Multiscale design for high-performance glycolic acid electro-synthesis cell: Preparation of nanoscale-IrO2-applied Ti anode and optimization of cell assembling

摘要

Performance of a polymer electrolyte alcohol electrosynthesis cell (PEAEC) using a glycolic acid (GC)/oxalic acid (OX) redox couple was enhanced via the multiscale approach, i.e., increase of reaction rate on an anode by employing nanometer-scale (nanoscale) IrO2 catalysts and increase of selectivity for GC production via optimization of cell structures, i.e., a millimeter-scale approach. We prepared nanoscale IrO2 anode catalyst, which is mixture of IrO2 nanoparticles (d = 3.7 +/- 1.8 nm) and their agglomerates (d < 200 nm). The linear sweep voltammetry measurement for water oxidation revealed that the nanoscale IrO2 catalyst deposited on a porous carbon paper reduces overpotential for water oxidation by 196 mV from that obtained with an anode composed of commercial microscale IrO2 grans. Furthermore, application of the nanoscale IrO2 catalyst on porous titanium paper not only improved durability but also doubly enhanced water oxidation performance. We examined various PEAEC architectures composed of the nanoscale IrO2 applied Ti anode. Both nanometer- and millimeter-scale approaches realized the best PEAEC performance for GC production, i.e., 59.4% of energy conversion efficiency with 97.1% of Faradaic efficiency for the GC production at 1.8 V and 98.9% of conversion for 3 M OX, which is an almost saturated aqueous solution at operating temperature of the PEAEC (60 degrees C).