. [ABSTRACT FROM AUTHOR]

Electrochemical carbon dioxide reduction reaction (CO2RR) using clean electric energy provides a sustainable route to generate highly‐valuable chemicals and fuels, which is beneficial for realizing the carbon‐neutral cycle. Up to now, achieving a narrow product distribution and highly targeted product selectivity over Cu‐based electrocatalysts is still a big challenge. Herein, sulfur modification on different crystal planes of cuprous oxide (Cu2O) is demonstrated, results in an improvement for formate generation to different degrees. Experimental results and density functional theory (DFT) calculations reveal that sulfur species modified on the surface of Cu2O (100) facet effectively lower the formation energy of key intermediate *OCOH for formate generation compared with Cu2O (111) facet. As a consequence, the modification of p‐Block elements over Cu‐based electrocatalysts is an effective strategy to optimize the adsorption energy of key intermediate during CO2RR, leading to a highly selective product. [ABSTRACT FROM AUTHOR]

The electrocatalytic reduction of CO2 to other high value-added chemicals under ambient conditions is a promising and ecofriendly strategy to achieve sustainable carbon recycling. However, the CO2 reduction reaction (CO2RR) is still confronted with a large number of challenges, such as high reaction overpotential and low product selectivity. Therefore, the rapid development of appropriate electrocatalysts is the key to promoting CO2 electroreduction. Over the past few decades, Au-based nanocatalysts have been demonstrated to be promising for the selective CO2RR to CO owing to their low reaction overpotential, good product selectivity, high Faraday efficiency and inhibition of the hydrogen evolution reaction. In this respect, this review first introduces the fundamentals of the electrochemical reduction of CO2 and then focuses on recent accomplishments with respect to Au-based nanocatalysts for CO2RR. The manipulation of various factors, e.g., the nanoporous structure, nanoparticle size, composition, morphology, support and ligand, allows for the identification of several clues for excellent Au-based nanocatalysts. We hope that this review will offer readers some important insights on Au-based catalyst design and provide new ideas for developing robust electrocatalysts. [ABSTRACT FROM AUTHOR]

One of the most important current topics in the renewable and sustainable energy scenario is the CO2 electro‐reduction reaction (CO2RR), which is an alternative and important route for its conversion into various high value‐added chemicals, therefore making up a CO2 recycling process. Despite its importance and the works already developed in this field, many challenges still need to be overcome for CO2RR to reach high values of efficiency and selectivity. This is even more challenging considering that this reaction occurs with the transfer of several electrons, making the investigation and elucidation of the reaction mechanism a real need. Thus, several characterization techniques have been employed, and specially, the on‐line Electrochemical Mass Spectrometry (EC‐MS) technique emerges as a powerful tool, thus making possible to improve the understanding of reaction pathways, through the identification of products and intermediaries, and allowing the screening of electrocatalyst potentials for CO2RR. Herein, we present the evolution of adaptations of general electrochemical cell designs for the study of the CO2RR. [ABSTRACT FROM AUTHOR]

This paper presents the experimental investigation of copper loaded carbon nanotubes (CNTs) electrocatalysts for the electrochemical reduction of carbon dioxide. The electrocatalysts were synthesized by homogeneous deposition precipitation method (HDP) using urea as precipitating agent. The prepared catalysts were characterized by TEM, SEM, XRD, XPS, BET, and FTIR for their morphology and structure. Characterization results confirm the deposition of Cu nanoparticles (3-60 nm) on CNTs. Linear sweep voltammetry (LSV) and chronoamperometry (CA) were used to investigate the activity of the as-prepared catalysts for the electrochemical reduction of carbon dioxide. The electrocatalysts reduced CO2 with high current density in the potential range 0~-3V versus SCE (standard calomel electrode). Among all catalysts tested, 20 wt. % copper loaded CNTs showed maximum activity. Gas chromatograph with TCD was used to analyze liquid phase composition. The faradaic efficiency for methanol formation was estimated to be 38.5%. [ABSTRACT FROM AUTHOR]

Electrochemical CO2 reduction (CO2RR) is a key technology to convert greenhouse gas CO2 to value‐added products, such as CO and formic acid (HCOOH). In the present study, two‐dimensional Cu‐ and Al‐based layered double hydroxides (Cu−Al/LDHs) were applied as CO2RR catalysts. The catalysts were synthesized using a simple co‐precipitation method employing sodium carbonate solutions with different pH and synthesis temperatures. The elemental ratio of Cu and Al, and sheet size were controlled. The most active Cu−Al/LDH showed a faradaic efficiency for CO generation of 42 % and one for formate generation of 22 % at the current density of 50 mA using a gas diffusion electrode system under galvanostatic conditions. Our result indicates that the sheet size of the LDH sheet is a critical parameter for determining CO2RR activity. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of carbon dioxide (CO2ER) has attracted enormous research interest owing to the feasibility to consume the excessive CO2 in atmosphere arising from overconsumption of fossil fuels and store the chemical energy in value‐added chemicals. The conversion of CO2 into methane (CH4) is of great importance, and recent advance has allowed the design and utilisation of effective electrocatalysts with improved electrocatalytic performance regarding product selectivity and Faradaic efficiency. In this mini‐review, we discuss the recent progress and challenges of metal‐based heterogeneous electrocatalyst for CO2ER into CH4 by starting with fundamental mechanisms and designing principles of effective electrocatalysts. In the following sections, we present several successful demonstrations and analyze the effect and contribution arising from their chemical composition, facet, size, and other characters. Some challenges and promising strategies are discussed finally. [ABSTRACT FROM AUTHOR]

Herein, we report the controlled and direct fabrication of Cu2O/CuO thin film on the conductive nickel foam using electrodeposition route for the electrochemical reduction of carbon dioxide (CO2) to methanol. The electrocatalytic reduction was performed in CO2 saturated aqueous solution consisting of KHCO3, pyridine and HCl at room temperature. CO2 reduction was carried out at a constant potential of −1.3 V for 120 min to study the electrochemical performance of the prepared electrocatalysts. Cu2O/CuO shows better electrocatalytic activity with highest current density of 46 mA/cm2. The prepared catalyst can be an efficient and selective electrode for the production of methanol. [ABSTRACT FROM AUTHOR]

Electrochemical CO2 reduction (ECR) is highly attractive to curb global warming. The knowledge on the evolution of catalysts and identification of active sites during the reaction is important, but still limited. Here, we report an efficient catalyst (Ag-D) with suitable defect concentration operando formed during ECR within several minutes. Utilizing the powerful fast operando X-ray absorption spectroscopy, the evolving electronic and crystal structures are unraveled under ECR condition. The catalyst exhibits a ~100% faradaic efficiency and negligible performance degradation over a 120-hour test at a moderate overpotential of 0.7 V in an H-cell reactor and a current density of ~180 mA cm−2 at −1.0 V vs. reversible hydrogen electrode in a flow-cell reactor. Density functional theory calculations indicate that the adsorption of intermediate COOH could be enhanced and the free energy of the reaction pathways could be optimized by an appropriate defect concentration, rationalizing the experimental observation. Efficient electrocatalysts are crucial to the electrochemical carbon dioxide reduction. Here, the authors use the fast operando technique to explore a silver-based catalyst with improved catalytic performance benefiting from the suitable defect structures. [ABSTRACT FROM AUTHOR]

Development of efficient catalysts for selective electroreduction of CO2 to high-value products is essential for the deployment of carbon utilization technologies. Here we present a scalable method for preparing Cu electrocatalysts that favor CO2 conversion to C2+ products with faradaic efficiencies up to 72%. Grazing-incidence X-ray diffraction data confirms that anodic halogenation of electropolished Cu foils in aqueous solutions of KCl, KBr, or KI creates surfaces of CuCl, CuBr, or CuI, respectively. Scanning electron microscopy and energy dispersive X-ray spectroscopy studies show that significant changes to the morphology of Cu occur during anodic halogenation and subsequent oxide-formation and reduction, resulting in catalysts with a high density of defect sites but relatively low roughness. This work shows that efficient conversion of CO2 to C2+ products requires a Cu catalyst with a high density of defect sites that promote adsorption of carbon intermediates and C–C coupling reactions while minimizing roughness. Selective reduction of carbon dioxide to high-value products is key for advancing carbon capture and utilization technologies. Here the authors prepare a copper catalyst for electrocatalytic conversion of carbon dioxide to C2+ products with enhanced selectivity that is attributed to a high density of surface defects. [ABSTRACT FROM AUTHOR]

The electrochemical conversion of carbon dioxide (CO2) into value‐added chemicals is regarded as one of the promising routes to mitigate CO2 emission. A nitrogen‐doped carbon‐supported palladium (Pd) single‐atom catalyst that can catalyze CO2 into CO with far higher mass activity than its Pd nanoparticle counterpart, for example, 373.0 and 28.5 mA mg−1Pd, respectively, at −0.8 V versus reversible hydrogen electrode, is reported. A combination of in situ X‐ray characterization and density functional theory (DFT) calculation reveals that the PdN4 site is the most likely active center for CO production without the formation of palladium hydride (PdH), which is essential for typical Pd nanoparticle catalysts. Furthermore, the well‐dispersed PdN4 single‐atom site facilitates the stabilization of the adsorbed CO2 intermediate, thereby enhancing electrocatalytic CO2 reduction capability at low overpotentials. This work provides important insights into the structure‐activity relationship for single‐atom based electrocatalysts. [ABSTRACT FROM AUTHOR]

Electrochemical reduction of carbon dioxide (CO2) to CO is regarded as an efficient method to utilize the greenhouse gas CO2, because the CO product can be further converted into high value‐added chemicals via the Fisher–Tropsch process. Among all electrocatalysts used for CO2‐to‐CO reduction, Au‐based catalysts have been demonstrated to possess high selectivity, but their precious price limits their future large‐scale applications. Thus, simultaneously achieving high selectivity and reasonable price is of great importance for the development of Au‐based catalysts. Here, we report Ag@Au core–shell nanowires as electrocatalyst for CO2 reduction, in which a nanometer‐thick Au film is uniformly deposited on the core Ag nanowire. Importantly, the Ag@Au catalyst with a relative low Au content can drive CO generation with nearly 100 % Faraday efficiency in 0.1 m KCl electrolyte at an overpotential of ca. −1.0 V. This high selectivity of CO2 reduction could be attributed to a suitable adsorption strength for the key intermediate on Au film together with the synergistic effects between the Au shell and Ag core and the strong interaction between CO2 and Cl− ions in the electrolyte, which may further pave the way for the development of high‐efficiency electrocatalysts for CO2 reduction. [ABSTRACT FROM AUTHOR]

Two‐dimensional (2D) materials are attractive catalysts for the electrochemical reduction of carbon dioxide reaction (eCO2RR) by virtue of their tunable atomic structures, abundant active sites, enhanced conductivity, suitable binding affinity to carbon dioxide and/or reaction intermediates, and intrinsic scalability. Herein, recent advances in 2D catalysts for the eCO2RR are reviewed. Structural features and properties of 2D materials that contribute to their advanced electrocatalytic properties are summarized, and strategies for enhancing their activity and selectivity for the eCO2RR are reviewed. Prospects and challenges of applications of 2D catalysts for the eCO2RR on an industrial scale are highlighted. [ABSTRACT FROM AUTHOR]

It is of paramount importance to design and develop highly active and selective electrocatalysts for the CO2 reduction reaction. Herein, we obtained bismuth-based catalysts consisting of oxidized Bi2O2CO3 and metallic Bi featuring local shortened inter-layer Bi–Bi bonds from in situ reduction of bismuth oxyiodide (BiOI) microflowers, which showed over 90% formate faradaic efficiency in a wide negative potential region. [ABSTRACT FROM AUTHOR]

Abstract: CO2 electrochemical reduction offers a potential technique to decrease the CO2 emission levels, but it has been hindered by the poor performance of electrocatalysts. In this work, the electrochemical reduction of CO2 has been studied by using a needle‐like porous indium electrode, which was electrodeposited in aqueous electrolytes containing Cl− using the hydrogen bubble dynamic template. This novel electrode displayed improved electrocatalytic activity, enhanced conversion efficiencies, and a lower onset potential −0.76 V vs. RHE), which was 0.3 V less than the indium foil electrode. Moreover, it exhibited enhanced faradaic efficiencies of 86 % for formate at −0.86 V vs. RHE and with a current density of 5.8 mA cm−2. This excellent catalytic activity is the result of a large electrochemical surface area and needle‐like dendrite structures in the presence of Cl− salts. Utilization of the novel nanostructured electrocatalysts and understanding of the role of salts can contribute to further improvements in CO2 reduction. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of the first catalytic manganese N-heterocyclic carbene complexes are reported: MnBr( N-methyl- N′-2-pyridylbenzimidazol-2-ylidine)(CO)3 and MnBr( N-methyl- N′-2-pyridylimidazol-2-ylidine)(CO)3. Both new species mediate the reduction of CO2 to CO following two-electron reduction of the MnI center, as observed with preparative scale electrolysis and verified with 13CO2. The two-electron reduction of these species occurs at a single potential, rather than in two sequential steps separated by hundreds of millivolts, as is the case for previously reported MnBr(2,2′-bipyridine)(CO)3. Catalytic current enhancement is observed at voltages similar to MnBr(2,2′-bipyridine)(CO)3. [ABSTRACT FROM AUTHOR]

The copper-based catalyst is considered to be the only catalyst for electrochemical carbon dioxide reduction to produce a variety of hydrocarbons, but its low selectivity and low current density to C2 products restrict its development. Herein, a core-shell xZnO@yCu2O catalysts for electrochemical CO2 reduction was fabricated via a two-step route. The high selectivity of C2 products of 49.8% on ZnO@4Cu2O (ethylene 33.5%, ethanol 16.3%) with an excellent total current density of 140.1 mA cm−2 was achieved over this core-shell structure catalyst in a flow cell, in which the C2 selectivity was twice that of Cu2O. The high electrochemical activity for ECR to C2 products was attributed to the synergetic effects of the ZnO core and Cu2O shell, which not only enhanced the selectivity of the coordinating electron, improved the HER overpotential, and fastened the electron transfer, but also promoted the multielectron involved kinetics for ethylene and ethanol production. This work provides some new insights into the design of highly efficient Cu-based electrocatalysts for enhancing the selectivity of electrochemical CO2 reduction to produce high-value C2 products. [ABSTRACT FROM AUTHOR]

Electrochemical carbon dioxide reduction reaction (CO2RR) provides a promising pathway for both decreasing atmospheric CO2 concentration and producing valuable carbon‐based fuels. To explore efficient and cost‐effective catalysts for electrochemical CO2RR is of great importance, but remains challenging. Se‐doped carbon nanosheets (Se‐CNs) with a micro‐, meso‐, and macroporous structure are proposed for electrochemical CO2RR. Such an electrocatalyst combines the advantages of Se optimized active sites, hierarchical pores for facilitating reactant or ion penetration, transport and reaction, and large surface area for more accessible active sites. This Se‐CNs electrocatalyst exhibits over 11‐times enhanced partial current density of CO than the CNs without Se doping and high selectivity (90%) for CO2 electroreduction to CO at a low potential of −0.6 V versus the reversible hydrogen electrode (vs RHE). Density function theoretical calculations reveal that the Se introduction in CNs lowers the free energy barrier of CO2RR and inhibits hydrogen evolution reaction effectively, thus improving the selectivity for CO2 reduction to CO. This work presents a new member of the metal‐free electrocatalyst family, which is easily prepared, low cost, adjustable, and highly efficient for CO2RR. [ABSTRACT FROM AUTHOR]

The large‐scale application of electrochemical reduction of CO2, as a viable strategy to mitigate the effects of anthropogenic climate change, is hindered by the lack of active and cost‐effective electrocatalysts that can be generated in bulk. To this end, SnO2 nanoparticles that are prepared using the industrially adopted flame spray pyrolysis (FSP) technique as active catalysts are reported for the conversion of CO2 to formate (HCOO−), exhibiting a FEHCOO− of 85% with a current density of −23.7 mA cm−2 at an applied potential of −1.1 V versus reversible hydrogen electrode. Through tuning of the flame synthesis conditions, the amount of oxygen hole center (OHC; SnO●) is synthetically manipulated, which plays a vital role in CO2 activation and thereby governing the high activity displayed by the FSP‐SnO2 catalysts for formate production. The controlled generation of defects through a simple, scalable fabrication technique presents an ideal approach for rationally designing active CO2 reduction reactions catalysts. [ABSTRACT FROM AUTHOR]

External fields are introduced to catalytic processes to improve catalytic activities. The light field effect plays an important role in electrocatalytic processes, but is not fully understood. Here we report a series of photo-coupled electrocatalysts for CO2 reduction by mimicking the structure of chlorophyll. The porphyrin-Au catalyst exhibits a high turnover frequency of 37,069 h−1 at −1.1 V and CO Faradaic efficiency (FE) of 94.2% at −0.9 V. Under visible light, the electrocatalyst reaches similar turnover frequency and FE with potential reduced by ~ 130 mV. Interestingly, the light-induced positive shifts of 20, 100, and 130 mV for porphyrin-Co, porphyrin-Cu, and porphyrin-Au electrocatalysts are consistent with their energy gaps of 0, 1.5, and 1.7 eV, respectively, suggesting the porphyrin not only serves as a ligand but also as a photoswitch to regulate electron transfer pathway to the metal center. The light field effect can improve performance in electrocatalytic processes, but is not fully understood. Here the authors design a photo-coupled electrocatalyst using a porphyrin ligand as a photosensitizer and a coordinated metal as a catalytically active site for carbon dioxide reduction. [ABSTRACT FROM AUTHOR]

Electrochemical CO2 reduction reaction (CO2RR) provides a potential pathway to mitigate challenges related to CO2 emissions. Pd nanoparticles have shown interesting properties as CO2RR electrocatalysts, while how different facets of Pd affect its performance in CO2 reduction to synthesis gas with controlled H2 to CO ratios has not been understood. Herein, nanosized Pd cubes and octahedra particles dominated by Pd(100) and Pd(111) facets are, respectively, synthesized. The Pd octahedra particles show higher CO selectivity (up to 95%) and better activity than Pd cubes and commercial particles. For both Pd octahedra and cubes, the ratio of H2/CO products is tunable between 1 and 2, a desirable ratio for methanol synthesis and the Fischer–Tropsch processes. Further studies of Pd octahedra in a 25 cm2 flow cell show that a total CO current of 5.47 A is achieved at a potential of 3.4 V, corresponding to a CO partial current density of 220 mA cm−2. In situ X‐ray absorption spectroscopy studies show that regardless of facet Pd is transformed into Pd hydride (PdH) under reaction conditions. Density functional theory calculations show that the reduced binding energies of CO and HOCO intermediates on PdH(111) are key parameters to the high current density and Faradaic efficiency in CO2 to CO conversion. Pd cubic and octahedral nanoparticles dominated by Pd(100) and Pd(111) facets, respectively, are synthesized and evaluated for electrochemical CO2 reduction to synthesis gas. Experimental observations and density functional theory calculations demonstrate that the reduced binding energies of CO and HOCO intermediates on in situ formed PdH(111) correlate to the high current density and Faradaic efficiency in CO2 conversion. [ABSTRACT FROM AUTHOR]

Metal–carbon–carbon nanofibers composites obtained by catalytic pyrolysis of urban plastic residues have been prepared using Fe, Co or Ni as pyrolitic catalysts. The composite materials have been fully characterized from a textural and chemical point of view. The proportion of carbon nanofibers and the final content of carbon phases depend on the used pyrolitic metal with Ni being the most active pyrolitic catalysts. The composites show the electro-catalyst activity in the CO2 reduction to hydrocarbons, favoring all the formation of C1 to C4 hydrocarbons. The tendency of this activity is in accordance with the apparent faradaic efficiencies and the linear sweep voltammetries. The cobalt-based composite shows high selectivity to C3 hydrocarbons within this group of compounds. [ABSTRACT FROM AUTHOR]