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The electrochemical CO2 reduction reaction (eCO2RR) to multicarbon products has been widely recognized for Cu‐based catalysts. However, the structural changes in Cu‐based catalysts during the eCO2RR pose challenges to achieving an in‐depth understanding of the structure–activity relationship, thereby limiting catalyst development. Herein, we employ constant‐potential density functional theory calculations to investigate the sintering process of Cu single atoms of Cu−N−C single‐atom catalysts into clusters under eCO2RR conditions. Systematic constant‐potential ab initio molecular dynamics simulations revealed that the leaching of Cu−(CO)x moieties and subsequent agglomeration into clusters can be facilitated by synergistic adsorption of H and eCO2RR intermediates (e.g. CO). Increasing the Cu2+ concentration or the applied potential can efficiently suppress Cu sintering. Both microkinetic simulations and experimental results further confirm that sintered Cu clusters play a crucial role in generating C2 products. These findings provide significant insights into the dynamic evolution of Cu‐based catalysts and the origin of their activity toward C2 products during the eCO2RR. [ABSTRACT FROM AUTHOR]

This study proposes a straightforward strategy utilizing metal–organic frameworks (MOFs) to obtain efficient electrocatalysts for synthesizing C2 products (C2H4 and C2H5OH) via a CO2 reduction reaction. Cu-MOF-74 was chosen as the precursor, while copper oxide nanoparticles were obtained through a calcination method. During the calcination process, by controlling the calcination conditions, the porous structure of the MOF framework was successfully retained, leading to CuO-400 with a high catalytic activity and C2 production efficiency. Compared to CuO-n formed by the calcination of Cu(NO3)2, CuO-400 derived from MOFs exhibits a 1.6 times higher C2 activity as an electrocatalytic material at −1.15 V vs. RHE. [ABSTRACT FROM AUTHOR]

Designing catalysts with highly active, selectivity, and stability for electrocatalytic CO2 to formate is currently a severe challenge. Herein, we developed an electronic structure engineering on carbon nano frameworks embedded with nitrogen and sulfur asymmetrically dual-coordinated indium active sites toward the efficient electrocatalytic CO2 reduction reaction. As expected, atomically dispersed In-based catalysts with In-S1N3 atomic interface with asymmetrically coordinated exhibited high efficiency for CO2 reduction reaction (CO2RR) to formate. It achieved a maximum Faradaic efficiency (FE) of 94.3% towards formate generation at −0.8 V vs. reversible hydrogen electrode (RHE), outperforming that of catalysts with In-S2N2 and In-N4 atomic interface. And at a potential of −1.10 V vs. RHE, In-S1N3 achieves an impressive Faradaic efficiency of 93.7% in flow cell. The catalytic performance of In-S1N3 sites was confirmed to be enhanced through in-situ X-ray absorption near-edge structure (XANES) measurements under electrochemical conditions. Our discovery provides the guidance for performance regulation of main group metal catalysts toward CO2RR at atomic scale. [ABSTRACT FROM AUTHOR]

Electrocatalytic CO2‐to‐formate conversion is considered an economically viable process. In general, Zn‐based nanomaterials are well‐known to be highly efficient electrocatalysts for the conversion of CO2 to CO, but seldom do they exhibit excellent selectivity toward formate. In this article, we demonstrate that a heterointerface catalyst ZnO/ZnSnO3 with nanosheet morphology shows enhanced selectivity with a maximum Faradaic efficiency (FE) of 86% at −0.9 V versus reversible hydrogen electrode and larger current density for the conversion of CO2 to formate than pristine ZnO and ZnSnO3. In particular, the FEs of the C1 products (CO + HCOO−) exceed 98% over the potential window. The experimental measurements combined with theoretical calculations revealed that the ZnO in ZnO/ZnSnO3 heterojunction delivers the valence electron depletion and accordingly optimizes Zn d‐band center, which results in moderate Zn–O hybridization of HCOO* and weakened Zn–C hybridization of competing COOH*, thus greatly boosting the HCOOH generation. Our study highlights the importance of charge redistribution in catalysts on the selectivity of electrochemical CO2 reduction. [ABSTRACT FROM AUTHOR]

Conversion of carbon dioxide (CO2) to valuable chemicals and feedstocks through electrochemical reduction holds promise for achieving carbon neutrality and mitigating global warming. C2+ products are of interest due to their higher economic value. Since the CO2 to C2+ conversion process involves multiple steps, tandem catalytic strategies are commonly employed in the design of electrochemical CO2 reduction reaction (CO2RR) catalysts and systems/reactors. Among the diverse catalysts that are capable of reducing CO2 to CO, Cu stands out for more efficiently further converting CO to C2+ products. In this review, the emerging Cu‐based tandem catalysts and their impact on CO2RR performance, focusing on three positional relationships are summarized. It delves into the integration of tandem catalytic strategies into membrane electrolyzers, utilizing catalyst‐coated substrate (CCS) and catalyst‐coated membrane (CCM) technologies. Several typical examples are presented to illustrate this integration. Finally, the challenges and prospects of applying tandem strategies in the development of CO2RR catalysts/systems, as well as their device‐level implementation are indicated. [ABSTRACT FROM AUTHOR]

The electrochemical CO2 reduction reaction (CO2RR) has received widespread attention as a promising method for producing sustainable chemicals and mitigating the global warming. Here, we demonstrate a general and facile synthetic route for the metal-nitrogen-carbon (M-N-C) type catalyst by simply calcinating metal acetate and urea with commercial carbon black, which have potential application in CO2RR. The synthesized Ni−NC−600 catalyst has the structure of single Ni atom coordinated with one N atom and three C atoms (Ni−N1C3), which is suggested by X-ray absorption spectroscopy. The Ni−NC−600 catalyst exhibits high CO2RR catalytic performance and a high CO Faraday efficiency above 98% in a wide potential range from −0.7 to −1.3 V (vs. reversible hydrogen electrode (RHE)), superior to most of the reported Ni−N−C catalysts. This work has developed a facile strategy to synthesize high performance CO2RR catalyst. [ABSTRACT FROM AUTHOR]

Tandem catalysis, capable of decoupling individual steps, provides a feasible way to build a high-efficiency CO2 electroconversion system for multicarbons (C2+). The construction of electrocatalytic materials is one of focusing issues. Herein, we fabricated a single atom involved multivalent oxide-derived Cu composite material and found it inclined to reconstruct into oxygen-deficient multiphase Cu based species hybridized with monatomic Ni on N doped C matrix. In this prototype, rapid CO generation and C–C coupling are successively achieved on NiN4 sites and surface amorphized Cu species with defects, resembling a micro-production line. In this way, the in situ formed tandem catalyst exhibited a high Faradaic efficiency (FE) of ∼ 78% for C2+ products along with satisfactory durability over 50 h. Particularly, the reconstruction-induced amorphous layer with abundant asymmetric sites should be favorable to improve the ethanol selectivity (FE: 63%), which is about 10 times higher than that of the non-tandem Cu-based contrast material. This work offers a new approach for manipulating tandem catalyst systems towards enhancing C2+ products. [ABSTRACT FROM AUTHOR]

Developing highly efficient single-atom catalysts (SACs) for electrocatalytic carbon dioxide reduction reaction (CO2RR) is a promising approach to promoting carbon neutrality. However, challenges such as low activity, selectivity and high costs hinder industrial scaling, attributed to the lack of innate activity or insufficient transition metal (TM) active site density in current catalysts. Therefore, the focus of CO2RR research remains on developing SACs with intrinsic catalytic activity, high TM coverage and cost-effectiveness. This study presents the design of carbon-based materials with ultra-high TM coverage (TM2C12) (TM = Mo, Ru, Rh, W, Re, Os and Ir) as electrocatalyst SACs for CO2RR using density functional theory calculations. Among these materials, W2C12 (W represents tungsten) demonstrates superior selectivity and catalytic activity for CO2RR to carbon monoxide (CO) products with overpotentials of 0.45 V and a W coverage of up to 71.84 wt%. To further enhance its catalytic activity, non-metallic (NM) coordination modification (NM = B, N, O, P doping and C vacancy) was explored on W2C12. The results indicate that N-doped W2C12 (N-W2C12) can significantly improve selectivity and catalytic activity, achieving an extremely low overpotential of 0.34 V. This research offers valuable insights into designing SACs with high activity, selectivity and stability for CO2RR and other catalytic reactions.

The carbon dioxide reduction reaction (CO2RR) is one of the most promising solutions for realizing carbon neutralization via converting the emitted CO2 into value‐added chemicals. The CC coupling step for CO dimerization is the rate‐determining step for C2 pathways, which have not been thoroughly investigated. Herein, the direct cation stabilization effects on CO dimerization for *OCCO formation on the representative Cu(100) and Pt(100) surfaces are investigated. Density functional theory calculations show that the presence of alkali metal ions plays a vital role in promoting the coupling of *CO monomers on both metal surfaces, where Cu shows a stronger stabilization effect. More importantly, a strong linear correlation (R2 ≈ 0.9) between the dimer stabilization energy and the reaction energy is revealed for the first time, which is a promising indicator for the selectivity of C2 pathways. Further investigations on electronic structures reveal that the promoting effect on *OCCO formation is strongly related to the negative charges of the molecules, in which the negative charge accumulation is favored by the directional electron transfer due to the chemisorption of *OCCO on Cu(100) surface. This work offers insights into the understanding of CC coupling reactions for CO2RR mechanisms.

Highlights The advancement and current status of dual-atom catalysts are reported. The synergistic effects exhibited by recent dual-atom catalysts in mechanistic studies are classified and summarized. Challenges and prospects of dual-atom catalysts in synthesis, characterization, applications, and theory are discussed.

To avoid carbonate precipitation for CO2 electrolysis, developing CO2 conversion in an acid electrolyte is viewed as an ultimately challenging technology. In Nature, Xia et al. recently explored a proton-exchange membrane system for reducing CO2 to formic acid with a Pb-- PbSO4 composite catalyst derived from waste lead-acid batteries based on the lattice carbon activation mechanism. Up to 93% Faradaic effi- ciency was realized when formic acid was produced by this technology. [ABSTRACT FROM AUTHOR]

Copper (Cu) remains the most important metal catalyst for the carbon dioxide reduction reaction (CO2 RR) into C2 products. Due to limited evidence from in situ experiments, mechanistic studies are often performed in the framework of density functional theory (DFT), using functionals at the generalized gradient approximation (GGA) level, which have fundamental difficulties to correctly describe CO adsorption and surface stability. We employ the adiabatic connection fluctuation dissipation theorem within the random phase approximation (RPA), in combination with the linearized Poisson-Boltzmann equation to describe solvation effects, to investigate the mechanism of CO2 RR on the Cu(100) facet. Qualitatively different from the DFT-GGA results, RPA results propose the formation of *OCCHO as the potential determining step towards C2 products. The results suggest that it is important to use more accurate methods like RPA when modeling reactions involving multiple CO-related species like CO2 RR.

Electrochemical conversion of CO2 into formate is a promising strategy for mitigating the energy and environmental crisis, but simultaneously achieving high selectivity and activity of electrocatalysts remains challenging. Here, we report low-dimensional SnO2 quantum dots chemically coupled with ultrathin Ti3C2Tx MXene nanosheets (SnO2/MXene) that boost the CO2 conversion. The coupling structure is well visualized and verified by high-resolution electron tomography together with nanoscale scanning transmission X-ray microscopy and ptychography imaging. The catalyst achieves a large partial current density of -57.8 mA cm-2 and high Faradaic efficiency of 94% for formate formation. Additionally, the SnO2/MXene cathode shows excellent Zn-CO2 battery performance, with a maximum power density of 4.28 mW cm-2, an open-circuit voltage of 0.83 V, and superior rechargeability of 60 h. In situ X-ray absorption spectroscopy analysis and first-principles calculations reveal that this remarkable performance is attributed to the unique and stable structure of the SnO2/MXene, which can significantly reduce the reaction energy of CO2 hydrogenation to formate by increasing the surface coverage of adsorbed hydrogen.

Atomically dispersed Co‐N4‐based catalysts have been recently emerging as one of the most promising candidates for facilitating CO2 reduction reaction (CO2RR). The local electronic environment of Co‐N4 sites in these catalysts is considered to play a critical role in adjusting the catalytic performance, the effort of which however is not yet clearly verified. Herein, a series of cobalt phthalocyanines with different peripheral substituents including unsubstituted phthalocyanine Co(II) (CoPc), 2,9,16,23‐tetramethoxyphthalocyaninato Co(II) (CoPc‐4OCH3), and 2,9,16,23‐tetranitrophthalocyaninato Co(II) (CoPc‐4NO2) are supported onto the surface of the multi‐walled carbon nanotubes (CNTs), affording CoPc@CNTs, CoPc‐4OCH3@CNTs, and CoPc‐4NO2@CNTs. X‐ray photoelectron spectroscopy and X‐ray absorption near‐edge structure measurements disclose the influence of the peripheral substituents on the local electronic structure of Co atoms in these three catalysts. Electrochemical tests indicate the higher CO2RR performance of CoPc‐4OCH3@CNTs compared to CoPc@CNTs and CoPc‐4NO2@CNTs as exemplified by the higher Faraday efficiency of CO, larger part current densities, and better stability displayed by CoPc‐4OCH3@CNTs at the applied voltage range from −0.6 to −1.0 V versus RHE in both H‐cell and flow cell. These results highlight the effect of the electron‐donating ‐OCH3 substituent on the enhanced catalytic activity of CoPc‐4OCH3@CNTs, which will help develop Co‐N4‐based catalysts with promising catalytic performance toward CO2RR. [ABSTRACT FROM AUTHOR]

Cu‐based catalysts have been identified as the most promising candidates for generation of C2+ products in electrochemical CO2 reduction reaction. Defect engineering in catalysts is a widely employed strategy for promoting C−C coupling on Cu. However, comprehensive understanding of defect structure‐to‐activity relationship has not been obtained. In this study, controllable defects generation is achieved, which leads to a series of Cu‐based catalysts with various phase mixing degrees. It is observed that the Faradaic efficiency toward C2+ products increases with the phase mixing degree, reaching 81 % at maximum. In situ infrared absorption spectroscopy reveals that the catalysts with higher phase mixing degree tend to form *CO more easily and possess higher retention of *CO under high overpotential window, thereby promoting C−C coupling. This work sheds new light on the relationship between defects and C−C coupling, and the rational developed of more advanced Cu‐base catalysts. [ABSTRACT FROM AUTHOR]

Integrating plasmonic features as an emerging strategy for enhancing electrocatalysis for the carbon dioxide reduction reaction (CO2RR). The key parameters responsible for the enhanced electrocatalysis performance are the local heating, the hot carriers, and near‐field enhancement induced by localized surface plasmon resonance (LSPR, that is, plasmonic) excitation. This review provides a concise overview of the fundamental mechanism of CO2RR, detailing the generation and decay of plasmonic and the energy transfer dynamics between plasmonic nanostructures and adsorbates. It further involves recent progress in plasmonic‐assisted electrocatalysis for CO2RR, including experimental and theoretical research to decipher plasmonic mechanisms. Finally, it ends with an insightful discussion of the existing challenges and potential future directions in this field. [ABSTRACT FROM AUTHOR]

Plasmon‐mediated electrocatalysis that rests on the ability of coupling localized surface plasmon resonance (LSPR) and electrochemical activation, emerges as an intriguing and booming area. However, its development seriously suffers from the entanglement between the photoelectronic and photothermal effects induced by the decay of plasmons, especially under the influence of applied potential. Herein, using LSPR‐mediated CO2 reduction on Ag electrocatalyst as a model system, we quantitatively uncover the dominant photoelectronic effect on CO2 reduction reaction over a wide potential window, in contrast to the leading photothermal effect on H2 evolution reaction at relatively negative potentials. The excitation of LSPR selectively enhances the CO faradaic efficiency (17‐fold at −0.6 VRHE) and partial current density (100‐fold at −0.6 VRHE), suppressing the undesired H2 faradaic efficiency. Furthermore, in situ attenuated total reflection‐surface enhanced infrared absorption spectroscopy (ATR‐SEIRAS) reveals a plasmon‐promoted formation of the bridge‐bonded CO on Ag surface via a carbonyl‐containing C1 intermediate. The present work demonstrates a deep mechanistic understanding of selective regulation of interfacial reactions by coupling plasmons and electrochemistry. [ABSTRACT FROM AUTHOR]

Selective electrochemical CO2 reduction reaction (CO2RR) into value‐added hydrocarbon products such as C2H4 provides a sustainable approach to producing carbon chemicals, which however remains a great challenge owing to the multi‐electron transfer process during CO2 electroreduction. Herein, a tandem catalyst a‐Ni/Cu‐NP@CMK is developed by encapsulating Cu nanoparticles (Cu NPs) into hydrophobic cubic mesoporous carbon with doped atomic Ni‐N4 moieties. Electrochemical tests demonstrate the outstanding C2H4 selectivity of a‐Ni/Cu‐NP@CMK with a high Faraday efficiency (FE) of 72.3% for C2H4 at a large current density of 406.1 mA cm−2 in a flow cell under a neutral medium. Moreover, when used as the cathode catalyst in membrane electrode assembly, a‐Ni/Cu‐NP@CMK stably delivers a current density of 200 mA cm−2 with a FEC2H4 of 63% at ‐2.8 V for 30 h, providing a full‐cell energy efficiency of 28.3% for C2H4 production. Comparative studies disclose that the hydrophobic microenvironment of the Cu NPs in a‐Ni/Cu‐NP@CMK successfully suppresses the competitive hydrogen evolution reaction and improves the CO2RR selectivity. Additionally, in situ spectroscopic investigations and theoretical calculations reveal that the efficient CO2‐to‐CO conversion on the Ni‐N4 moieties feeds Cu NPs with enriched adsorbed CO (*CO), which facilitates the C─C coupling between adjacent *CO to form C2H4. [ABSTRACT FROM AUTHOR]

The electrochemical reduction of CO2 into C2+ products represents a promising solution to completing the carbon cycle, thereby fostering a sustainable energy supply. Single‐atom electrocatalysts (SAECs) have garnered significant attention as efficient electrocatalysts for the CO2 reduction reaction. Herein, we carried out a first‐principles study on the mechanism of C−C bond formation on single‐Cu‐atom‐modified covalent triazine frameworks (Cu‐CTFs), which are a promising platform for SAECs. Static density functional calculations indicated that the dimerization of CO, which is the main mechanism for C−C bond formation on bulk Cu metals, was not favorable for Cu‐CTFs because of the lack of adjacent Cu sites for co‐adsorption of CO molecules. Rather than CO dimerization, the reaction between adsorbed *CHO and CO to produce *COCHO has a relatively low reaction energy barrier. Constrained ab initio molecular dynamics analyses revealed that the C−C bond‐forming reaction proceeds via insertion of CO at the *CHO intermediate, which has a modest activation energy of 0.09 eV. Specifically, when CO molecule is constrained to be brought close to *CHO, CO insertion between *CHO and Cu occurs at a C−C distance of 1.8 Å. This insertion reaction is the transition step for this C−C bond formation. [ABSTRACT FROM AUTHOR]

Catalysts involving post‐transition metals have shown almost invincible performance on generating formate in electrochemical CO2 reduction reaction (CO2RR). Conversely, Cu without post‐transition metals has struggled to achieve comparable activity. In this study, a sulfur (S)‐doped‐copper (Cu)‐based catalyst is developed, exhibiting excellent performance in formate generation with a maximum Faradaic efficiency of 92 % and a partial current density of 321 mA cm−2. Ex situ structural elucidations reveal the presence of abundant grain boundaries and high retention of S−S bonds from the covellite phase during CO2RR. Furthermore, thermodynamic calculations demonstrate that S−S bonds can moderate the binding energies with various intermediates, further improving the activity of the formate pathway. This work is significant in modifying a low‐cost catalyst (Cu) with a non‐metallic element (S) to achieve comparable performance to mainstream catalysts for formate generation in industrial grade. [ABSTRACT FROM AUTHOR]

Atomically dispersed catalysts with two active sites have attracted attention in recent years. The two different sites may act synergistically in catalytic reactions or one site as active site and another regulates it. In this work, rare earth (RE)‐based single‐atom combo catalyst BiY/CN (with Y penta‐coordinated) is synthesized and characterized carefully for electrochemical reduction of CO2 to formic acid for the first time. The state of active Bi and Y species in the prepared catalyst is proved by the extended X‐ray absorption fine structure spectra and aberration‐corrected high‐angle annular dark field scanning transmission electron microscopy. The comprehensive experimental results and density functional theory calculations show Y sites covered by hydroxyls not only avoid being poisoned by *HCO2 at working conditions, but also serve as a spectator to affect the charge state of Bi sites, promoting performance by facilitating the transformation of *HCO2 intermediate to HCOOH. This work provides a new perspective on RE elements in electrocatalytic carbon dioxide reactions in future studies. [ABSTRACT FROM AUTHOR]

Urea (H2NCONH2) is a commercially indispensable chemical as a fertilizer and starting material for the manufacture of many other products. Currently, commercial urea can be prepared with an energy‐consuming process by combining liquid ammonia (NH3) and liquid carbon dioxide (CO2) under high‐temperature and high‐pressure conditions. An alternative approach for synthesis of urea may involve electrochemical synthesis reactions that occur under aqueous and ambient conditions. Here, we propose synthesis of urea via nucleophilic addition reaction during an electrochemical CO2 reduction process in NH4HCO3‐containing electrolytes. The urea formation at a rate of 0.11 mmol g−1 h−1 was achieved on a polycrystalline Au electrode (area: 1 cm2) at a potential of −1.4 V (vs. saturated calomel electrode). Furthermore, the detailed investigations including in‐situ spectroscopic analysis and isotopic labeling characterization reveal the capability of producing urea could be mainly attributed to a spontaneous reaction between the NH3 molecule and the CO2⋅− intermediate. This study promotes the exploration of electrochemical synthesis of high‐value‐added products. [ABSTRACT FROM AUTHOR]

Addressing the limitations arising from the consistent catalytic behavior observed for various intermediates during the electrochemical carbon dioxide reduction reaction (CO2RR) poses a significant challenge in the optimization of catalytic activity. In this study, we aimed to address this challenge by constructing an asymmetric coordination Fe single atom catalyst (SCA) with a dynamically evolved structure. Our catalyst, consisting of a Fe atom coordinated with one S atom and three N atoms (Fe−S1N3), exhibited exceptional selectivity (CO Faradaic efficiency of 99.02 %) and demonstrated a high intrinsic activity (TOF of 7804.34 h−1), and remarkable stability. Using operando XAFS spectra and Density Functional Theory (DFT) calculations, we elucidated the self‐relaxation of geometric distortion and dynamic evolution of bond lengths within the catalyst. These structure changes enabled independent regulation of the *COOH and *CO intermediate adsorption energies, effectively breaking the linear scale relationship and enhancing the intrinsic activity of CO2RR. This study provides valuable insights into the dynamic evolution of SACs and paves the way for targeted catalyst designs aimed to disrupt the linear scaling relationships. [ABSTRACT FROM AUTHOR]

Converting CO2 to valuable chemicals at ambient conditions has been a topic of great interest due to the large impact of CO2 on global warming. Electrochemical CO2 reduction reaction (CRR) has been considered an effective method to produce valuable products at ambient conditions. Recently, there has been a special focus toward C2+ products, such as C2H4, C2H5OH, or C3H7OH, which have higher energy densities and large applications in chemical industries. Copper surfaces, especially those derived from its oxidized variant, have been experimentally found to be selective for C2 products. In this mini-review, we delve into the recent advances in theoretical calculations for molecular level understanding of the key step of C2 production, the carbon-carbon (CC) coupling reaction. We discuss various methods that have been developed to model the complex electrode surface, including the change in electrode potential, the effect of electrolytes, and intertwining reaction intermediates. We also present a detailed evaluation concerning the errors induced by the different approximations and the importance of solvation and asymmetric reaction environments for CC coupling. Lastly, we summarize with an outlook and possible future research direction, such as simulating experimental observables for vibrational and X-ray absorption spectra at electrode working conditions. [ABSTRACT FROM AUTHOR]

Over the last decade, the CO2 reduction reaction (CO2RR) has been increasingly exploited for the synthesis of high‐value raw materials in gaseous or liquid form, although no examples of CO2 fixation in nanoparticle systems have been demonstrated. Herein, CO2 fixation into solid nanomaterials by laser synthesis and processing of gold colloids in water, traditionally considered a green approach leading to ligand‐free nanoparticles without the formation of by‐products, is reported. If carbon monoxide‐rich gold nanoparticles are observable even after synthesis in deionized water, the presence of CO2 derivatives in alkaline water environment leads to C2 and C3 coupling with the production of carboxylic acids as a typical CO2RR fingerprint. While laser processing of preformed gold colloids is selective for C2 coupling, both C2 and C3 coupling to lactic acid are observed during pulsed laser ablation of a gold target. In the latter case, it is demonstrated that it is possible to synthesize photoluminescent organometallic nanocomposites in the blue spectral region with a quantum yield of about 20% under adequate experimental conditions. In this research, new pathways are offered to be explored in energetics, photonics, catalysis, and synthesis at the nanoscale.

Abstract A forward‐bias bipolar membrane (BPM) provides an alkaline cathode condition, which can be beneficial to some electrochemical reactions, such as the CO2 reduction reaction (CO2RR), but the water association (WA) in forward‐bias BPM is not well understood at all. In this study, BPMs are designed with different interfacial polymeric catalysts to investigate the WA reaction under forward‐bias for electrochemical applications. An enhanced current density is observed with added polymeric catalysts (−OH, −O−, −N−, and graphene oxide) compared to the blank control. Temperature‐dependent measurements indicated that the WA in BPM is not kinetically controlled. The in‐plane and through‐plane ions diffusion is investigated, which showed that the WA in BPM is limited mostly by the transport of OH− and, to a lesser degree, H+ at the interface. Molecular dynamic studies presented that the migration rate of OH− at the interface is approximately one order of magnitude lower than that of H+, indicating that the WA is mainly governed by the transport of OH−. Finally, a forward‐bias CO2RR electrolyzer is demonstrated with an Faradaic effeiciency CO (FECO) of 92.2 ± 2.7%. This work provides important fundamental insights into the WA reaction that would enable the use of forward‐bias BPM electrolyzers in future electrochemical applications.

Abstract Electrocatalytic CO2‐to‐formate conversion is considered an economically viable process. In general, Zn‐based nanomaterials are well‐known to be highly efficient electrocatalysts for the conversion of CO2 to CO, but seldom do they exhibit excellent selectivity toward formate. In this article, we demonstrate that a heterointerface catalyst ZnO/ZnSnO3 with nanosheet morphology shows enhanced selectivity with a maximum Faradaic efficiency (FE) of 86% at −0.9 V versus reversible hydrogen electrode and larger current density for the conversion of CO2 to formate than pristine ZnO and ZnSnO3. In particular, the FEs of the C1 products (CO + HCOO−) exceed 98% over the potential window. The experimental measurements combined with theoretical calculations revealed that the ZnO in ZnO/ZnSnO3 heterojunction delivers the valence electron depletion and accordingly optimizes Zn d‐band center, which results in moderate Zn–O hybridization of HCOO* and weakened Zn–C hybridization of competing COOH*, thus greatly boosting the HCOOH generation. Our study highlights the importance of charge redistribution in catalysts on the selectivity of electrochemical CO2 reduction.

Electrochemical reduction of CO2 (CO2RR) is expected to play a key role among the various strategies being explored to limit global warming. In this scenario, Layered Double Hydroxides (LDHs) are emerging as a promising class of electrocatalysts to replace the most used noble metals. In this work three Zn-Al LDH with different Zn2+/Al3+ ratio were synthesized and characterized by means of XRD, STEM-EDX and HR-TEM. Their suitability for CO2RR to CO was assessed by means of a custom-made three-compartment cell, showing an increase in CO selectivity by decreasing the Zn2+/Al3+ ratio. The CO2 interaction with the samples was firstly characterized by means of volumetric adsorption measurements, exhibiting an increase in capture capacity by decreasing the Zn2+/Al3+ ratio. The evolution of the samples in interaction with a CO2-saturated liquid flow was then deeply investigated by means of in-situ ATR-IR spectroscopy. The samples displayed a different evolution in the vibrational region of the carbonate-like species (1800–1200 cm−1). To better discriminate the different carbonate cyclohexane was also employed. A definitive assignment of the main IR bands of the carbonate was carried out by studying the spectral behavior of the different bands observed in the ATR-IR experiments and by comparing these results with the existing literature. Interestingly, Zn-Al 1:2 LDH, the most efficient electrocatalyst for CO2RR, is also the sole sample exhibiting a higher monodentate to total bidentate carbonates ratio, suggesting that the existence of a higher content of low coordination oxygen anions with stronger basic character can influence the final catalytic activity.

Abstract Conversion of carbon dioxide (CO2) to valuable chemicals and feedstocks through electrochemical reduction holds promise for achieving carbon neutrality and mitigating global warming. C2+ products are of interest due to their higher economic value. Since the CO2 to C2+ conversion process involves multiple steps, tandem catalytic strategies are commonly employed in the design of electrochemical CO2 reduction reaction (CO2RR) catalysts and systems/reactors. Among the diverse catalysts that are capable of reducing CO2 to CO, Cu stands out for more efficiently further converting CO to C2+ products. In this review, the emerging Cu‐based tandem catalysts and their impact on CO2RR performance, focusing on three positional relationships are summarized. It delves into the integration of tandem catalytic strategies into membrane electrolyzers, utilizing catalyst‐coated substrate (CCS) and catalyst‐coated membrane (CCM) technologies. Several typical examples are presented to illustrate this integration. Finally, the challenges and prospects of applying tandem strategies in the development of CO2RR catalysts/systems, as well as their device‐level implementation are indicated.

Highlights The novel hybrid structured nanofiber electrode, incorporating crushed nanofibers into the nanofiber network, is designed to effectively resolve the issue of insufficient interfacial bonding of porous nanofiber electrodes on solid electrolyte interfaces. The hybrid nanofibers are covered with in situ exsolved metal nanocatalysts to enhance CO2 reduction reaction rate. Electrochemical and microstructure 3D reconstruction analyses confirmed the hybrid structure’s efficiency in improving the contact area at the porous-solid interface, leading to an increase in reaction sites.

Highlights A unique atomic dispersed hetero-pair was successfully synthesized, consisting of Mo-Fe di-atoms anchored on N-doped carbon carrier. This strategy breaks the linear scaling relationships of electrocatalytic CO2 reduction by simultaneously regulating the *COOH adsorption energy and *CO desorption energy. The as-prepared MoFe–N–C exhibits excellent performance for CO2RR to CO with a high turnover frequency (TOF) of 3336.21 h−1, CO Faradaic efficiency (FECO) of 95.96% at − 0.60 V (versus RHE) and outstanding stability.

Abstract Integrating plasmonic features as an emerging strategy for enhancing electrocatalysis for the carbon dioxide reduction reaction (CO2RR). The key parameters responsible for the enhanced electrocatalysis performance are the local heating, the hot carriers, and near‐field enhancement induced by localized surface plasmon resonance (LSPR, that is, plasmonic) excitation. This review provides a concise overview of the fundamental mechanism of CO2RR, detailing the generation and decay of plasmonic and the energy transfer dynamics between plasmonic nanostructures and adsorbates. It further involves recent progress in plasmonic‐assisted electrocatalysis for CO2RR, including experimental and theoretical research to decipher plasmonic mechanisms. Finally, it ends with an insightful discussion of the existing challenges and potential future directions in this field.

Abstract The electrochemical reduction of CO2 into C2+ products represents a promising solution to completing the carbon cycle, thereby fostering a sustainable energy supply. Single‐atom electrocatalysts (SAECs) have garnered significant attention as efficient electrocatalysts for the CO2 reduction reaction. Herein, we carried out a first‐principles study on the mechanism of C−C bond formation on single‐Cu‐atom‐modified covalent triazine frameworks (Cu‐CTFs), which are a promising platform for SAECs. Static density functional calculations indicated that the dimerization of CO, which is the main mechanism for C−C bond formation on bulk Cu metals, was not favorable for Cu‐CTFs because of the lack of adjacent Cu sites for co‐adsorption of CO molecules. Rather than CO dimerization, the reaction between adsorbed *CHO and CO to produce *COCHO has a relatively low reaction energy barrier. Constrained ab initio molecular dynamics analyses revealed that the C−C bond‐forming reaction proceeds via insertion of CO at the *CHO intermediate, which has a modest activation energy of 0.09 eV. Specifically, when CO molecule is constrained to be brought close to *CHO, CO insertion between *CHO and Cu occurs at a C−C distance of 1.8 Å. This insertion reaction is the transition step for this C−C bond formation.

Highlights: The novel hybrid structured nanofiber electrode, incorporating crushed nanofibers into the nanofiber network, is designed to effectively resolve the issue of insufficient interfacial bonding of porous nanofiber electrodes on solid electrolyte interfaces. The hybrid nanofibers are covered with in situ exsolved metal nanocatalysts to enhance CO2 reduction reaction rate. Electrochemical and microstructure 3D reconstruction analyses confirmed the hybrid structure's efficiency in improving the contact area at the porous-solid interface, leading to an increase in reaction sites. The unique characteristics of nanofibers in rational electrode design enable effective utilization and maximizing material properties for achieving highly efficient and sustainable CO2 reduction reactions (CO2RRs) in solid oxide electrolysis cells (SOECs). However, practical application of nanofiber-based electrodes faces challenges in establishing sufficient interfacial contact and adhesion with the dense electrolyte. To tackle this challenge, a novel hybrid nanofiber electrode, La0.6Sr0.4Co0.15Fe0.8Pd0.05O3−δ (H-LSCFP), is developed by strategically incorporating low aspect ratio crushed LSCFP nanofibers into the excess porous interspace of a high aspect ratio LSCFP nanofiber framework synthesized via electrospinning technique. After consecutive treatment in 100% H2 and CO2 at 700 °C, LSCFP nanofibers form a perovskite phase with in situ exsolved Co metal nanocatalysts and a high concentration of oxygen species on the surface, enhancing CO2 adsorption. The SOEC with the H-LSCFP electrode yielded an outstanding current density of 2.2 A cm−2 in CO2 at 800 °C and 1.5 V, setting a new benchmark among reported nanofiber-based electrodes. Digital twinning of the H-LSCFP reveals improved contact adhesion and increased reaction sites for CO2RR. The present work demonstrates a highly catalytically active and robust nanofiber-based fuel electrode with a hybrid structure, paving the way for further advancements and nanofiber applications in CO2-SOECs. [ABSTRACT FROM AUTHOR]

[Display omitted] • DFT study for CO 2 electrochemical reduction to value-added products. • A novel dual chromium-anchored tri-vacancy borophene (Cr 2 /TV-β 12) electrocatalyst. • Study on twenty-eight different dual atom tri-vacant borophene electrocatalysts. • Limiting potential for CO 2 RR was −0.45 V, with the main product being formaldehyde. Carbon dioxide reduction reaction (CO 2 RR) to convert carbon dioxide (CO 2) into value-added products via the electrochemical method is a conducive way to tackle the hazard of high CO 2 emissions. The present DFT study reports a novel dual chromium-anchored tri-vacancy borophene (Cr 2 /TV-β 12) electrocatalyst, which showed high selectivity and stability for CO 2 RR. A tri-vacancy defect was introduced in β 12 borophene to create an 11-membered ring borophene sheet (TV-β 12), and 28 different electrocatalysts were explored via doping various transition metals (Co, Cr, Cu, Fe, Mn, Ni, Zn). Density functional theory simulation results revealed that the Cr 2 /TV-β 12 electrocatalyst adsorbs and activates CO 2 efficiently, which was validated by the partial density of states, charge density difference, Bader charge, and crystal orbital Hamilton population analyses. The limiting potential for CO 2 RR was evaluated to be −0.45 V, against hydrogen evolution reaction (HER) (0.57 V), with the main product being formaldehyde. The catalyst showed selectivity towards CO 2 reduction and suppressed HER. The usual problem of carbon monoxide poisoning encountered in CO 2 reduction was also assessed and a high resistance against the same was established. At the outset, the research revealed that dual atom-doped tri-vacancy β 12 borophene has tremendous potential to be utilized as an efficient catalyst for CO 2 RR. [ABSTRACT FROM AUTHOR]

Modulation of the microenvironment on the electrode surface is one of the effective means to improve the efficiency of electrocatalytic carbon dioxide reduction (eCO2RR). To achieve high conversion rates, the phase boundary at the electrode surface should be finely controlled to overcome the limitation of CO2 solubility in the aqueous electrolyte. Herein, we developed a simple and efficient method to structure electrocatalyst with a superhydrophobic surface microenvironment by one‐step co‐electrodeposition of Cu and polytetrafluoroethylene (PTFE) on carbon paper. The super‐hydrophobic Cu‐based electrode displayed a high ethylene (C2H4) selectivity with a Faraday efficiency (FE) of 67.3 % at −1.25 V vs. reversible hydrogen electrode (RHE) in an H‐type cell, which is 2.5 times higher than a regular Cu electrode without PTFE. By using PTFE as a surface modifier, the activity of eCO2RR is enhanced and water (proton) adsorption is inhibited. This strategy has the potential to be applied to other gas‐conversion electrocatalysts. [ABSTRACT FROM AUTHOR]

The electrochemical CO2 reduction reaction (CO2RR) presents a promising approach for producing valuable chemicals and fuels, offering a dual benefit in terms of environmental preservation and the efficient utilization of carbon resources. In this work, we proposed a stepwise electrodeposition method to prepare Cu−Pb bimetallic heterojunction catalyst on polyaniline‐modified carbon paper (PANI‐CuPb‐x), where x is the electrodeposition times(min). Among the studied catalysts, the electrode electrodeposited for 2 min (PANI‐CuPb‐2) exhibited a remarkable performance during the electrocatalysis CO2 to multicarbon (C2+) products process, achieving a Faraday efficiency (FE) of 81.46 % and a partial current density of 15.41 mA cm−2 at −1.2 V (vs. RHE) in an H‐type cell. The detailed study demonstrated that introducing Pb could effectively improve the formation of COOH*inhibit hydrogen evolution reaction (HER). Furthermore, the heterojunction structure in the catalysts facilitated C−C coupling of the generated C1 intermediate species, which enhanced the CO2 to C2+ reaction. [ABSTRACT FROM AUTHOR]

A catalyst layer is coated on the fuel electrode in a proton-conducting solid oxide electrolysis cell reactor, which can optimize electrochemical performance and expand the application range of the reactor. In this work, CuO–ZnO catalyst is prepared by oxalate co-precipitation method and combined with a single cell to obtain a reactor with the structure of La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (LSCF) ǀ BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ (BZCYYb) ǀ NiO-BZCYYb (active layer) ǀ NiO-BZCYYb (support layer) | CuO–ZnO (catalyst layer). The electrolysis current density of this reactor with humid air as oxidant and 20%CO 2 –80%H 2 as fuel is 2751 mA cm−2 under 1.3 V at 750 °C. It operates steadily for 138 h under 1.3 V electrolysis at 650 °C, which is better than the reactor without a catalyst layer under this condition. Additionally, CO and CH 4 are detected in the exhaust gas on the fuel electrode side, and the CO selectivity reaches over 90% at 750-550 °C. [Display omitted] • A Cu–Zn-PCEC reactor is fabricated for CO 2 reduction reaction. • The CO selectivity reaches over 90% at 750-550 °C of the Cu–Zn-PCEC reactor. • The electrolysis current density is 2751 mA cm−2 under 1.3 V at 750 °C. • Cu–Zn-PCEC reactor operates steadily for 138 h under 1.3 V electrolysis at 650 °C. [ABSTRACT FROM AUTHOR]

Electrochemical CO2 reduction reaction (CO2RR) has been recognized as an appealing route to remarkably accelerate the carbon‐neutral cycle and reduce carbon emissions. Notwithstanding great catalytic activity that has been acquired in neutral and alkaline conditions, the carbonates generated from the inevitable reaction of the input CO2 with the hydroxide severely lower carbon utilization and energy efficiency. By contrast, CO2RR in an acidic condition can effectively circumvent the carbonate issues; however, the activity and selectivity of CO2RR in acidic electrolytes will be decreased significantly due to the competing hydrogen evolution reaction (HER). Enriching the CO2 and the key intermediates around the catalyst surface can promote the reaction rate and enhance the product selectivity, providing a promising way to boost the performance of CO2RR. In this review, the catalytic mechanism and key technique challenges of CO2RR are first introduced. Then, the critical progress of enrichment strategies for promoting the CO2RR in the acidic electrolyte is summarized with three aspects: catalyst design, electrolyte regulation, and electrolyzer optimization. Finally, some insights and perspectives for further development of enrichment strategies in acidic CO2RR are expounded. [ABSTRACT FROM AUTHOR]

Context: The catalytic ability of Sc-doped C46 and Sc-doped Al23P23 as catalysts of CO2-RR to create the CH4 and CH3OH is investigated. The mechanisms of CO2-RR are examined by theoretical methods and ΔGreaction of reaction steps of CO2-RR mechanisms are calculated. The overpotential of CH4 and CH3OH production on Sc-doped C46 and Sc-doped Al23P23 is calculated. The Sc atoms of Sc-doped C46 and Sc-doped Al23P23 can adsorb the CO2 molecule as the first step of CO2-RR. The CH4 is produced from hydrogenation of *CH3O and the *CO → *CHO reaction step is the rate limiting step for CH4 production. The CH3OH can be formed on Sc-doped C46 and Sc-doped Al23P23 by *CO → *CHO → *CH2O → *CH3O → CH3OH mechanism and HCOOH → *CHO → *CH2O → *CH3O → CH3OH mechanism. The Sc-C46 and Sc-Al23P23 can catalyze the CO2-RR to produce the CH4 and CH3OH by acceptable mechanisms. Methods: Here, the structures are optimized by PW91PW91/6-311+G (2d, 2p) and M06-2X/cc-pVQZ methods in GAMESS software. The frequencies of nanocages and their complexes with species of CO2-RR are investigated by mentioned methods. The transition state of each reaction step of CO2-RR is searched by Berny method to find the CO2-RR intermediates. The ∆Eadsorption of intermediates of CO2-RR on surfaces of nanocages is calculated and the ∆Greaction of reaction steps of CO2-RR is calculated. [ABSTRACT FROM AUTHOR]

Here, the possible mechanisms for CO2 reduction reaction to produce the CO, CH4, HCOOH, HCHO and CH3OH species on surfaces of carbon and silicon Fullerenes (C50 and Si50) as catalysts are studied by theoretical and computational models. The calculated overpotential of CO2 reduction reaction on Ni-C50 and Ni-Si50 Fullerenes are lower than corresponding values on various metal catalysts, significantly. Results shown that rate limiting step for CH4 production on Ni-C50 and Ni-Si50 Fullerenes is the Fullerene-*CO → Fullerene-*CHO. Results indicated that the Ni-Si50 Fullerene has more negative ΔGreaction values than Ni-C50 Fullerenes to CH4 production, significantly. The calculated overpotential for CH4 and CH3OH production are lower than HCOOH and HCHO creation on Ni-C50 and Ni-Si50 Fullerenes. The Ni-C50 and Ni-Si50 Fullerenes can catalyze the processes of CO2 reduction reaction through possible mechanisms by theoretical and computational models. [ABSTRACT FROM AUTHOR]

Highlights: A unique atomic dispersed hetero-pair was successfully synthesized, consisting of Mo-Fe di-atoms anchored on N-doped carbon carrier. This strategy breaks the linear scaling relationships of electrocatalytic CO2 reduction by simultaneously regulating the *COOH adsorption energy and *CO desorption energy. The as-prepared MoFe–N–C exhibits excellent performance for CO2RR to CO with a high turnover frequency (TOF) of 3336.21 h−1, CO Faradaic efficiency (FECO) of 95.96% at − 0.60 V (versus RHE) and outstanding stability. Electrochemical carbon dioxide reduction reaction (CO2RR) involves a variety of intermediates with highly correlated reaction and ad-desorption energies, hindering optimization of the catalytic activity. For example, increasing the binding of the *COOH to the active site will generally increase the *CO desorption energy. Breaking this relationship may be expected to dramatically improve the intrinsic activity of CO2RR, but remains an unsolved challenge. Herein, we addressed this conundrum by constructing a unique atomic dispersed hetero-pair consisting of Mo-Fe di-atoms anchored on N-doped carbon carrier. This system shows an unprecedented CO2RR intrinsic activity with TOF of 3336 h−1, high selectivity toward CO production, Faradaic efficiency of 95.96% at − 0.60 V and excellent stability. Theoretical calculations show that the Mo-Fe diatomic sites increased the *COOH intermediate adsorption energy by bridging adsorption of *COOH intermediates. At the same time, d-d orbital coupling in the Mo-Fe di-atom results in electron delocalization and facilitates desorption of *CO intermediates. Thus, the undesirable correlation between these steps is broken. This work provides a promising approach, specifically the use of di-atoms, for breaking unfavorable relationships based on understanding of the catalytic mechanisms at the atomic scale. [ABSTRACT FROM AUTHOR]

Electrocatalysis for CO2 conversion has been extensively studied to mitigate the energy shortage and environmental issues, which are gaining ever‐increasing attention. However, the complicated CO2 reduction process and the dynamic evolution occurring on electrocatalyst surface make it hard to understand the catalytic mechanism. The development of advanced in situ/operando techniques intelligently coupled with electrochemical cells sheds light on the related study via capturing surface atomic rearrangement, tracing chemical state change of catalysts, monitoring the behavior of intermediates and products, and depicting microenvironment near the electrode surface. In this review, fundamentals of the state‐of‐the‐art in situ/operando techniques are clarified first. Case studies on the in situ/operando techniques performed to probe the CO2 reduction reaction processes are then discussed in detail. Finally, conclusions and outlook on this field are presented. [ABSTRACT FROM AUTHOR]