Sn nanoparticles on gas diffusion electrodes: Synthesis, characterization and use for continuous CO 2 electroreduction to formate

Abstract

Electrochemical reduction of CO2 has been pointed out as an interesting strategy to convert CO2 into useful chemicals. In addition, coupling CO2 electroreduction with renewable energies would allow storing electricity from intermittent renewable sources such as wind or solar power. In this work, an easy and fast method is adapted for the synthesis of pure and carbon supported Sn nanoparticles. The resulting nanoparticles have been characterized by transmission electron microscopy and their electrocatalytic properties towards CO2 reduction evaluated by cyclic voltammetry. Carbon supported Sn nanoparticles have been subsequently used to prepare Gas Diffusion Electrodes (Sn/C-GDEs). The electrodes have been characterized by scanning electron microscopy and also by cyclic voltammetry. 2Finally, the electrodes were tested on a continuous and single pass CO2 electroreduction filter-press type cell system in aqueous solution, to obtain formate at ambient pressure and temperature. These Sn/C-GDEs allow working at high current densities with low catholyte flow. Thus, for instance, at 150 mA cm -2 , a 70 % Faradaic Efficiency (FE) was obtained with a formate concentration of 2.5 g L -1 . Interestingly, by increasing the current density to 200 mA cm -2 and decreasing the flow rate, a concentration over 16 g L -1 was reached.Despite the high concentrations obtained, further research is still required to keep high FE operating at high current densities.

Formic Acid Manufacture: Carbon Dioxide Utilization Alternatives

“…The selected references and their corresponding conditions are summarized in Table 2. Data for A1.1 was obtained within the research group of the authors [15]. This work represents a relevant advance compared to previous results due to the high concentrations obtained.…”

“…CFs were determined by means of the LCA tool (cradle-to-gate approach). The CF assessment of the alternative based on a ER of CO 2 (A ER ) was performed using the experimental data of three selected available studies generating three ER scenarios labelled as A1.1, A1.2, and A1.3 [7,14,15]. A1.1 represents the current best performance within the research group of the authors.…”

“…Some of the main available processes to convert CO 2 into FA are homogeneous catalysis [6][7][8], heterogeneous catalysis [9][10][11][12], photocatalytic reduction [13], and electrochemical reduction (ER) [14,15], which share a substantial input of energy per unit of reduced CO 2 [6]. These CO 2 utilization technologies for production of FA are currently found at different stages in terms of maturity.…”

“…This work aims to compare, in terms of carbon footprint, the FA commercial production process (fossil-based) with two of the main CO 2 utilization alternatives of FA synthesis (homogeneous catalysts and the novel ER of CO 2 ) based on the latest available experimental developments [7,14,15]. Savings in terms of raw materials are also included for a more fair comparison.…”

Catholyte‐Free Electrocatalytic CO2 Reduction to Formate

“…[1][2][3][4] There are several electrochemical pathways to convert CO 2 into valuable products, [1,5,6] among which formic acid or formate has received particular attention over the past few years because the CO 2 Ri nto formic acid is regarded as as uitable reaction for industrial scale production. Interestingly,as the reaction temperature rises from 303 Kto363 K, the partial current density (PCD) of formate improves more than two times with 52.9 mA cm À2 ,despite the decrease in CO 2 solubility.…”