Enhanced hydrogen production coupled with ethanol electrocatalytic oxidation by flow-through self-supporting electrode

Abstract

Electrocatalytic oxidation of ethanol to value-added production is an ideal replacement of the conventional anodic oxygen evolution reaction (OER) for efficient hydrogen (H2) production due to the lower electric potential energy and higher safety. However, the sluggish mass transfer rate of reactants commonly is the crucial limitation of electrocatalytic oxidation efficiency. Here, Ni(OH)2 nanosheet is immobilized on nickel foam (NF) to fabricate a flow-through self-supporting electrode (Ni(OH)2/NF) served as anode for ethanol electrocatalytic oxidation, in coupling with high-purity H2 production at the cathode. The potential for electrocatalytic oxidation of ethanol and H2 evolution was significantly reduced by 200 mV compared to pure water splitting at 25 mA cm−2. The boundary layer thickness on the anodic electrode surface could be decreased from 86.66 μm to 66.21 μm with the flow rate increased from 0 to 0.82 cm min−1. Compared to the batch mode, The conversion rate of ethanol can be increased from 59 % to 100 % and the selectivity of acetic acid can be increased from 88 % to 100 % under the flow-through mode. The Faraday efficiency of the anode achieved an increase from 76 % to over 99 % and the H2 production of the cathode increased by 31 % under the flow-through mode.