Macro- and Nano-Porous Ag Electrodes Enable Selective and Stable Aqueous CO Reduction.

Electrochemical carbon dioxide (CO) reduction from aqueous solutions offers a promising strategy to overcome flooding and salt precipitation in gas diffusion electrodes used in gas-phase CO electrolysis. However, liquid-phase CO electrolysis often exhibits low CO reduction rates because of limited CO availability. Here, a macroporous Ag mesh is employed and activated to achieve selective CO conversion to CO with high rates from an aqueous bicarbonate solution.

Multi-metallic Layered Catalysts for Stable Electrochemical CO Reduction to Formate and Formic Acid.

Electrochemical CO reduction (ECR) to value-added products such as formate/formic acid is a promising approach for CO mitigation. Practical ECR requires long-term stability at industrially relevant reduction rates, which is challenging due to the rapid degradation of most catalysts at high current densities. Herein, we report the development of a bismuth (Bi) gas diffusion electrode on a polytetrafluoroethylene-based electrically conductive silver (Ag) substrate (Ag@Bi), which exhibits high Faradaic efficiency (FE) for formate of over 90 % in 1 M KOH and 1 M KHCO electrolytes.

High-rate and selective conversion of CO from aqueous solutions to hydrocarbons.

Electrochemical carbon dioxide (CO) conversion to hydrocarbon fuels, such as methane (CH), offers a promising solution for the long-term and large-scale storage of renewable electricity. To enable this technology, CO-to-CH conversion must achieve high selectivity and energy efficiency at high currents. Here, we report an electrochemical conversion system that features proton-bicarbonate-CO mass transport management coupled with an in-situ copper (Cu) activation strategy to achieve high CH selectivity at high currents.

Coordination Polymer Electrocatalysts Enable Efficient CO-to-Acetate Conversion.

Upgrading carbon dioxide/monoxide to multi-carbon C products using renewable electricity offers one route to more sustainable fuel and chemical production. One of the most appealing products is acetate, the profitable electrosynthesis of which demands a catalyst with higher efficiency. Here, a coordination polymer (CP) catalyst is reported that consists of Cu(I) and benzimidazole units linked via Cu(I)-imidazole coordination bonds, which enables selective reduction of CO to acetate with a 61% Faradaic efficiency at -0.

Catalyst Regeneration via Chemical Oxidation Enables Long-Term Electrochemical Carbon Dioxide Reduction.

Electrochemical CO reduction (ECR) with industrially relevant current densities, high product selectivity, and long-term stability has been a long-sought goal. Unfortunately, copper (Cu) catalysts for producing valuable multicarbon (C) products undergo structural and morphological changes under ECR conditions, especially at high current densities, resulting in a rapid decrease in product selectivity. Herein, we report a catalyst regeneration strategy, one that employs an electrolysis method comprising alternating "on" and "off" operating regimes, to increase the operating stability of a Cu catalyst.

Bipolar membrane electrolyzers enable high single-pass CO electroreduction to multicarbon products.

In alkaline and neutral MEA CO electrolyzers, CO rapidly converts to (bi)carbonate, imposing a significant energy penalty arising from separating CO from the anode gas outlets. Here we report a CO electrolyzer uses a bipolar membrane (BPM) to convert (bi)carbonate back to CO, preventing crossover; and that surpasses the single-pass utilization (SPU) limit (25% for multi-carbon products, C) suffered by previous neutral-media electrolyzers. We employ a stationary unbuffered catholyte layer between BPM and cathode to promote C products while ensuring that (bi)carbonate is converted back, in situ, to CO near the cathode.

N-Heterocyclic Carbene-Stabilized Hydrido Au Nanoclusters: Synthesis, Structure, and Electrocatalytic Reduction of CO.

Atomically precise hydrido gold nanoclusters are extremely rare but interesting due to their potential applications in catalysis. By optimization of molecular precursors, we have prepared an unprecedented N-heterocyclic carbene-stabilized hydrido gold nanocluster, [Au(NHC)ClH]. This cluster comprises a dimer of two Au kernels, each adopting an icosahedral shape with one missing vertex.

CO electrolysis to multicarbon products in strong acid.

Carbon dioxide electroreduction (COR) is being actively studied as a promising route to convert carbon emissions to valuable chemicals and fuels. However, the fraction of input CO that is productively reduced has typically been very low, <2% for multicarbon products; the balance reacts with hydroxide to form carbonate in both alkaline and neutral reactors. Acidic electrolytes would overcome this limitation, but hydrogen evolution has hitherto dominated under those conditions.

Stabilizing Highly Active Ru Sites by Suppressing Lattice Oxygen Participation in Acidic Water Oxidation.

In hydrogen production, the anodic oxygen evolution reaction (OER) limits the energy conversion efficiency and also impacts stability in proton-exchange membrane water electrolyzers. Widely used Ir-based catalysts suffer from insufficient activity, while more active Ru-based catalysts tend to dissolve under OER conditions. This has been associated with the participation of lattice oxygen (lattice oxygen oxidation mechanism (LOM)), which may lead to the collapse of the crystal structure and accelerate the leaching of active Ru species, leading to low operating stability.

Gas diffusion electrode design for electrochemical carbon dioxide reduction.

Anthropogenic carbon dioxide (CO) emissions contribute to the greenhouse effect and global warming, which can lead to undesirable climate change and extinction of species. Besides the ongoing efforts to develop environmentally benign sources of energy and to advance technologies for the capture and sequestration of CO, the transformation of emitted CO into valuable products is a pragmatic solution to curb its accumulation in the atmosphere. In this regard, electrochemical CO reduction (ECR) powered by renewable electricity provides an attractive approach because it not only converts CO to valuable fuels and chemicals but also offers a solution for the long-term storage of intermittent renewable energies.

Accelerated discovery of CO electrocatalysts using active machine learning.

The rapid increase in global energy demand and the need to replace carbon dioxide (CO)-emitting fossil fuels with renewable sources have driven interest in chemical storage of intermittent solar and wind energy. Particularly attractive is the electrochemical reduction of CO to chemical feedstocks, which uses both CO and renewable energy. Copper has been the predominant electrocatalyst for this reaction when aiming for more valuable multi-carbon products, and process improvements have been particularly notable when targeting ethylene.

Enhanced Nitrate-to-Ammonia Activity on Copper-Nickel Alloys via Tuning of Intermediate Adsorption.

Electrochemical conversion of nitrate (NO) into ammonia (NH) recycles nitrogen and offers a route to the production of NH, which is more valuable than dinitrogen gas. However, today's development of NO electroreduction remains hindered by the lack of a mechanistic picture of how catalyst structure may be tuned to enhance catalytic activity. Here we demonstrate enhanced NO reduction reaction (NORR) performance on CuNi alloy catalysts, including a 0.

Publisher Correction: Copper adparticle enabled selective electrosynthesis of n-propanol.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

CO electrolysis to multicarbon products at activities greater than 1 A cm.

Electrolysis offers an attractive route to upgrade greenhouse gases such as carbon dioxide (CO) to valuable fuels and feedstocks; however, productivity is often limited by gas diffusion through a liquid electrolyte to the surface of the catalyst. Here, we present a catalyst:ionomer bulk heterojunction (CIBH) architecture that decouples gas, ion, and electron transport. The CIBH comprises a metal and a superfine ionomer layer with hydrophobic and hydrophilic functionalities that extend gas and ion transport from tens of nanometers to the micrometer scale.

Hydration-Effect-Promoting Ni-Fe Oxyhydroxide Catalysts for Neutral Water Oxidation.

Oxygen evolution reaction (OER) catalysts that function efficiently in pH-neutral electrolyte are of interest for biohybrid fuel and chemical production. The low concentration of reactant in neutral electrolyte mandates that OER catalysts provide both the water adsorption and dissociation steps. Here it is shown, using density functional theory simulations, that the addition of hydrated metal cations into a Ni-Fe framework contributes water adsorption functionality proximate to the active sites.

Efficient upgrading of CO to C fuel using asymmetric C-C coupling active sites.

The electroreduction of C feedgas to high-energy-density fuels provides an attractive avenue to the storage of renewable electricity. Much progress has been made to improve selectivity to C and C products, however, the selectivity to desirable high-energy-density C products remains relatively low. We reason that C electrosynthesis relies on a higher-order reaction pathway that requires the formation of multiple carbon-carbon (C-C) bonds, and thus pursue a strategy explicitly designed to couple C with C intermediates.

Molecular tuning of CO-to-ethylene conversion.

The electrocatalytic reduction of carbon dioxide, powered by renewable electricity, to produce valuable fuels and feedstocks provides a sustainable and carbon-neutral approach to the storage of energy produced by intermittent renewable sources. However, the highly selective generation of economically desirable products such as ethylene from the carbon dioxide reduction reaction (CORR) remains a challenge. Tuning the stabilities of intermediates to favour a desired reaction pathway can improve selectivity, and this has recently been explored for the reaction on copper by controlling morphology, grain boundaries, facets, oxidation state and dopants.

Electrochemical CO Reduction into Chemical Feedstocks: From Mechanistic Electrocatalysis Models to System Design.

The electrochemical reduction of CO is a promising route to convert intermittent renewable energy to storable fuels and valuable chemical feedstocks. To scale this technology for industrial implementation, a deepened understanding of how the CO reduction reaction (CO RR) proceeds will help converge on optimal operating parameters. Here, a techno-economic analysis is presented with the goal of identifying maximally profitable products and the performance targets that must be met to ensure economic viability-metrics that include current density, Faradaic efficiency, energy efficiency, and stability.

Binding Site Diversity Promotes CO Electroreduction to Ethanol.

The electrochemical reduction of CO has seen many record-setting advances in C productivity in recent years. However, the selectivity for ethanol, a globally significant commodity chemical, is still low compared to the selectivity for products such as ethylene. Here we introduce diverse binding sites to a Cu catalyst, an approach that destabilizes the ethylene reaction intermediates and thereby promotes ethanol production.

N-heterocyclic carbene-functionalized magic-number gold nanoclusters.

Magic-number gold nanoclusters are atomically precise nanomaterials that have enabled unprecedented insight into structure-property relationships in nanoscience. Thiolates are the most common ligand, binding to the cluster via a staple motif in which only central gold atoms are in the metallic state. The lack of other strongly bound ligands for nanoclusters with different bonding modes has been a significant limitation in the field.

Copper adparticle enabled selective electrosynthesis of n-propanol.

The electrochemical reduction of carbon monoxide is a promising approach for the renewable production of carbon-based fuels and chemicals. Copper shows activity toward multi-carbon products from CO reduction, with reaction selectivity favoring two-carbon products; however, efficient conversion of CO to higher carbon products such as n-propanol, a liquid fuel, has yet to be achieved. We hypothesize that copper adparticles, possessing a high density of under-coordinated atoms, could serve as preferential sites for n-propanol formation.

A Surface Reconstruction Route to High Productivity and Selectivity in CO Electroreduction toward C Hydrocarbons.

Electrochemical carbon dioxide reduction (CO ) is a promising technology to use renewable electricity to convert CO into valuable carbon-based products. For commercial-scale applications, however, the productivity and selectivity toward multi-carbon products must be enhanced. A facile surface reconstruction approach that enables tuning of CO -reduction selectivity toward C products on a copper-chloride (CuCl)-derived catalyst is reported here.

Copper-on-nitride enhances the stable electrosynthesis of multi-carbon products from CO.

Copper-based materials are promising electrocatalysts for CO reduction. Prior studies show that the mixture of copper (I) and copper (0) at the catalyst surface enhances multi-carbon products from CO reduction; however, the stable presence of copper (I) remains the subject of debate. Here we report a copper on copper (I) composite that stabilizes copper (I) during CO reduction through the use of copper nitride as an underlying copper (I) species.