Electrolysis offers an attractive route to upgrade greenhouse gases such as carbon dioxide (CO2) to valuable fuels and feedstocks; however, productivity is often limited by gas diffusion through a liquid electrolyte to the surface of the catalyst. Here, we present a catalyst:ionomer bulk heterojunction (CIBH) architecture that decouples gas, ion, and electron transport. The CIBH comprises a metal and a superfine ionomer layer with hydrophobic and hydrophilic functionalities that extend gas and ion transport from tens of nanometers to the micrometer scale. By applying this design strategy, we achieved CO2 electroreduction on copper in 7 M potassium hydroxide electrolyte (pH ≈ 15) with an ethylene partial current density of 1.3 amperes per square centimeter at 45% cathodic energy efficiency.

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Exfoliated 2H molybdenum disulfide (MoS2) has unique properties and potential applications in a wide range of fields, but corresponding studies have been hampered by the lack of effective routes to it in bulk quantities. This study presents a rapid and efficient route to obtain exfoliated 2H MoS2, which combines fast sonication-assisted lithium intercalation and infrared (IR) laser-induced phase reversion. We found that the complete lithium intercalation of MoS2 with butyllithium could be effected within 1.5 h with the aid of sonication. The 2H to 1T phase transition that occurs during the lithium intercalation could be also reversed by IR laser irradiation with a DVD optical drive.

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The conversion of CO 2 to CO is demonstrated in an electrolyzer flow cell containing a bipolar membrane at current densities of 200 mA/cm 2 with a Faradaic efficiency of 50%. Electrolysis was carried out by delivering gaseous CO 2 at the cathode with a silver catalyst integrated in a carbon-based gas diffusion layer. Nonprecious nickel foam in a strongly alkaline electrolyte (1 M NaOH) was used to mediate the anode reaction. While a configuration where the anode and cathode were separated by only a bipolar membrane was found to be unfavorable for robust CO 2 reduction, a modified configuration with a solid-supported aqueous layer inserted between the silver-based catalyst layer and the bipolar membrane enhanced the cathode selectivity for CO 2 reduction to CO. We report higher current densities (200 mA/cm 2 ) than previously reported for gas-phase CO 2 to CO electrolysis and demonstrate the dependence of long-term stability on adequate hydration of the CO 2 inlet stream.

The electrochemical reduction of CO 2 has seen many record-setting advances in C 2 productivity in recent years. However, the selectivity for ethanol, a globally significant commodity chemical, is still low compared to the selectivity for products such as ethylene. Here we introduce diverse binding sites to a Cu catalyst, an approach that destabilizes the ethylene reaction intermediates and thereby promotes ethanol production. We develop a bimetallic Ag/Cu catalyst that implements the proposed design toward an improved ethanol catalyst. It achieves a record Faradaic efficiency of 41% toward ethanol at 250 mA/cm 2 and −0.67 V vs RHE, leading to a cathodic-side (half-cell) energy efficiency of 24.7%. The new catalysts exhibit an in situ Raman spectrum, in the region associated with CO stretching, that is much broader than that of pure Cu controls, a finding we account for via the diversity of binding configurations. This physical picture, involving multisite binding, accounts for the enhanced ethanol production for bimetallic catalysts, and presents a framework to design multimetallic catalysts to control reaction paths in CO 2 reductions toward desired products.

The electrolysis of CO 2 to syngas (CO + H 2 ) using nonprecious metal electrocatalysts was studied in bipolar membrane-based electrochemical cells. Electrolysis was carried out using aqueous bicarbonate and humidified gaseous CO 2 on the cathode side of the cell, with Ag or Bi/ionic liquid cathode electrocatalysts. In both cases, stable currents were observed over a period of hours with an aqueous alkaline electrolyte and NiFeO x electrocatalyst on the anode side of the cell. In contrast, the performance of the cells degraded rapidly when conventional anionand cation-exchange membranes were used in place of the bipolar membrane. In agreement with earlier reports, the Faradaic efficiency for CO 2 reduction to CO was high at low overpotential. In the liquid-phase bipolar membrane cell, the Faradaic efficiency was stable at about 50% at 30 mA/cm 2 current density. In the gas-phase cell, current densities up to 200 mA/cm 2 could be obtained, albeit at lower Faradaic efficiency for CO production. At low overpotentials in the gas-phase cathode cell, the Faradaic efficiency for CO production was initially high but dropped within 1 h, most likely because of dewetting of the ionic liquid from the Bi catalyst surface. The effective management of protons in bipolar membrane cells enables stable operation and the possibility of practical CO 2 electrolysis at high current densities.