Air-synth Scientific Literature / Methodology Review

Below are published scientific papers that can help introduce the science and methodology behind Air-Synth. See the abstracts for key points from the papers.

  1. High-Selectivity Electrochemical Conversion of CO2 to Ethanol using a Copper Nanoparticle/N-Doped Graphene Electrode (Sci-Hub | High-Selectivity Electrochemical Conversion of CO2to Ethanol using a Copper Nanoparticle/N-Doped Graphene Electrode. ChemistrySelect, 1(19), 6055–6061 | 10.1002/slct.201601169)

Abstract: Though carbon dioxide is a waste product of combustion, it can also be a potential feedstock for the production of fine and commodity organic chemicals, provided that an efficient means to convert it to useful organic synthons can be developed. Herein we report a common element, nanostructured catalyst for the direct electrochemical conversion of CO2 to ethanol with high Faradaic efficiency (63 % at 1.2 V vs RHE) and high selectivity (84 %) that operates in water and at ambient temperature and pressure. Lacking noble metals or other rare or expensive materials, the catalyst is comprised of Cu nanoparticles on a highly textured, N-doped carbon nanospike film. Electrochemical analysis and density functional theory (DFT) calculations suggest a preliminary mechanism in which active sites on the Cu nanoparticles and the carbon nanospikes work in tandem to control the electrochemical reduction of carbon monoxide dimer to alcohol.

  1. New insights into the electrochemical reduction of carbon dioxide on metallic
    copper surfaces (Sci-Hub | New insights into the electrochemical reduction of carbon dioxide on metallic copper surfaces. Energy & Environmental Science, 5(5), 7050 | 10.1039/c2ee21234j)

Abstract: We report new insights into the electrochemical reduction of CO2 on a metallic copper surface, enabled by the development of an experimental methodology with unprecedented sensitivity for the identification and quantification of CO2 electroreduction products. This involves a custom electrochemical cell designed to maximize product concentrations coupled to gas chromatography and nuclear magnetic resonance for the identification and quantification of gas and liquid products, respectively. We studied copper across a range of potentials and observed a total of 16 different CO2 reduction products, five of which are reported here for the first time, thus providing the most complete view of the reaction chemistry reported to date. Taking into account the chemical identities of the wide range of C 1–C 3 products generated and the potential-dependence of their turnover frequencies, mechanistic information is deduced. We discuss a scheme for the formation of multicarbon products involving enol-like surface intermediates as a possible pathway, accounting for the observed selectivity for eleven distinct C(2+) oxygenated products including aldehydes, ketones, alcohols, and carboxylic acids.

  1. Electrocatalytic Reduction of CO2 to Ethanol at Close to Theoretical Potential via Engineering Abundant Electron-Donating Cuδ+ Species (https://onlinelibrary.wiley.com/doi/10.1002/anie.202205909) (access is a bit tougher with this link)

Abstract: Electrochemical CO2 reduction to liquid multi-carbon alcohols provides a promising way for intermittent renewable energy reservation and greenhouse effect mitigation. Cuδ+ (0<δ<1) species on Cu-based electrocatalysts can produce ethanol, but the in situ formed Cuδ+ is insufficient and easily reduced to Cu0. Here a Cu2S1−x catalyst with abundant Cuδ+ (0<δ<1) species is designedly synthesized and exhibited an ultra-low over-potential of 0.19 V for ethanol production. The catalyst not only delivers an outstanding ethanol selectivity of 86.9 % and a Faradaic efficiency of 73.3 % but also provides a long-term stability of Cuδ+, gaining an economic profit based on techno-economic analysis. The calculation and in situ spectroscopic results reveal that the abundant Cuδ+ sites display electron-donating ability, leading to the decrease of the reaction barrier in the potential-determining C−C coupling step and eventually making the applied potential close to the theoretical value.

  1. Metal-Free Nitrogen-Doped Mesoporous Carbon for Electroreduction of CO2 to Ethanol (Sci-Hub | Metal-Free Nitrogen-Doped Mesoporous Carbon for Electroreduction of CO2 to Ethanol. Angewandte Chemie International Edition, 56(36), 10840–10844 | 10.1002/anie.201706777)

Abstract: CO2 electroreduction is a promising technique for satisfying both renewable energy storage and negative carbon cycle. However, it remains a challenge to convert CO2 to C2 products with high efficiency and selectivity. Herein, we report a nitrogen-doped ordered cylindrical mesoporous carbon as a robust metal-free catalyst for CO2 electroreduction, enabling the efficient production of ethanol with nearly 100% selectivity and high faradaic efficiency of 77% at −0.56 V versus the reversible hydrogen electrode. Our experiments and density functional theory calculations demonstrate that the synergetic effect of the nitrogen heteroatoms and the cylindrical channel configurations facilitates the dimerization of key CO* intermediates and the subsequent proton-electron transfers, resulting in superior electrocatalytic performance for synthesizing ethanol from CO2.