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Chemicals manufacturing consumes large amounts of energy and is responsible for a substantial portion of global carbon emissions. Electrochemical systems that produce the desired compounds by using renewable electricity offer a route to lower carbon emissions in the chemicals sector. Ethylene oxide is among the world’s most abundantly produced commodity chemicals because of its importance in the plastics industry, notably for manufacturing polyesters and polyethylene terephthalates. We applied an extended heterogeneous:homogeneous interface, using chloride as a redox mediator at the anode, to facilitate the selective partial oxidation of ethylene to ethylene oxide. We achieved current densities of 1 ampere per square centimeter, Faradaic efficiencies of ~70%, and product specificities of ~97%. When run at 300 milliamperes per square centimeter for 100 hours, the system maintained a 71(±1)% Faradaic efficiency throughout.

Producing liquid fuels such as ethanol from CO 2 , H 2 O, and renewable electricity offers a route to store sustainable energy. The search for efficient electrocatalysts for the CO 2 reduction reaction relies on tuning the adsorption strength of carbonaceous intermediates. Here, we report a complementary approach in which we utilize hydroxide and oxide doping of a catalyst surface to tune the adsorbed hydrogen on Cu. Density functional theory studies indicate that this doping accelerates water dissociation and changes the hydrogen adsorption energy on Cu. We synthesize and investigate a suite of metal-hydroxide-interface-doped-Cu catalysts, and find that the most efficient, Ce(OH) x -doped-Cu, exhibits an ethanol Faradaic efficiency of 43% and a partial current density of 128 mA cm −2 . Mechanistic studies, wherein we combine investigation of hydrogen evolution performance with the results of operando Raman spectroscopy, show that adsorbed hydrogen hydrogenates surface *HCCOH, a key intermediate whose fate determines branching to ethanol versus ethylene. Producing ethanol from carbon dioxide, water, and renewable electricity offers a route to sustainable energy. Here, the authors enhance electrocatalytic activity for carbon dioxide reduction by tuning adsorbed hydrogen in a class of copper catalysts with oxide- and hydroxide-modified surfaces.

Nitrogen-doped graphene-supported single atoms convert CO 2 to CO, but fail to provide further hydrogenation to methane – a finding attributable to the weak adsorption of CO intermediates. To regulate the adsorption energy, here we investigate the metal-supported single atoms to enable CO 2 hydrogenation. We find a copper-supported iron-single-atom catalyst producing a high-rate methane. Density functional theory calculations and in-situ Raman spectroscopy show that the iron atoms attract surrounding intermediates and carry out hydrogenation to generate methane. The catalyst is realized by assembling iron phthalocyanine on the copper surface, followed by in-situ formation of single iron atoms during electrocatalysis, identified using operando X-ray absorption spectroscopy. The copper-supported iron-single-atom catalyst exhibits a CO 2 -to-methane Faradaic efficiency of 64% and a partial current density of 128 mA cm −2 , while the nitrogen-doped graphene-supported one produces only CO. The activity is 32 times higher than a pristine copper under the same conditions of electrolyte and bias. Converting CO2 and H2O into value-added chemical feedstocks and fuels offers a carbon neutral approach to tackling global energy and climate concerns. Here the authors report a metal supported single-atom catalytic site enabling the electrocatalytic reduction of CO2 to methane.

Membrane electrode assembly (MEA) electrolyzers offer a means to scale up CO 2 -to-ethylene electroconversion using renewable electricity and close the anthropogenic carbon cycle. To date, excessive CO 2 coverage at the catalyst surface with limited active sites in MEA systems interferes with the carbon-carbon coupling reaction, diminishing ethylene production. With the aid of density functional theory calculations and spectroscopic analysis, here we report an oxide modulation strategy in which we introduce silica on Cu to create active Cu-SiO x interface sites, decreasing the formation energies of OCOH* and OCCOH*—key intermediates along the pathway to ethylene formation. We then synthesize the Cu-SiO x catalysts using one-pot coprecipitation and integrate the catalyst in a MEA electrolyzer. By tuning the CO 2 concentration, the Cu-SiO x catalyst based MEA electrolyzer shows high ethylene Faradaic efficiencies of up to 65% at high ethylene current densities of up to 215 mA cm −2 ; and features sustained operation over 50 h. CO 2 -to-ethylene conversion using renewable electricity provides a sustainable route to produce valuable chemicals. Here, the authors report high ethylene activity of 215 mA cm −2 and selectivity of 65% made possible by silica clusters in copper.

The renewable-electricity-powered CO 2 electroreduction reaction provides a promising means to store intermittent renewable energy in the form of valuable chemicals and dispatchable fuels. Renewable methane produced using CO 2 electroreduction attracts interest due to the established global distribution network; however, present-day efficiencies and activities remain below those required for practical application. Here we exploit the fact that the suppression of *CO dimerization and hydrogen evolution promotes methane selectivity: we reason that the introduction of Au in Cu favors *CO protonation vs. C−C coupling under low *CO coverage and weakens the *H adsorption energy of the surface, leading to a reduction in hydrogen evolution. We construct experimentally a suite of Au-Cu catalysts and control *CO availability by regulating CO 2 concentration and reaction rate. This strategy leads to a 1.6× improvement in the methane:H 2 selectivity ratio compared to the best prior reports operating above 100 mA cm −2 . We as a result achieve a CO 2 -to-methane Faradaic efficiency (FE) of (56 ± 2)% at a production rate of (112 ± 4) mA cm −2 . The electroreduction of CO 2 offers a promising approach to produce carbon-neutral methane using renewable electricity. This study shows that the introduction of Au in Cu enables selective methane production from CO 2 by regulating *CO availability.

Renewable electricity-powered CO 2 reduction to multi-carbon (C 2+ ) products offers a promising route to realization of low-carbon-footprint fuels and chemicals. However, a major fraction of input CO 2 (>85%) is consumed by the electrolyte through reactions with hydroxide to form carbonate/bicarbonate in both alkaline and neutral reactors. Acidic conditions offer a solution to overcoming this limitation, but also promote the hydrogen evolution reaction. Here we report a design strategy that suppresses hydrogen evolution reaction activity by maximizing the co-adsorption of CO and CO 2 on Cu-based catalysts to weaken H* binding. Using density functional theory studies, we found Pd–Cu promising for selective C 2+ production over C 1 , with the lowest ∆ G OCCOH* and ∆ G OCCOH* - ∆ G CHO* . We synthesized Pd–Cu catalysts and report a crossover-free system (liquid product crossover <0.05%) with a Faradaic efficiency of 89 ± 4% for CO 2 to C 2+ at 500 mA cm −2 , simultaneous with single-pass CO 2 utilization of 60 ± 2% to C 2+ . Acidic conditions present a solution to carbonate formation in CO 2 electrolysis but create a selectivity issue through competing H 2 evolution. Here, theoretical methods are used to optimize acidity and select Pd–Cu as a selective electrocatalyst for acidic CO 2 reduction with negligible carbonate crossover and high single-pass carbon efficiency.

Renewable CH 4 produced from electrocatalytic CO 2 reduction is viewed as a sustainable and versatile energy carrier, compatible with existing infrastructure. However, conventional alkaline and neutral CO 2 -to-CH 4 systems suffer CO 2 loss to carbonates, and recovering the lost CO 2 requires input energy exceeding the heating value of the produced CH 4 . Here we pursue CH 4 -selective electrocatalysis in acidic conditions via a coordination method, stabilizing free Cu ions by bonding Cu with multidentate donor sites. We find that hexadentate donor sites in ethylenediaminetetraacetic acid enable the chelation of Cu ions, regulating Cu cluster size and forming Cu-N/O single sites that achieve high CH 4 selectivity in acidic conditions. We report a CH 4 Faradaic efficiency of 71% (at 100 mA cm −2 ) with <3% loss in total input CO 2 that results in an overall energy intensity (254 GJ/tonne CH 4 ), half that of existing electroproduction routes. Conventional alkaline and neutral CO 2 -to-CH 4 systems suffer carbon loss, and recovering the lost carbon requires input energy exceeding the heating value of CH 4 . Here, the authors report a chelating strategy to obtain Cu-N/O single sites decorated Cu clusters, which enables energy- and carbon-efficient CH 4 electroproduction in an acidic system.

Electroreduction uses renewable energy to upgrade carbon dioxide to value-added chemicals and fuels. Renewable methane synthesized using such a route stands to be readily deployed using existing infrastructure for the distribution and utilization of natural gas. Here we design a suite of ligand-stabilized metal oxide clusters and find that these modulate carbon dioxide reduction pathways on a copper catalyst, enabling thereby a record activity for methane electroproduction. Density functional theory calculations show adsorbed hydrogen donation from clusters to copper active sites for the *CO hydrogenation pathway towards *CHO. We promote this effect via control over cluster size and composition and demonstrate the effect on metal oxides including cobalt(II), molybdenum(VI), tungsten(VI), nickel(II) and palladium(II) oxides. We report a carbon dioxide-to-methane faradaic efficiency of 60% at a partial current density to methane of 135 milliampere per square centimetre. We showcase operation over 18 h that retains a faradaic efficiency exceeding 55%. Electroreduction uses renewable energy to upgrade carbon dioxide to value-added chemicals and fuels. Here, the authors design a suite of ligand-stabilized metal oxide clusters to modulate the reduction pathways on a copper catalyst, enabling record activity for CO 2 -to-methane conversion.

Electrochemical conversion of CO 2 into liquid fuels, powered by renewable electricity, offers one means to address the need for the storage of intermittent renewable energy. Here we present a cooperative catalyst design of molecule–metal catalyst interfaces with the goal of producing a reaction-intermediate-rich local environment, which improves the electrosynthesis of ethanol from CO 2 and H 2 O. We implement the strategy by functionalizing the copper surface with a family of porphyrin-based metallic complexes that catalyse CO 2 to CO. Using density functional theory calculations, and in situ Raman and operando X-ray absorption spectroscopies, we find that the high concentration of local CO facilitates carbon–carbon coupling and steers the reaction pathway towards ethanol. We report a CO 2 -to-ethanol Faradaic efficiency of 41% and a partial current density of 124 mA cm −2 at −0.82 V versus the reversible hydrogen electrode. We integrate the catalyst into a membrane electrode assembly-based system and achieve an overall energy efficiency of 13%. Electrochemical conversion of CO 2 into liquid fuels, powered by renewable electricity, offers one means to address the need for the storage of intermittent renewable energy. Now, Sargent and co-workers present a cooperative catalyst design of molecule–metal interfaces to improve the electrosynthesis of ethanol from CO 2 by producing a reaction-intermediate-rich local environment.

Two-electron oxygen reduction offers a route to H 2 O 2 that is potentially cost-effective and less energy-intensive than the industrial anthraquinone process. However, the catalytic performance of the highest performing prior heterogeneous electrocatalysts to H 2 O 2 has lain well below the >300 mA cm −2 needed for capital efficiency. Herein, guided by computation, we present a supramolecular approach that utilizes oxygen functional groups in a carbon nanotube substrate that—when coupled with a cobalt phthalocyanine catalyst—improve cobalt phthalocyanine adsorption, preventing agglomeration; and that further generate an electron-deficient Co centre whose interaction with the key H 2 O 2 intermediate is tuned towards optimality. The catalysts exhibit an overpotential of 280 mV at 300 mA cm −2 with turnover frequencies over 50 s −1 in a neutral medium, an order of magnitude higher activity compared with the highest performing prior H 2 O 2 electrocatalysts. This performance is sustained for over 100 h of operation. Oxygen reduction to hydrogen peroxide is a promising alternative to replace the energy-intensive anthraquinone process in industry. Now, the hydrogen peroxide electrosynthesis performance of a carbon-supported cobalt phthalocyanine catalyst is tuned via the introduction of oxygen functional groups to the support, which optimize the electronic structure of cobalt active sites.