We introduce a gross-margin model to evaluate the technoeconomic feasibility of producing different C1 -C2 chemicals such as carbon monoxide, formic acid, methanol, methane, ethanol, and ethylene through the electroreduction of CO2 . Key performance benchmarks including the maximum operating cell potential (Vmax ), minimum operating current density (jmin ), Faradaic efficiency (FE), and catalyst durability (tcatdur ) are derived. The Vmax values obtained for the different chemicals indicate that CO and HCOOH are the most economically viable products. Selectivity requirements suggest that the coproduction of an economically less feasible chemical (CH3 OH, CH4 , C2 H5 OH, C2 H4 ) with a more feasible chemical (CO, HCOOH) can be a strategy to offset the Vmax requirements for individual products. Other performance requirements such as jmin and tcatdur are also derived, and the feasibility of alternative process designs and operating conditions are evaluated.

Electroreduction of carbon dioxide into higher-energy liquid fuels and chemicals is a promising but challenging renewable energy conversion technology. Among the electrocatalysts screened so far for carbon dioxide reduction, which includes metals, alloys, organometallics, layered materials and carbon nanostructures, only copper exhibits selectivity towards formation of hydrocarbons and multi-carbon oxygenates at fairly high efficiencies, whereas most others favour production of carbon monoxide or formate. Here we report that nanometre-size N-doped graphene quantum dots (NGQDs) catalyse the electrochemical reduction of carbon dioxide into multi-carbon hydrocarbons and oxygenates at high Faradaic efficiencies, high current densities and low overpotentials. The NGQDs show a high total Faradaic efficiency of carbon dioxide reduction of up to 90%, with selectivity for ethylene and ethanol conversions reaching 45%. The C2 and C3 product distribution and production rate for NGQD-catalysed carbon dioxide reduction is comparable to those obtained with copper nanoparticle-based electrocatalysts.

With the development of better catalysts, mass transport limitations are becoming a challenge to high throughput electrochemical reduction of CO 2 to CO. In contrast to optimization of electrodes for fuel cells, optimization of gas diffusion electrodes (GDE)consisting of a carbon fiber substrate (CFS), a micro porous layer (MPL), and a catalyst layer (CL)for CO 2 reduction has not received a lot of attention. Here, we studied the effect of the MPL and CFS composition on cathode performance in electroreduction of CO 2 to CO. In a flow reactor, optimized GDEs exhibited a higher partial current density for CO production than Sigracet 35BC, a commercially available GDE. By performing electrochemical impedance spectroscopy in a CO 2 flow reactor we determined that a loading of 20 wt% PTFE in the MPL resulted in the best performance. We also investigated the influence of the thickness and wet proof level of CFS with two different feeds, 100% CO 2 and the mixture of 50% CO 2 and N 2 , determining that thinner and lower wet proofing of the CFS yields better cathode performance than when using a thicker and higher wet proof level of CFS.

Electrochemical conversion of CO 2 to useful chemical intermediates may be a promising strategy to help reduce CO 2 emissions, while utilizing otherwise wasted excess renewable energy. Here we explore the effect of diluted CO 2 streams (10 to 100% by volume using N 2 as diluting inert gas) on the product selectivity and on the CO/CO 2 conversion ratio for the electrochemical reduction of CO 2 into CO, specifically using a gas diffusion electrode loaded with Ag catalyst in a continuous flow electrolyzer. When using diluted CO 2 feeds for the electrolyzer, we still observed high Faradaic efficiencies for CO (>80%), high conversion ratios (up to 32% per pass), and partial current densities for CO of 29 mA/cm 2 when operating the cell at 3.0 V. Most notably, we observed that the decrease in partial current density for CO was less than 45% when switching from a 100% CO 2 feed to a 10% CO 2 feed. Also, we studied the effect of pH and the interplay between pH and the diluted CO 2 feed. We observed higher levels of CO formation as well as a higher Faradaic efficiency for CO when using an alkaline electrolyte, compared to when using a neutral or acidic electrolyte. However, the effect of CO 2 concentration in the feed is more significant than the effect of pH on electrochemical reduction of CO 2 to CO.

The incorporation of MWCNT in the Ag electrode catalyst layer improves charge transfer within the catalyst layer, therefore significantly enhancing catalyst utilization for the electroreduction of CO2to CO.

A steady-state isothermal model is presented for the electrochemical reduction of CO 2 to CO in a microfluidic flow cell. The full cell model integrates the transport of charge, mass, and momentum with electrochemistry for both the cathode and anode. Polarization curves obtained from experiments conducted at different flow rates with varying applied cell potentials are used to determine the kinetic parameters in the electrochemical reaction rate equations. The parameterized model is validated using a different set of experimental results. Good agreement is observed, especially at high cell potentials (-2.5 to -3 V). The model is further used to analyze the effects of several operating parameters, such as applied cell potential, CO 2 concentration of the feed and feed flow rates. The use of the model to analyze the effect of design parameters, such as channel length and porosity of the gas diffusion electrodes, is also demonstrated.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.126.226.173 Downloaded on 2015-05-18 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.126.226.173 Downloaded on 2015-05-18 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.126.226.173 Downloaded on 2015-05-18 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.126.226.173 Downloaded on 2015-05-18 to IP F28 Journal of The Electrochemical Society, 162 (1) F23-F32 (2015) ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.126.226.173 Downloaded on 2015-05-18 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.126.226.173 Downloaded on 2015-05-18 to IP Journal of The Electrochemical Society, 162 (1) F23-F32 (2015) ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.126.226.173 Downloaded on 2015-05-18 to IP ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.126.226.173 Downloaded on 2015-05-18 to IPOn page F28, left column, Figure 2 should beFigure 2. Comparison of polarization curves for (a) parameter fitting and (b) model validation. Feed gas flow rate and compositions are specified inTable 2. Other operating conditions take the base case values in Table 1. ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 130.126.226.173 Downloaded on 2015-05-18 to IP

Grain boundary rich ultra-small SnO2 nanoparticles exhibited high total FEs towards electrochemical reduction of CO2 with products beyond CO and HCOO−.

On page F28, left column, Figure 2 should be