Dual-functional water splitting: Electro-fenton-like pollutants degradation from anode reaction and hydrogen fuel production from cathode reaction

Abstract

Electrochemical water splitting can produce H2 fuel through cathode protons reduction, but the O2 products from its anode 4-electrons water oxidation have relatively low application value and could result in the separation issue of pure H2 products. Here, we assembled an electrochemical cell using graphite electrodes and HCO3−-containing aqueous electrolyte for dual-functional water splitting. In the anode side of cell, a high concentration of ∼950 ppm H2O2 from 2-electrons water oxidation can be electrochemically produced through the initiation of HCO3−/HCO4− conversion on graphite anode. Simultaneously, H2 was produced on the graphite cathode by protons reduction with ∼99% Faraday efficiency. Further took the function of HCO3− in activating H2O2 into •OH, the resultant H2O2 products was in-situ used to drive electro-Fenton-like degradation of methylene blue and phenol. Through the optimization of potential application mode for reaction, more effective degradation of methylene blue and phenol was achieved under pulsed potential mode than that under constant potential mode. The present work provides an inspiring dual-functional water splitting as well as electro-Fenton-like degradation of organic pollutants in alkaline solution, which illumine the application prospect of electrochemical synthesis of H2O2 in HCO3−-containing electrolyte.