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.

Cost competitive electroreduction of CO2 to CO requires electrochemical systems that exhibit partial current density (j CO) exceeding 150 mA cm–2 at cell overpotentials (|ηcell|) less than 1 V. However, achieving such benchmarks remains difficult. Here, we report the electroreduction of CO2 on a supported gold catalyst in an alkaline flow electrolyzer with performance levels close to the economic viability criteria. Onset of CO production occurred at cell and cathode overpotentials of just −0.25 and −0.02 V, respectively. High j CO (∼99, 158 mA cm–2) was obtained at low |ηcell| (∼0.70, 0.94 V) and high CO energetic efficiency (∼63.8, 49.4%). The performance was stable for at least 8 h. Additionally, the onset cathode potentials, kinetic isotope effect, and Tafel slopes indicate the low overpotential production of CO in alkaline media to be the result of a pH-independent rate-determining step (i.e., electron transfer) in contrast to a pH-dependent overall process.

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Electrochemical conversion of CO2 has been proposed both as a way to reduce CO2 emissions and as a source of renewable fuels and chemicals, but conversion rates need improvement before the process will be practical. In this article, we show that the rate of CO2 conversion per unit surface area is about 10 times higher on 5 nm silver nanoparticles than on bulk silver even though measurements on single crystal catalysts show much smaller variations in rate. The enhancement disappears on 1 nm particles. We attribute this effect to a volcano effect associated with changes of the binding energy of key intermediates as the particle size decreases. These results demonstrate that nanoparticle catalysts have unique properties for CO2 conversion.

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.

We report characterization of a non-precious metal-free catalyst for the electrochemical reduction of CO to CO; namely, a pyrolyzed carbon nitride and multiwall carbon nanotube composite. This catalyst exhibits a high selectivity for production of CO over H (approximately 98 % CO and 2 % H ), as well as high activity in an electrochemical flow cell. The CO partial current density at intermediate cathode potentials (V=-1.46 V vs. Ag/AgCl) is up to 3.5× higher than state-of-the-art Ag nanoparticle-based catalysts, and the maximum current density is 90 mA cm . The mass activity and energy efficiency (up to 48 %) were also higher than the Ag nanoparticle reference. Moving away from precious metal catalysts without sacrificing activity or selectivity may significantly enhance the prospects of electrochemical CO reduction as an approach to reduce atmospheric CO emissions or as a method for load-leveling in relation to the use of intermittent renewable energy sources.

The performance of a novel carbon-supported copper complex of 3,5-diamino-1,2,4-triazole (Cu-tri/C) is investigated as a cathode material using an alkaline microfluidic H(2)/O(2) fuel cell. The absolute Cu-tri/C cathode performance is comparable to that of a Pt/C cathode. Furthermore, at a commercially relevant potential, the measured mass activity of an unoptimized Cu-tri/C-based cathode was significantly greater than that of similar Pt/C- and Ag/C-based cathodes. Accelerated cathode durability studies suggested multiple degradation regimes at various time scales. Further enhancements in performance and durability may be realized by optimizing catalyst and electrode preparation procedures.

This study seeks to explore whether electrochemical reduction of CO 2 (using current US average and future low carbon electricity) will become a viable route for the reuse of CO 2 for producing synthetic fuel. This paper presents the results of a technical and economic analysis conducted for a pathway that converts CO 2 released from fossil fuel-burning power plants to diesel fuel via electrochemical reduction of CO 2 to CO and the Fischer−Tropsch process. Currently achievable performance levels for CO 2 electrolyzers and the Fischer−Tropsch process were used to compute key metrics, including (i) cost of the synthetic fuel, (ii) well-to-gate CO 2 emissions, and (iii) overall energy efficiency. An engineering and economic model framework was developed for the investigation. The discounted cash flow analysis method was employed to calculate the cost of diesel fuel using a 500 MW power plant as the CO 2 source. The model takes into account capital expenditures as well as operating costs for the reactors and auxiliaries. The final cost varies from 3.80 to 9.20 dollars per gallon in 2010 US dollars depending on the projected level of technology achieved. The WTG CO 2 emissions vary from 180% (nearly twice) to a reduction of 75% compared to that of the business as usual scenario without carbon sequestration. The well-to-gate energy efficiency varies from 41 to 65%.