Unitized Regenerative Alkaline Microfluidic Cell Based on Platinum Group Metal-Free Electrode Materials

The performance of platinum group metal (PGM)-free bifunctional electrodes, in a regenerative H-2/O-2 microfluidic cell, is examined. The system is operated in an alkaline environment at 25 degrees C. Multiwalled carbon nanotube (CNT)-supported Ni-based nanostructures, NiO-Ni/CNT, were used to catalyze the hydrogen evolution reaction (HER) and the hydrogen oxidation reaction (HOR), whereas N-doped carbon nanohorn-supported NiFeOx-CoNy (NiFeOx-CoNy/NCNH) served as oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) catalysts. The system NiO-Ni/CNT parallel to NiFeOx-CoNy/NCNH, at 25 degrees C, showed an interesting performance in fuel cell mode (ca. 15 mW cm(-2) at the maximum peak) and in electrolyzer mode (ca. 102 mW cm(-2) at 50 mA cm(-2)). The round-trip efficiency, after five consecutive operating cycles, decreased from 44.76 to 39.52%.