Cobalt (II) oxide for efficient glycerol electrooxidation for formic acid coupled with hydrogen production

In electrolytic water systems, the kinetics of the anodic oxygen evolution reaction (OER) are slow, often requiring high overpotentials, leading to significant energy consumption. The substitution of glycerol oxidation reaction (GOR) for OER at the anode is regarded as a potential strategy to address this issue. In this work, in-situ growth of CoO on nickel foam (CoO/NF) was designed to achieve high performance of GOR. The results show that the selectivity for formic acid (FA) reached 93.3%, and the GOR Faradaic efficiency reached 91.3% at 1.3 V vs RHE. A flow cell was assembled with the CoO/NF electrode at the anode and commercial Pt/C at the cathode. The flow cell required cell voltage of only 1.6 V to achieve a current density of ≈100 mA cm−2 and showed superior stability after working for 108 hours with a slightly current attenuation of 0.56%. More importantly, at this current density level, significant FA and H2 production rates were achieved, measuring 2.23 and 1.57 mmol cm−2 h−1, respectively. The catalytic pathway and mechanism of CoO on glycerol were thoroughly investigated using series of characterizations. By coupling with electrolytic water for hydrogen production, it helps to simultaneously obtain hydrogen and high value-added product.