Chemical-hydrogenation Functionalized Flow-Field in Toluene Direct Electro-hydrogenation Electrolyzer for Energy-carrier Synthesis System

抄録

The toluene-methylcyclohexane organic hydride has been expected to be a candidate of the hydrogen energy carrier system for the effective utilization of renewable energy. We have developed an electrocatalyst for the toluene electro-hydrogenation electrolyzer. However, hydrogen evolution as the side reaction decreases the current efficiency by inhibiting the toluene mass transfer. In this study, we demonstrated the effect of the toluene-methylcyclohexane chemical-hydrogenation by the loading of Pt nanoparticles in the carbon-paper as a porous flow-field. The loaded Pt in the flow-field functioned as the toluene hydrogenation catalyst with the generated hydrogen gas. This simultaneous functioning of chemical- and electro-hydrogenation in the flow-field and the catalyst layer was designed to enhance the overall apparent current efficiency. Based on the electrochemical measurement, the Pt-loaded carbon paper flow-field showed an outstanding enhancement of the current efficiency without a decrease in performance for the Pt loading from 0.5 to 0.02 mg cm⁻². The conversion from toluene to methylcyclohexane by a one-through operation of the electrolyzer achieved 92–96% by using the Pt-loaded carbon paper flow-field. Simultaneously, the cell voltage was 1.92 V at 0.4 A cm⁻² for a 0.5 mg_-Pt cm⁻² loaded carbon paper-used membrane cathode assembly based on linear sweep voltammetry.