Electrochemical CO2 Research Articles

The Electrode/Electrolyte Interface Study during the Electrochemical CO2 Reduction in Acidic Electrolytes

AbstractElectrochemical CO2 Reduction (CO2R) in acidic electrolytes has gained significant attention owing to higher carbon efficiency and stability than in alkaline counterparts. However, the proton source and the role of alkali cations for CO2R are still under debate. By using rotating ring disk electrode and surface‐enhanced infrared absorption spectroscopy, we find that a neutral/alkaline environment at the interface is necessary for CO2R even in acidic electrolytes. We also confirm that water molecules, rather than protons serve as the proton source for CO2R. Alkali cations in the outer Helmholtz plane activate H2O and promote the desorption of adsorbed carbon monoxide. Additionally, the solvated CO2, or CO2(aq), is the actual reactant for CO2R. This study provides a deeper understanding of the electrode/electrolyte interface during CO2R in acidic electrolytes and sheds light on further performance improvement of this system.

Controlling the Polarity of Metal–Organic Frameworks to Promote Electrochemical CO2 Reduction

AbstractThe addition of polar functional groups to porous structures is an effective strategy for increasing the ability of metal–organic frameworks (MOFs) to capture CO2 by enhancing interactions between the dipoles of the polar functional groups and the quadrupoles of CO2. However, the potential of MOFs with polar functional groups to activate CO2 has not been investigated in the context of CO2 electrolysis. In this study, we report a mixed‐ligand strategy to incorporate various functional groups in the MOFs. We found that substituents with strong polarity led to increased catalytic performance of electrochemical CO2 reduction for these polarized MOFs. Both experimental and theoretical evidence indicates that the presence of polar functional groups induces a charge redistribution in the micropores of MOFs. We have shown that higher electron densities of sp2‐carbon atoms in benzimidazolate ligands reduces the energy barrier to generate *COOH, which is simultaneously controlled by the mass transfer of CO2. Our research offers an effective method of disrupting local electron neutrality in the pores of electrocatalysts/supports to activate CO2 under electrochemical conditions.

Comparative Study of Different Polymeric Binders in Electrochemical CO Reduction

Comparative Study of Different Polymeric Binders in Electrochemical CO Reduction

Insights into Energetic Penalties in Electrochemical CO2 Separation Systems

Insights into Energetic Penalties in Electrochemical CO₂ Separation Systems

Gapped and Rotated Grain Boundary Revealed in Ultra‐Small Au Nanoparticles for Enhancing Electrochemical CO2 Reduction

AbstractAlthough gapped grain boundaries have often been observed in bulk and nanosized materials, and their crucial roles in some physical and chemical processes have been confirmed, their acquisition at ultrasmall nanoscale presents a significant challenge. To date, they had not been reported in metal nanoparticles smaller than 2 nm owing to the difficulty in characterization and the high instability of grain boundary (GB) atoms. Herein, we have successfully developed a synthesis method for producing a novel chiral nanocluster Au78(TBBT)40 (TBBT=4‐tert‐butylphenylthiolate) with a 26‐atom gapped and rotated GB. This nanocluster was precisely characterized using single‐crystal X‐ray crystallography and mass spectrometry. Additionally, an offset atomic defect linked to the peripheral Au(TBBT)2 staple was found in the structure. Comparing it to similarly face‐centered cubic‐structured Au36(TBBT)24, Au44(TBBT)28, Au52(TBBT)32, Au92(TBBT)44, and ~5 nm nanocrystals, the bridging Au78(TBBT)40 nanocluster exhibited higher catalytic activity in the electroreduction of CO2 to CO. This enhanced activity was explained through density functional theory calculations and X‐ray photoelectron spectroscopy analysis, which highlight the impact of GBs and point defects on the surface properties of metal nanoclusters in balancing intermediate adsorption and product desorption.

Quantifying Interface‐Performance Relationships in Electrochemical CO2 Reduction through Mixed‐Dimensional Assembly of Nanocrystal‐on‐Nanowire Superstructures

AbstractFine‐tuning the interfacial sites within heterogeneous catalysts is pivotal for unravelling the intricate structure–property relationship and optimizing their catalytic performance. Herein, a simple and versatile mixed‐dimensional assembly approach is proposed to create nanocrystal‐on‐nanowire superstructures with precisely adjustable numbers of biphasic interfaces. This method leverages an efficient self‐assembly process in which colloidal nanocrystals spontaneously organize onto Ag nanowires, driven by the solvophobic effect. Importantly, varying the ratio of the two components during assembly allows for accurate control over both the quantity and contact perimeter of biphasic interfaces. As a proof‐of‐concept demonstration, a series of Au‐on‐Ag superstructures with varying numbers of Au/Ag interfaces are constructed and employed as electrocatalysts for electrochemical CO2‐to‐CO conversion. Experimental results reveal a logarithmic linear relationship between catalytic activity and the number of Au/Ag interfaces per unit mass of Au‐on‐Ag superstructures. This work presents a straightforward approach for precise interface engineering, paving the way for systematic exploration of interface‐dependent catalytic behaviors in heterogeneous catalysts.

In Situ Transformation of Hybrid Bismuth Halide into Rhombohedral Bismuth for Electrochemical CO2 Reduction to Formate

AbstractBi‐based electrocatalysts have attracted high attention due to their high selectivity for formate, low cost, and high biocompatibility. Surface modification with halides can adjust the surface charge distribution of metal catalysts, thereby regulating the binding force of the intermediate. Organic‐inorganic hybrid bismuth halides provide an alternative, especially low dimensional structures. Herein, zero‐dimensional hybrid bismuth halides containing Bi4I16 units (denoted as Bi4I16) was recommended as pre‐catalyst due to the Bi ⋅ ⋅ ⋅ Bi spacing in Bi4I16 is 4.760 Å, nearly equaling to the Bi ⋅ ⋅ ⋅ Bi spacing in rhombohedral Bi (4.750 Å). The equal spacing may be more beneficial for the electricity‐driven in situ conversion and rearrangement of Bi atoms in the catalytic process. As a contrast, zero‐dimensional bismuth halide containing Bi2I9 units (denoted as Bi2I9) with shorter Bi ⋅ ⋅ ⋅ Bi spacing (4.2415 Å) was prepared. The working electrode prepared by Bi4I16 ink was measured for CO2RR, and the partial formate current density can reach 8.2 mA cm−2 at −1.1 V vs RHE. The Bi4I16 catalyst delivers a maximum Faradaic Efficiency (FE, ~80 %) for formate at −0.86 V vs RHE and maintain a FE higher than 78.5 % after 16 h.

A Regenerable Bi‐Based Catalyst for Efficient and Stable Electrochemical CO2 Reduction to Formate at Industrial Current Densities

AbstractRenewable electricity shows immense potential as a driving force for the carbon dioxide reduction reaction (CO2RR) in production of formate (HCOO−) at industrial current density, providing a promising path for value‐added chemicals and chemical manufacturing. However, achieving high selectivity and stable production of HCOO− at industrial current density remains a challenge. Here, we present a robust Bi0.6Cu0.4 NSs catalyst capable of regenerating necessary catalytic core (Bi−O) through cyclic voltammetry (CV) treatment. Notably, at 260 mA cm−2, faradaic efficiency of HCOO− reaches an exceptional selectivity to 99.23 %, maintaining above 90 % even after 400 h, which is longest reaction time reported at the industrial current density. Furthermore, in stability test, the catalyst was constructed by CV reconstruction to achieve stable and efficient production of HCOO−. In 20 h reaction test, the catalyst has a rate of HCOO− production of 13.24 mmol m−2 s−1, a HCOO− concentration of 1.91 mol L−1, and an energy consumption of 129.80 kWh kmol−1. In situ Raman spectroscopy reveals the formation of Bi−O structure during the gradual transformation of catalyst from Bi0.6Cu0.4 NBs to Bi0.6Cu0.4 NSs. Theoretical studies highlight the pivotal role of Bi−O structure in modifying the adsorption behavior of reaction intermediates, which further reduces energy barrier for *OCHO conversion in CO2RR.

Microwave-Assisted Synthesis of a Defect-Rich CuO Electrode for Selective Electrochemical CO2 Reduction to C2+ Products

Microwave-Assisted Synthesis of a Defect-Rich CuO Electrode for Selective Electrochemical CO₂ Reduction to C₂₊ Products

Sol–Gel Synthesis of CuO Nanoparticles and Its Use as Catalyst for Electrochemical CO2 Reduction

Sol–Gel Synthesis of CuO Nanoparticles and Its Use as Catalyst for Electrochemical CO₂ Reduction

Atomically Isolated Pd Sites Promote Electrochemical CO Reduction to Acetate through a Protonation-Regulated Mechanism.

Electrochemical CO reduction reaction (CORR) offers a promising approach for sustainable acetate production, the promotion of which requires the control of multiple protonation steps. This paper describes the synthesis of atomically isolated Pd sites onto Cu nanoflakes to regulate the protonation of key intermediates. The Pd sites with moderate water activation capability are found to enhance the protonation of *CO at the neighboring Cu site to *COH, which is confirmed to be the rate-determining step through kinetic isotope effect studies. The formation of *COH-*CO is therefore promoted. Additionally, the Pd sites would preferentially protonate the C-OH group in *COH-*CO due to the spatial approximability and electronic modulation effects, generating *CCO for the selective formation of acetate. An acetate Faradaic efficiency of 59.5% is achieved at -0.78 V vs reversible hydrogen electrode (RHE), with a maximum partial current density of 286 mA cm-2 at -0.86 V vs RHE. The optimized catalyst also exhibits long-term stability for 500 h at 100 mA cm-2 in a membrane electrode assembly. This work reveals a new promoting mechanism for selective CORR with simultaneous tuning of the structural and electronic properties of the proton-supplying sites.

Cation effect on the elementary steps of the electrochemical CO reduction reaction on Cu

Cation effect on the elementary steps of the electrochemical CO reduction reaction on Cu

Correction to “Origin of Metal-Support Interactions for Selective Electrochemical CO2 Reduction into C1 and C2+ Products”

Correction to “Origin of Metal-Support Interactions for Selective Electrochemical CO₂ Reduction into C₁ and C₂₊ Products”

Electrochemical CO2 Reduction in Deep Eutectic Solvent: Effect of Water and Organic Diluents

Electrochemical CO₂ Reduction in Deep Eutectic Solvent: Effect of Water and Organic Diluents

Facile Synthesis of Porous Zinc Nanosheets for Highly Selective Electrochemical CO2 Reduction to CO

AbstractWith the increasing levels of CO2 emissions and the decreasing availability of energy resources, the electrocatalytic CO2 reduction reaction (CO2RR) offers a promising method for utilizing CO2 as a valuable resource using sustainable electrical energy. However, developing cost‐effective and highly efficient catalysts remains a significant challenge. Although zinc, an abundant element on Earth, has shown potential for converting CO2 into CO, its effectiveness as a catalyst for CO2 reduction is hindered by its low selectivity and stability. This study introduces a fast, efficient, and simple electrochemical deposition method for preparing porous zinc nanosheets (NS) using the hydrogen bubble template approach. The as‐prepared zinc NS catalyst demonstrates exceptional catalytic activity due to its highly porous structure and high specific surface area. At a voltage of −1 V versus RHE, it achieves a maximum CO Faradaic efficiency of 89.5 %. The performance of this system is characterized by a partial current density of around −6.17 mA cm−2 in an H‐cell configuration. Additionally, our catalyst exhibits remarkable durability over 10 h, highlighting its significant potential for real‐world utilization in CO2RR.

Oxygen Vacancy-Induced and Boundary Effects Promote Electrochemical CO2 Reduction to Formic Acid under Acid Electrolytes

Oxygen Vacancy-Induced and Boundary Effects Promote Electrochemical CO₂ Reduction to Formic Acid under Acid Electrolytes

Effective Screening Descriptors of Metal–Organic Framework-Supported Single-Atom Catalysts for Electrochemical CO2 Reduction Reactions: A Computational Study

Effective Screening Descriptors of Metal–Organic Framework-Supported Single-Atom Catalysts for Electrochemical CO₂ Reduction Reactions: A Computational Study

Electrochemical CO2 Reduction by Cobalt(II)2,9,16,23-tetra(amino)phthalocyanine: Enhancement Effect of Active Sites toward Methanol Formation

Electrochemical CO₂ Reduction by Cobalt(II)2,9,16,23-tetra(amino)phthalocyanine: Enhancement Effect of Active Sites toward Methanol Formation

Theoretical Investigation of the Adsorbate and Potential-Induced Stability of Cu Facets during Electrochemical CO2 and CO Reduction

The activity and product selectivity of electrocatalysts for reactions like the carbon dioxide and carbon monoxide reduction reactions (CO2RR and CORR) are intimately dependent on the catalyst’s structure and composition. While engineering catalytic surfaces can improve performance, discovering the key sets of rational design principles remains challenging due to limitations in modeling catalyst stability under operating conditions. Herein, we perform first-principles density functional calculations adopting implicit solvation methods with potential control to study the influence of adsorbates and applied potential on the stability of different facets of model Cu electrocatalysts. Using coverage dependencies extracted from microkinetic models, we describe an approach for calculating potential and adsorbate-dependent contributions to surface energies under reaction conditions, where Wulff constructions are used to understand the morphological evolution of Cu electrocatalysts under CO2RR and CORR conditions. We identify that CO*, a key reaction intermediate, exhibits higher kinetically and thermodynamically accessible coverages on (100) relative to (111) facets, which can translate into an increased relative stabilization of the (100) facet during CO2RR. Our results support the known tendency for increased (111) faceting of Cu nanoparticles under more reducing conditions and that the relative increase in (100) faceting observed under CO2RR conditions is likely attributed to differences in CO* coverage between these facets.This work was partially performed under the auspices of the U.S. DOE by Lawrence Livermore National Laboratory under contract DE-AC52-07NA27344 and partially supported by the U.S. DOE, Office of Energy Efficiency and Renewable Energy, Advanced Materials & Manufacturing Office.

Dimensionality Engineering toward Carbon Materials for Electrochemical CO2 Reduction: Progress and Prospect

AbstractCarbon materials are of great significance in state‐of‐the‐art electrochemical CO2 reduction (ECR) as key components such as electrocatalysts, gas diffusion electrodes, and current collectors. Notably, dimensionalities of carbons and related manipulations play vital roles in boosting ECR performance, e.g., mass/charge transfer dynamics, exposure of active sites, reaction space, product's Faradaic efficiency/selectivity, and durability. Here, recent endeavors in dimensionality engineering toward advanced carbon‐based materials for ECR is first summarized, including pure carbons (e.g., carbon nanotube and graphene) and carbon composites, and highlight the dimensionality‐dependent properties toward ECR performance. Various engineering strategies referring to dimensionality modulation and integration have been summarized, e.g., top‐down, bottom‐up, and soft chemical approaches. Design principles of dimensionality‐varied carbons are elaborated, the impacts of dimensionalities of carbons and related surface chemistry (e.g., functional group, wettability, and electronic structure) on ECR kinetics and product‐targeted mechanisms are also scrutinized. Some insights into how the dimensionality manipulation of carbons elevates performance of carbon‐based materials in mass/charge transfer acceleration, ECR kinetics, and product selectivity are provided. At last, a perspective for challenges and future development of dimensionality‐varied carbon materials is discussed. This review aims at providing guidance for customizable construction of carbon materials with dimensionality dependence toward green and energy‐saving electrosynthesis systems.