Tunable Electrochemical Reactive Carbon Dioxide Capture and Conversion to Produce Syngas Using Highly Dispersed Nickel Catalyst

Syngas, a mixture of carbon monoxide (CO) and hydrogen (H2) is a vital feedstock for industrial processes such as Fischer–Tropsch synthesis to produce liquid fuels for various applications including transportation. In a significant departure from the production of syngas by harnessing fossil fuels, carbon dioxide (CO2) emissions are captured and converted to produce syngas. Renewable electricity-enabled CO2 electroreduction offers promising pathways for syngas production, but gas-phase electrolysis systems face challenges. These challenges include the need for high-purity CO2 by harnessing energy intensive separation processes, dependence on precious metal catalysts, and limited product selectivity. To address these challenges, an electrochemical reactive CO2 capture and conversion (E-RCC) system is developed that integrates CO2 capture with electrochemical conversion in an aqueous medium to produce high-purity syngas with a near-equimolar ratio of CO and H2. A highly dispersed Ni catalyst synthesized using porous carbon skeletons demonstrates superior performance in converting carbon species, producing nearly equimolar CO and H2 mixture at 2.5 V cell potential with a CO faradaic efficiency of 49% and corresponding current density, jCO = 11 mA/cm2, which is ideal for ethanol synthesis. The CO/H2 ratio of produced syngas can be tuned through cell voltage to achieve optimal conditions for alkane production via the Fischer–Tropsch process. Ratios of H2/CO in the range of 2–3, which are suitable for syngas and methanol synthesis, are achieved at potentials ranging from 2 V to 2.25 V. This enhanced performance is attributed to the unique atomic metal–nitrogen coordination, which effectively suppresses the hydrogen evolution reaction (HER), in contrast to Ni microparticles and Ni foam. This system offers a potential energy savings of 42%, compared with the thermal approach for syngas production. Furthermore, the investigation of the elementary reaction mechanisms reveals the critical role of proton transfer over the Ni catalyst in the electrolyzer. The reduction of *COOH to *CO is identified as the rate-limiting step under the kinetically controlled regime. By eliminating the need for high-purity CO2 and enabling conversions at room temperature, this proposed electrochemical reactive CO2 capture and conversion approach is an energy-efficient alternative to conventional thermal and electrochemical catalytic routes for syngas production.