Constraint of Reaction Intermediates in Ag@Cu2O Porous Core-Shell Nanospheres Toward Boosted CO2 Electroreduction to C2H4.

Efficient Electrocatalytic CO2 Reduction to C2+ Alcohols at Defect-Site-Rich Cu Surface

Electroreduction of CO2 to target products with high activity and selectivity has techno-economic importance for renewable energy storage and CO2 utilization. Herein, we report a hierarchical CuS h...

Three-dimension porous Zn-Cu alloy: An inexpensive electrocatalyst for highly selective CO2 reduction to CO in non-aqueous electrolyte

Tandem effect at snowflake-like cuprous sulphide interfaces for highly selective conversion of carbon dioxide to formate by electrochemical reduction

Electrochemical CO2 reduction has garnered significant interest in the conversion of sustainable energy to valuable fuels and chemicals. Cu-based bimetallic catalysts play a crucial role in enhancing *CO concentration on Cu sites for efficient C─C coupling reactions, particularly for C2 product generation. To enhance Cu's electronic structure and direct its selectivity toward C2 products, a novel strategy is proposed involving the in situ electropolymerization of a nano-thickness cobalt porphyrin polymeric network (EP-CoP) onto a copper electrode, resulting in the creation of a highly effective EP-CoP/Cu tandem catalyst. The even distribution of EP-CoP facilitates the initial reduction of CO2 to *CO intermediates, which then transition to Cu sites for efficient C─C coupling. DFT calculations confirm that the *CO enrichment from Co sites boosts *CO coverage on Cu sites, promoting C─C coupling for C2+ product formation. The EP-CoP/Cu gas diffusion electrode achieves an impressive current density of 726mAcm-2 at -0.9V versus reversible hydrogen electrode (RHE), with a 76.8% Faraday efficiency for total C2+ conversion and 43% for ethylene, demonstrating exceptional long-term stability in flow cells. These findings mark a significant step forward in developing a tandem catalyst system for the effective electrochemical production of ethylene.

The technology of CO2 electrochemical reduction (CO2ER) provides a means to convert CO2, a waste greenhouse gas, into value-added chemicals. Copper is the most studied element that is capable of catalyzing CO2ER to obtain multicarbon products, such as ethylene, ethanol, acetate, etc., at an appreciable rate. Under the operating condition of CO2ER, the catalytic performance of Cu decays because of several factors that alters the surface properties of Cu. In this review, these factors that cause the degradation of Cu-based CO2ER catalysts are categorized into generalized deactivation modes, that are applicable to all electrocatalytic systems. The fundamental principles of each deactivation mode and the associated effects of each on Cu-based catalysts are discussed in detail. Structure- and composition-activity relationship developed from recent in situ/operando characterization studies are presented as evidence of related deactivation modes in operation. With the aim to address these deactivation modes, catalyst design and reaction environment engineering rationales are suggested. Finally, perspectives and remarks built upon the recent advances in CO2ER are provided in attempts to improve the durability of CO2ER catalysts.

Toward abiotic sugar synthesis from CO2 electrolysis

Polyacrylate modified Cu electrode for selective electrochemical CO2 reduction towards multicarbon products

Mechanistic study of the CO oxidation reaction on the CuO (111) surface during chemical looping combustion

Intermediate enrichment effect of porous Cu catalyst for CO2 electroreduction to C2 fuels

Formic acid is receiving intensive attention as being one of the most progressive chemical fuels for the electrochemical reduction of carbon dioxide. However, the majority of catalysts suffer from low current density and Faraday efficiency. To this end, an efficient catalyst of In/Bi-750 with InOx nanodots load is prepared on a two-dimensional nanoflake Bi2 O2 CO3 substrate, which increases the adsorption of * CO2 due to the synergistic interaction between the bimetals and the exposure of sufficient active sites. In the H-type electrolytic cell, the formate Faraday efficiency (FE)reaches 97.17% at -1.0V (vs reversible hydrogen electrode (RHE)) with no significant decay over 48 h. A formate Faraday efficiency of 90.83% is also obtained in the flow cell at a higher current density of 200mA cm-2 . Both in-situ Fourier transform infrared spectroscopy (FT-IR) and theoretical calculations show that the BiIn bimetallic site can deliver superior binding energy to the * OCHO intermediate, thereby fundamentally accelerating the conversion of CO2 to HCOOH. Furthermore, assembled Zn-CO2 cell exhibits a maximum power of 6.97mW cm-1 and a stability of 60 h.

Electrocatalytic CO ₂ Reduction over Bimetallic Bi-Based Catalysts: A Review

Nanoconfinement and tandem catalysis over yolk-shell catalysts towards electrochemical reduction of CO2 to multi-carbon products.

The technique of electrocatalytic CO2 reduction (ECR) is emerging as a competent candidate for neutralizing the excessive anthropogenic carbon emission, and for producing a multitude of value-added chemicals. In particular, ECR is well compatible with renewable electricity-generating technologies, and can help to alleviate their innate issue of intermittency and to level the energy output of power grid. Yet ECR itself typically suffers from the chemical inertness and low solubility of CO2, multiple products and low selectivity, and the undesired parasitic hydrogen evolution reaction in aqueous electrolytes. Therefore, electrocatalysts featuring low overpotentials, high current densities, high Faradaic efficiencies and high stabilities are in constant pursuit. From the viewpoint of Faradaic efficiency and current density that have been achieved thus far, the most promising products are CO and formic acid (among C1 products), and ethylene and ethanol (among C2 products). Different from C1 products, C2 products are formed via carbon-carbon coupling (C–C coupling) following a second-order reaction kinetics, generally with more complicated reaction mechanisms involving multiple electron transfer and therefore more stringent requirements on the electrocatalysts. As such, at the center of synthesizing C2 products via ECR is the in-depth understanding on reaction mechanisms and the rational design of advanced electrocatalysts. Up to date, the ECR catalysts that can yield C2 products are primarily based on Cu-related materials, and CO has been recognized as the most important and versatile intermediate for C–C coupling. This review summarizes the reports on the relevant underlying reaction mechanisms, and elaborates on the three most widely accepted catalytic mechanisms for C–C coupling on Cu-based catalysts: CO dimerization, CO+CHO coupling, and CH2 carbene dimerization. These mechanisms proposed on the basis of theoretical calculation, take effect in different regimes of applied electric potential, and have also found substantial support from experimental data obtained particularly via in situ and operando spectroscopies. The rational design of Cu-based catalysts can effectively improve the reaction selectivity for C–C coupling. In this regard, this review discusses Cu-based catalysts in different subcategories: bulk Cu catalysts, Cu nanocatalysts, oxide-derived Cu catalysts, and Cu-based bimetallic catalysts, and put major emphasis on the effects of exposed facet, particle size, shape, loading density, oxidation state of surface atoms and alloying on steering the selectivity towards C–C coupling pathways. It has been found that Cu-based catalysts that feature (100) facets, regular shapes, high loading areal densities and partially oxidized Cu atoms generally give superior performances in yielding C2 and C2+ products, because their optimized surface and electronic structures can effectively elevate the local concentration of CO intermediates or lower the activation barrier for C–C coupling. A few topics other than Cu-based catalysts are also briefly discussed at the end of this review. We stress the irreplaceable importance of in situ and operando characterization techniques in probing and deciphering the catalytic mechanism of ECR, the design and optimization of electrolytes and electrodes in help to alter the selectivity for different products, and most importantly, a range of novel catalysts that have emerged in recent years, including tandem catalysts, single-atomic catalysts, non-Cu-based metal catalysts, non-metal catalysts based on graphene and nanodiamond, as well as molecular catalysts, which have witnessed a resurgence after the proposal of the idea of heterogeneous immobilization.

The preparation of ethylene (C2H4) by electrochemical CO2 reduction (ECO2R) has dramatically progressed in recent years. However, the slow kinetics of carbon-carbon (C-C) coupling remains a significant challenge. A generalized facet reconstruction strategy is reported to prepare a 3-phase mixed pre-catalyst (Cu3N-300) of Cu3N, Cu2O, and CuO by controlling the calcination temperature and to obtain the derived Cu catalyst (A-Cu3N-300-0.5) enriched with Cu(111)/Cu(200) grain boundaries (GBs) by subsequent constant potential reduction. Its Faraday efficiency (FE) toward C2H4 at a low reaction potential of -1.07V (vs reversible hydrogen electrode (RHE)) is 46.03%, which is much higher than the other 3 derived Cu catalysts containing single Cu(111) facets (24.89% and 24.52%) and Cu(111)/Cu(111) GBs (28.66%). Combining in situ experimental and theoretical computational studies, abundant Cu(111)/Cu(200) GBs is found to enhance CO2 activation and significantly promote the formation and adsorption of *CO intermediates, thereby lowering the activation energy barrier of C-C coupling and increasing the FE of C2H4.