Electrochemical CO2 Reduction Reaction Research Articles

Switching CO2 Electroreduction toward Ethanol by Delocalization State-Tuned Bond Cleavage.

The electrochemical CO2 reduction reaction by copper-based catalysts features a promising approach to generate value-added multicarbon (C2+) products. However, due to the unfavored formation of oxygenate intermediates on the catalyst surface, the selectivity of C2+ alcohols like ethanol remains unsatisfactory compared to that of ethylene. The bifurcation point (i.e., the CH2═CHO* intermediate adsorbed on Cu via a Cu-O-C linkage) is critical to the C2+ product selectivity, whereas the subsequent cleavage of the Cu-O or the O-C bond determines the ethanol or ethylene pathway. Inspired by the hard-soft acid-base theory, in this work, we demonstrate an electron delocalization tuning strategy of the Cu catalyst by a nitrene surface functionalization approach, which allows weakening and cleaving of the Cu-O bond of the adsorbed CH2═CHO*, as well as accelerating hydrogenation of the C═C bond along the ethanol pathway. As a result, the nitrene-functionalized Cu catalyst exhibited a much-enhanced ethanol Faradaic efficiency of 45% with a peak partial current density of 406 mA·cm-2, substantially exceeding that of unmodified Cu or amide-functionalized Cu. When assembled in a membrane electrode assembly electrolyzer, the catalyst presented a stable CO2-to-ethanol conversion for >300 h at an industrial current density of 400 mA·cm-2.

Seeding Atomic Silver into Internal Lattice Sites of Transition Metal Oxide for Advanced Electrocatalysis.

Transition metal oxides (TMOs) are widely studied for loading of various catalysts due to their low cost and high structure flexibility. However, the prevailing close-packed nature of most TMOs crystals has restricted the available loading sites to surface only, while their internal bulk lattice remains unactuated due to the inaccessible narrow space that blocks out most key reactants and/or particulate catalysts. Herein, using tunnel-structured MnO2, this study demonstrates how TMO's internal lattice space can be activated as extra loading sites for atomic Ag in addition to the conventional surface-only loading, via which a dual-form Ag catalyst within MnO2 skeleton is established. In this design, not only faceted Ag nanoparticles are confined onto MnO2 surface by coherent lattice-sharing, Ag atomic strings are also seeded deep into the sub-nanoscale MnO2 tunnel lattice, enriching the catalytically active sites. Tested for electrochemical CO2 reduction reaction (eCO2RR), such dual-form catalyst exhibits a high Faradaic efficiency (94%), yield (67.3mol g-1 h-1) and durability (≈48h) for CO production, exceeding commercial Ag nanoparticles and most Ag-based electrocatalysts. Theoretical calculations further reveal the concurrent effect of such dual-form catalyst featuring facet-dependent eCO2RR for Ag nanoparticles and lattice-confined eCO2RR for Ag atomic strings, inspiring the future design of catalyst-substrate configuration.

Active Oxygenated Structure‐Intensified CO2 Capture Enables Efficient Electrochemical Ethylene Production Over Carbon Nanofibers

The pursuit of high efficacy C–C coupling during the electrochemical CO2 reduction reaction remains a tremendous challenge owing to the high energy barrier of CO2 activation and insufficient coverage of the desired intermediates on catalytic sites. Inspired by the concept of capture‐coupled CO2 activation, we fabricated quinone‐grafted carbon nanofibers via an in situ oxidative carbonylation strategy. The quinone functionality of carbon nanofibers promotes the capture of CO2 followed by activation. At a current density of 400 mA cm‐2, the Faradaic efficiency of ethylene reached 62.9%, and a partial current density of 295 mA cm‐2 was achieved on the quinone‐rich carbon nanofibers. The results of in situ spectroscopy and theoretical calculations indicated that the remarkable selectivity enhancement in ethylene originates from the quinone structure, rather than the electronic properties of Cu particles. The interaction of quinone with CO2 increases the local *CO coverage and simultaneously hinders the co‐adsorption of *H on Cu sites, which greatly reduces the energy barrier for C–C coupling and restrains subsequent *CO protonation. The modulation strategy involving specific oxygenated structure, as an independent degree of freedom, guides the design of functionalized carbon materials for tailoring the selectivity of desired products during the CO2 capture and reduction.

Active Oxygenated Structure-Intensified CO2 Capture Enables Efficient Electrochemical Ethylene Production Over Carbon Nanofibers.

The pursuit of high efficacy C-C coupling during the electrochemical CO2 reduction reaction remains a tremendous challenge owing to the high energy barrier of CO2 activation and insufficient coverage of the desired intermediates on catalytic sites. Inspired by the concept of capture-coupled CO2 activation, we fabricated quinone-grafted carbon nanofibers via an in situ oxidative carbonylation strategy. The quinone functionality of carbon nanofibers promotes the capture of CO2 followed by activation. At a current density of 400 mA cm-2, the Faradaic efficiency of ethylene reached 62.9%, and a partial current density of 295 mA cm-2 was achieved on the quinone-rich carbon nanofibers. The results of in situ spectroscopy and theoretical calculations indicated that the remarkable selectivity enhancement in ethylene originates from the quinone structure, rather than the electronic properties of Cu particles. The interaction of quinone with CO2 increases the local *CO coverage and simultaneously hinders the co-adsorption of *H on Cu sites, which greatly reduces the energy barrier for C-C coupling and restrains subsequent *CO protonation. The modulation strategy involving specific oxygenated structure, as an independent degree of freedom, guides the design of functionalized carbon materials for tailoring the selectivity of desired products during the CO2 capture and reduction.

CAIMD Simulations Guided Design of Atomic Praseodymium Doping In–Bi Nanofibers for High‐Energy‐Efficiency CO2 Electrolysis to Formate in Ultra‐Wide Potential Window

AbstractThe electrochemical CO2 reduction reaction (ECO2RR) has emerged as a promising technology for achieving carbon neutralization. Even though considerable efforts are dedicated to gain deep insight into the understanding of ECO2RR on a mechanism level through density functional theory (DFT) studies, effects of solvent molecules and temperature have long been neglected by conventional DFT calculations as a consequence of limitations in current technologies and computational power of supercomputers. Under this context, the lack of comprehensive understanding over the energy changes in the reaction derived from the only concern on free energy changes between reaction intermediates have arouse an urgent call for exploring feasible calculation options toward generalized theoretical study. Here, a systematic mechanism study is provided toward ECO2RR via constrained ab initio molecular dynamics (cAIMD) simulations, in which the effects of solvent water molecules and temperature are taken into consideration to guide the synthesis of single‐atom alloy (SAA) catalyst. Consequently, the resultant Pr0.05/InBi achieves a maximum Faradic efficiency (FE) of 96.4% and an energy efficacy (EE) of 59.41% for formate. This work offers a novel approach to the design and screening of SAA catalysts, presenting foreseeable future in accelerating the industrial application process of ECO2RR.

CO Intermediate‐Assisted Dynamic Cu Sintering During Electrocatalytic CO2 Reduction on Cu−N−C Catalysts

AbstractThe 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.

[2+1] Cycloadditions Modulate the Hydrophobicity of Ni‐N4 Single‐Atom Catalysts for Efficient CO2 Electroreduction

Microenvironment regulation of M‐N4 single‐atom catalysts (SACs) is a promising way to tune their catalytic properties toward the electrochemical CO2 reduction reaction. However, strategies that can effectively introduce functional groups around the M‐N4 sites through strong covalent bonding and under mild reaction conditions are highly desired. Taking the hydrophilic Ni‐N4 SAC as a representative, we report herein a [2+1] cycloaddition reaction between Ni‐N4 and in‐situ generated difluorocarbene (F2C:), and enable the surface fluorocarbonation of Ni‐N4, resulting in the formation of a super‐hydrophobic Ni‐N4‐CF2 catalyst. Meanwhile, the mild reaction conditions allow Ni‐N4‐CF2 to inherit both the electronic and structural configuration of the Ni‐N4 sites from Ni‐N4. Enhanced electrochemical CO2‐to‐CO Faradaic efficiency above 98% is achieved in a wide operating potential window from −0.7 V to −1.3 V over Ni‐N4‐CF2. In‐situ spectroelectrochemical studies reveal that a highly hydrophobic microenvironment formed by the −CF2− group repels asymmetric H‐bonded water at the electrified interface, inhibiting the hydrogen evolution reaction and promoting CO production. This work highlights the advantages of [2+1] cycloaddition reactions on the covalent modification of N‐doped carbon‐supported catalysts.

[2+1] Cycloadditions Modulate the Hydrophobicity of Ni-N4 Single-Atom Catalysts for Efficient CO2 Electroreduction.

Microenvironment regulation of M-N4 single-atom catalysts (SACs) is a promising way to tune their catalytic properties toward the electrochemical CO2 reduction reaction. However, strategies that can effectively introduce functional groups around the M-N4 sites through strong covalent bonding and under mild reaction conditions are highly desired. Taking the hydrophilic Ni-N4 SAC as a representative, we report herein a [2+1] cycloaddition reaction between Ni-N4 and in-situ generated difluorocarbene (F2C:), and enable the surface fluorocarbonation of Ni-N4, resulting in the formation of a super-hydrophobic Ni-N4-CF2 catalyst. Meanwhile, the mild reaction conditions allow Ni-N4-CF2 to inherit both the electronic and structural configuration of the Ni-N4 sites from Ni-N4. Enhanced electrochemical CO2-to-CO Faradaic efficiency above 98% is achieved in a wide operating potential window from -0.7 V to -1.3 V over Ni-N4-CF2. In-situ spectroelectrochemical studies reveal that a highly hydrophobic microenvironment formed by the -CF2- group repels asymmetric H-bonded water at the electrified interface, inhibiting the hydrogen evolution reaction and promoting CO production. This work highlights the advantages of [2+1] cycloaddition reactions on the covalent modification of N-doped carbon-supported catalysts.

La-based Transition Metal Oxide Perovskites as Electrocatalysts for Electrochemical Carbon Dioxide Reduction

We report here the feasibility of using LaTMO3-based perovskites (TM = Co, Cr, Fe, Mn, Ni, i.e., non-Cu 3d transition metals) as electrocatalysts for electrochemical CO2 reduction reaction (eCO2RR). Phase pure LaTMO3 perovskites, having TM-ions in multiple oxidation states for all and O-defects for LaFeO3 and LaNiO3, have been synthesized and tested as electrocatalysts for eCO2RR in flow cell type set-up. The above characteristics of the La-TM-oxides have been found to influence the current densities during eCO2RR at the various applied potentials, with favorable effects of the presence of O-defects (as for LaFeO3 and LaNiO3). Upon eCO2RR, both C1 and C2 liquid products have been obtained, including ethanol, with a partial current density of −2.66 mA cm−2 at −1.2 V vs RHE (for LaFeO3). The types of products and the faradic efficiencies have been found to depend on the TM-ion present (in the LaTMO3); in particular, the oxidation state(s), associated O-defect(s) and electronic conductivity. Furthermore, the electrocatalysts have been found to be stable during eCO2RR. Overall, the present work highlights the potential of La-TM-oxide perovskites for usage as stable electrocatalysts for eCO2RR, and also provides insights into the proper selection of “TM” and reaction conditions for obtaining the desired product(s).

Tailoring the catalytic microenvironment of CuO with hydrophobic CuSA2 for selective CO2 electroreduction to C2+ products

Advancing the Faraday efficiency (FE) and current density of Cu catalyzed electrochemical CO2 reduction (ECR) reaction to produce C2+ products is important for its practical applications. Constructing a hydrophobic interface to regulate the local reaction environment is an effective method to improve the selectivity of C2+ products, but it is limited by the low reaction current density. In this work, we fabricated a novel hydrophobic and ECR active copper stearate (CuSA2) decorated CuO nanoparticle catalyst (CuO/CuSA2) for ECR reaction toward C2+ products. As a result, the CuO/CuSA2 catalyst achieved an FE of 61.33 % and a partial current density of 429.33 mA cm−2 for C2+ products. The CuSA2 and CuO nanoparticle cooperate very well for the formation of C2+ products. The in-situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) and electrochemical adsorption experiments indicated that the hydrophobic CuSA2 regulated the local ECR reaction environment. The local ∗CO2.- and *CO adsorption were strengthened by hydrophobic CuSA2 modification while the H2O adsorption was inhibited. CuO nanoparticle promotes *CO coupling reaction and enhances C2 intermediates (*OCCOH and *OC2H5) adsorption. Hydrophobic CuSA2 and CuO nanoparticle synergistically promote the generation of C2+ products. This work provides new insights into the design of hydrophobic CO2 reduction electrocatalysts for the preparation of C2+ products.

A Linear Correlation of p-Band Center with the Performance of Electrochemical CO2 Reduction Revealed by Sn Single-Atom Catalysts

The correlation between p-orbital energy level and catalytic activity of electrochemical CO2 reduction reaction (ECRR) is rarely reported, but significantly desired for further design of highly effective main group single-atom catalysts (SACs). Herein, a series of Sn-SACs (Sn-N3S1, Sn-N3P1, Sn-N3B1, and Sn-N4) were developed as a model system to explore structure-activity relationships of main group SACs for ECRR. Coordination environment regulation could upshift the p-band center of Sn, facilitating the adsorption of intermediates and improving the catalytic activity. Sn-N3S1 with the most positive p-band center shows a 100% Faradaic efficiency of CO (FECO), superior over that of Sn-N4 and other reported SACs. Notably, the catalytic performance of Sn-SACs shows a linear relationship with p-band center of Sn, indicating a high applicability of p-band center as a descriptor for catalytic performance. This work provides a new way to boost ECRR by lowering the p-orbital energy level of main group metal.

Anchored silver-palladium aerogel on carbon cloth via diazonium chemistry for electrochemical reduction of CO2

Electrochemical CO2 reduction reaction (eCO2RR) is a promising route for removal of CO2 from the atmosphere and transforming it into value-added products. The development of new and efficient catalysts plays a vital role in this regard. Here a combination of carbon grafting and bimetallic metal aerogel is presented as a catalyst for eCO2RR. The grafted surface plays an essential function in assembling the catalyst on the carbon cloth (CC) surface as a supported catalyst. Herein, we describe the use of para-aminothiophenol (p-TP) as a grafting agent combined with diazonium chemistry to fix a metallic aerogel catalyst on CC as support. The silver, palladium and bi-metallic silver-palladium aerogels (Ag-p-TP, Pd-p-TP, and AgPd-p-TP) anchored onto the surface of CC yielding the corresponding surface-bound materials were used for testing the electrochemical reduction of CO2. The mono-metallic Ag carbon cloth (Ag-p-TP/CC) exhibited the ability in reducing CO2 to CO with moderate Faradaic efficiency (FE) of 74 % in 0.1 M, NaHCO3 electrolyte at pH = 7.5. The bimetallic AgPd-p-TP-CC further enhanced the Faradaic efficiency for CO formation to 88.7 %, with an unexpectedly low onset potential of −0.09 V vs. RHE. Surprisingly, formate was identified to be the liquid product when Pd-p-TP-CC and AgPd-p-TP-CC were used, with maximal FEformate of 19.0 % and 25.7 % at −1.0 V vs. RHE, respectively. In contrast, CC lacking the chemical grafting that allows immobilization of the metal aerogel (Ag-Pd/CC) exhibits lower FEco% for eCO2RR, highlighting the importance of this chemical modification of the carbon cloth surface. Diazonium chemistry coupled with metal aerogels is a new approach to generating surface-bound catalysts for the effective reduction of CO2.

Lattice-dislocated bismuth nanowires formed by in-situ chemical etching on copper foam for enhanced electrocatalytic CO2 reduction

Electrochemical CO2 reduction reaction (CO2RR) to HCOOH is one of the most feasible and economical methods to achieve carbon neutrality. Bismuth (Bi), as a metal catalyst for CO2RR, is considered to have great potential for application and has been widely studied due to its high formate selectivity, low toxicity, cheapness, and abundance. Unfortunately, low current density and short electrode lifetime have hindered its progress towards practical applications. In this work, we present a method that enables the chemical etching of Bi on Cu, which is capable of spontaneously accomplishing the loading of Bi on Cu foam in the liquid phase at room temperature. Additionally, to provide more abundant catalytically active sites, twisted Bi nanowires (BiNWs) with lattice dislocations were successfully prepared on the surface of Cu foam using a three-step chemical method involving oxidation, reduction, and in-situ etching. The Cu Foam@BiNWs was found to be a highly active electrocatalyst for CO2 reduction to formate at a low applied potential, achieving a faradaic efficiency for formate (FEFormate) of 95 % and a formate partial current density of ∼ 12 mA cm−2 at −0.78 V vs. RHE (reversible hydrogen electrode). Even within such a wide potential window of −0.68 ∼ -1.08 V vs. RHE, the FEFormate is consistently above 90 %. Such exceptional CO2 reduction activity can be attributed to the distortions and lattice dislocations present in the surface BiNWs. Furthermore, the Cu Foam@BiNWs electrode demonstrated a total current density close to 100 mA cm−2 at −0.98 V in an alkaline flow cell, while maintaining excellent catalytic stability over a prolonged 30-hour period of high current density electrochemical activity, thus showing potential for advancing the industrialisation of formate production. This work emphasizes the crucial role of size-dependent catalysis and crystal defect engineering strategies in the field of electrocatalysis, elucidates the mechanism of the rate-determining step (RDS) in the electrocatalytic CO2 reduction process on the developed catalysts, which can provide valuable insights into the design and development of high performance electrocatalysts not only in CO2RR but also in other fields.

Phase transfer-assisted indium recovery from spent liquid crystal display panels and its extension in preparing indium-based electrocatalysts for CO2 reduction

Transforming discarded electronic devices into low-cost and high-efficiency catalysts presents a win–win approach to address the scarcity of rare resources and sustainable energy challenges. Herein, we report an effective strategy that combines an ethanol-mediated dodecylamine (DDA) phase transfer with hydrothermal methods for facilitating the facile synthesis of indium (In)-based nanomaterials from the leachates of liquid crystal display panels (LCDPs) toward high-efficiency electrochemical CO2 reduction reaction (eCO2RR). In this strategy, the rapid formation of coordinating compounds between the –NH2 group of DDA and metal ions facilitates the separation of In3+ cations from the acidic LCDPs leach solution by transferring them into an organic phase, which are then converted into InOOH nanoparticles with abundant oxygen vacancies (denoted as In-LCDPs and hereafter) through a low-temperature hydrothermal process. The eCO2RR evaluations confirm the superior electrocatalytic performance of the In-based nanoparticles produced from the LCDPs. In specific, within a broad potential range (−0.77 to −1.17 V vs RHE), the In-LCDPs show a Faradaic efficiency for formate (FEformate) of 85 %, with the highest FEformate of 90.23 % at −0.97 V vs RHE, which is comparable to the FEformate (93.8 % at −0.97 V vs RHE) of In-based catalyst prepared from pure In precursors using the same method. Further investigations reveal that the Sn and Al impurities have minimal impact on the catalytic performance of In-LCDPs, while the presence of Fe3+ impurities significantly enhance the production of hydrogen during the eCO2RR. This work might have provided a scalable pathway to transform LCDPs into value-added electrocatalysts for eCO2RR.

Enhanced Electrochemical CO2 Reduction to Formate over Phosphate-Modified In: Water Activation and Active Site Tuning.

Electrochemical CO2 reduction reaction (CO2RR) offers a sustainable strategy for producing fuels and chemicals. However, it suffers from sluggish CO2 activation and slow water dissociation. In this work, we construct a (P-O)δ- modified In catalyst that exhibits high activity and selectivity in electrochemical CO2 reduction to formate. A combination of in-situ characterizations and kinetic analyses indicate that (P-O)δ- has a strong interaction with K+(H2O)n, which effectively accelerates water dissociation to provide protons. In-situ attenuated total reflectance surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) measurements together with density functional theory (DFT) calculations disclose that (P-O)δ- modification leads to a higher valence state of In active site, thus promoting CO2 activation and HCOO* formation, while inhibiting competitive hydrogen evolution reaction (HER). As a result, the (P-O)δ- modified oxide-derived In catalyst exhibits excellent formate selectivity across a broad potential window with a formate Faradaic efficiency as high as 92.1% at a partial current density of ~200 mA cm-2 and a cathodic potential of -1.2 V vs. RHE in an alkaline electrolyte.

Enhanced Electrochemical CO2 Reduction to Formate over Phosphate‐Modified In: Water Activation and Active Site Tuning

Electrochemical CO2 reduction reaction (CO2RR) offers a sustainable strategy for producing fuels and chemicals. However, it suffers from sluggish CO2 activation and slow water dissociation. In this work, we construct a (P‐O)δ− modified In catalyst that exhibits high activity and selectivity in electrochemical CO2 reduction to formate. A combination of in‐situ characterizations and kinetic analyses indicate that (P‐O)δ− has a strong interaction with K+(H2O)n, which effectively accelerates water dissociation to provide protons. In‐situ attenuated total reflectance surface‐enhanced infrared absorption spectroscopy (ATR‐SEIRAS) measurements together with density functional theory (DFT) calculations disclose that (P‐O)δ− modification leads to a higher valence state of In active site, thus promoting CO2 activation and HCOO* formation, while inhibiting competitive hydrogen evolution reaction (HER). As a result, the (P‐O)δ− modified oxide‐derived In catalyst exhibits excellent formate selectivity across a broad potential window with a formate Faradaic efficiency as high as 92.1% at a partial current density of ~200 mA cm−2 and a cathodic potential of ‐1.2 V vs. RHE in an alkaline electrolyte.

Local CO2 reservoir layer promotes rapid and selective electrochemical CO2 reduction

Electrochemical CO2 reduction reaction in aqueous electrolytes is a promising route to produce added-value chemicals and decrease carbon emissions. However, even in Gas-Diffusion Electrode devices, low aqueous CO2 solubility limits catalysis rate and selectivity. Here, we demonstrate that when assembled over a heterogeneous electrocatalyst, a film of nitrile-modified Metal-Organic Framework (MOF) acts as a remarkable CO2-solvation layer that increases its local concentration by ~27-fold compared to bulk electrolyte, reaching 0.82 M. When mounted on a Bi catalyst in a Gas Diffusion Electrode, the MOF drastically improves CO2-to-HCOOH conversion, reaching above 90% selectivity and partial HCOOH currents of 166 mA/cm2 (at −0.9 V vs RHE). The MOF also facilitates catalysis through stabilization of reaction intermediates, as identified by operando infrared spectroscopy and Density Functional Theory. Hence, the presented strategy provides new molecular means to enhance heterogeneous electrochemical CO2 reduction reaction, leading it closer to the requirements for practical implementation.

Dynamic (Sub)surface-Oxygen Enables Highly Efficient Carbonyl-Coupling for Electrochemical Carbon Dioxide Reduction.

Nowadays high-valent Cu species (i.e., Cuδ+) has been clarified to enhance multi-carbon production in electrochemical CO2 reduction reaction (CO2RR). Nonetheless, the inconsistent average Cu valence states have been reported to significantly govern the product profile of CO2RR, which may lead to misunderstanding of the enhanced mechanism for multi-carbon production and results in an ambiguous roles of high-valent Cu species. Dynamic Cuδ+ during CO2RR leads to erratic valence states and challenges of high-valent species determination. Herein, we propose an alternative descriptor of (sub)surface oxygen, the (sub)surface-oxygenated degree (κ) to quantify the active high-valent Cu species on the (sub)surface, which regulates the multi-carbon production of CO2RR. The κ validates a strong correlation to the carbonyl (*CO) coupling efficiency and is the critical factor for the multi-carbon enhancement, in which an optimized Cu2O@Pd2.31 achieves the multi-carbon partial current density of ∼330 mA cm-2 with a faradaic efficiency of 83.5%. This work shows a promising way to unveil the role of high-valent species and further achieve carbon neutralization. This article is protected by copyright. All rights reserved.

Gray mesoporous SnO2 catalyst for CO2 electroreduction with high partial current density and formate selectivity

The mesoporous metal oxide semiconductors exhibit unique chemical and physical characteristics, making them highly desirable for catalysis, electrochemistry, energy conversion, and energy storage applications. Here, we report the facial fabrication of mesoporous gray SnO2 (MGS) electrocatalysts employing an evaporation-induced co-assembly (EICA) approach, utilizing poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) triblock copolymers Pluronic P123 (PEO-PPO-PEO) triblock copolymer as a template for electrochemical CO2 reduction reaction (eCO2RR). By sustaining the co-assembly conditions and utilizing a thermal treatment technique based on carbon, gray mesoporous SnO2 materials with a high density of active sites and oxygen vacancies can be constructed. The MGS materials were employed in eCO2RR in a flow cell type, which exhibits excellent catalytic activity and selectivity toward formate with a high partial current density of -234 mA cm-2 and Faradic efficiency (FE) of 93.60 % at -1.3 V vs. reversible hydrogen electrode (RHE). Interestingly, the mesoporous SnO2 with a 1.5 wt% ratio of Sn precursor to P123 surfactant (MS-1.5@350N-400A) electrode exhibits a high level of Faradaic efficiency (FE) of (98%) at a low overpotential of -0.6 VRHE, which is a seldom recorded performance for similar systems. A stable FE of 96 ± 1% was observed in the range of -0.6 to -1.2 VRHE, which is the result of a large surface area (184 m2 /g) and a high number of active sites and oxygen vacancies within the mesostructured framework.

Anionic Coordination Control in Building Cu-Based Electrocatalytic Materials for CO2 Reduction Reaction.

Renewable energy-driven conversion of CO2 to value-added fuels and chemicals via electrochemical CO2 reduction reaction (CO2RR) technology is regarded as a promising strategy with substantial environmental and economic benefits to achieve carbon neutrality. Because of its sluggish kinetics and complex reaction paths, developing robust catalytic materials with exceptional selectivity to the targeted products is one of the core issues, especially for extensively concerned Cu-based materials. Manipulating Cu species by anionic coordination is identified as an effective way to improve electrocatalytic performance, in terms of modulating active sites and regulating structural reconstruction. This review elaborates on recent discoveries and progress of Cu-based CO2RR catalytic materials enhanced by anionic coordination control, regarding reaction paths, functional mechanisms, and roles of different non-metallic anions in catalysis. Finally, the review concludes with some personal insights and provides challenges and perspectives on the utilization of this strategy to build desirable electrocatalysts.