Direct Synthesis of Pure H2O2 Aqueous Solution by CoTPP/Ketjen-Black Electrocatalyst and the Fuel Cell Reactor

Hydrogen peroxide as an important and green oxidant for chemical process is manufactured by the anthraquinone (AQ) process, which is an indirect synthesis method and consumes a large quantity of energy. We have reported the direct and efficient synthesis of pure H2O2 aqueous solutions by O2 and H2 fuel-cell reactions using the Co-N-C compound cathode. Catalysis of Co-N-C-compound was improved in this work. Precursors of Co-N-C compounds were prepared by impregnation of 5,10,15,20-tetrakis(phenyl)-21H, 23H-porphyrin cobalt (II) (CoTPP) on various carbon materials. Effects of carbon materials, heat-treatment temperatures, Co loadings of the precursors on the electrocatalysis for H2O2 synthesis were studied from a current density (j), a H2O2 formation rate (R(H2O2)), a H2O2 concentration (C(H2O2)) and a faradic efficiency for H2O2 formation (FE(H2O2)). The most active and effective Co-N-C electrocatalyst is Ketjen-Black supported CoTPP (0.05 Co-wt%) activated at 1023 K in He stream as denoted 0.05 wt%/CoTPP/KB(1023 K) and shows a highest C(H2O2) and FE(H2O2) of 5.5 mol dm−3 (18.7 wt%) and 55%, respectively, with a high Co turnover-frequency of 26 s−1. Effects of amounts of the 0.05 wt%/CoTPP/KB(1023 K) electrocatalyst coated on the VGCF-base cathode were studied on the H2O2 synthesis and distributions of open-circuit voltages as electromotive forces to cathode and anode over-potentials and an IR-drop (VGCF: vapor-growing carbon fiber).