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Abstract Ethylene glycol is a widely utilized commodity chemical, the production of which accounts for over 46 million tons of CO₂emission annually. Here we report a paired electrocatalytic approach for ethylene glycol production from methanol. Carbon catalysts are effective in reducing formaldehyde into ethylene glycol with a 92% Faradaic efficiency, whereas Pt catalysts at the anode enable formaldehyde production through methanol partial oxidation with a 75% Faradaic efficiency. With a membrane-electrode assembly configuration, we show the feasibility of ethylene glycol electrosynthesis from methanol in a single electrolyzer. The electrolyzer operates a full cell voltage of 3.2 V at a current density of 100 mA cm⁻², with a 60% reduction in energy consumption. Further investigations, using operando flow electrolyzer mass spectroscopy, isotopic labeling, and density functional theory (DFT) calculations, indicate that the desorption of a *CH₂OH intermediate is the crucial step in determining the selectively towards ethylene glycol over methanol. 

Rational design and synthesis of efficient catalysts for electrochemical CO 2 reduction is a critical step towards practical CO 2 electrolyzer systems. In this work, we report a strategy to tune the catalytic property of a metallic Pd catalyst by coating its surface with a polydiallyldimethyl ammonium (PDDA) polymer layer. The resulting PDDA-functionalized Pd/C catalysts exhibit an enhanced CO faradaic efficiency of ∼93% together with a current density of 300 mA cm −2 at −0.65 V versus reversible hydrogen electrode in comparison to non-functionalized and commercial Pd/C catalysts. X-ray photoelectron spectroscopy analysis reveals that the improvement can be attributed to the electron transfer from the quaternary ammonium groups of PDDA to Pd nanoparticles, weakening the CO binding energy on Pd. The weak CO adsorption on Pd was further confirmed by the CO temperature programmed desorption measurement and operando attenuated total reflection-Fourier-transform infrared analysis. Therefore, the incorporation of electron-donating groups could be an effective strategy to decrease the CO binding energy of a metallic catalyst for a high CO selectivity in CO 2 electroreduction.