Enhanced Catalytic Hydrogen Peroxide Production from Hydroxylamine Oxidation on Modified Activated Carbon Fibers: The Role of Surface Chemistry

Herein, direct production of hydrogen peroxide (H2O2) through hydroxylamine (NH2OH) oxidation by molecular oxygen was greatly enhanced over modified activated carbon fiber (ACF) catalysts. We revealed that the higher content of pyrrolic/pyridone nitrogen (N5) and carboxyl-anhydride oxygen could effectively promote the higher selectivity and yield of H2O2. By changing the volume ratio of the concentrated H2SO4 and HNO3, the content of N5 and surface oxygen containing groups on ACF were selectively tuned. The ACF catalyst with the highest N5 content and abundant carboxyl-anhydride oxygen containing groups was demonstrated to have the highest activity toward catalytic H2O2 production, enabling the selectivity of H2O2 over 99.3% and the concentration of H2O2 reaching 123 mmol/L. The crucial effects of nitrogen species were expounded by the correlation of the selectivity of H2O2 with the content of N5 from X-ray photoelectron spectroscopy (XPS). The possible reaction pathway over ACF catalysts promoted by N5 was also shown.