Efficient in-situ production of hydrogen peroxide using a novel stacked electrosynthesis reactor

The aim of this study was to investigate the feasibility of in situ hydrogen peroxide (H2O2) production using a novel stacked electrosynthesis reactor (SER). The SER with different electrode pairs in different spacing distances was composed of gas diffusion cathode, titanium plate anode coated with mixed metal oxides of IrO2 and Ta2O5. A sodium sulfate solution of 0.1 M was used as the supporting electrolyte in all the tests. Results showed that H2O2 production rates increased from 44 +/- 4 to 220 +/- 10 mg L-1 min(-1) with decrease of the electrode spacing from 5 to 1 mm in the SER with three electrode pairs. H2O2 concentrations increased from 89.5 +/- 2.1 to 663 +/- 15 mg L-1 when the electrode pair number increased from 1 to 9 in the SER with the electrode spacing of 2 mm. During all the tests, the maximum H2O2 production rate in the SER reached 1929 +/- 51 mg L-1 min(-1), which was 160 to 3215 times higher than those reported in the literature. The outstanding performance of SER was attributable to its high cathode specific area and small electrode spacing, which greatly decreased the total internal resistance as low as 1.15 +/- 0.15 V, resulting in the improvement of the production rate coefficient of H2O2, reduction of the applied voltage and energy consumption for H2O2 electrosynthesis. Our results demonstrated that the SER should be a promising method to enhance the generation rate and to reduce energy consumption during the in-situ H2O2 production. (C) 2017 Elsevier Ltd. All rights reserved.