High yield of hydrogen peroxide on modified graphite felt electrode with nitrogen-doped porous carbon carbonized by zeolitic imidazolate framework-8 (ZIF-8) nanocrystals

The aim of this work was to develop a new modified graphite felt (GF) as carbonaceous cathode for electro-Fenton (EF) application loaded with nitrogen-doped porous carbon (NPC) carbonized by zeolitic imidazolate framework-8 (ZIF-8) nanocrystals as carbon precursor. At initial pH 7, the highest generation rate of H2O2 was 0.74 mg h(-1) cm(-2) by applying 12.5 mA cm(-2) by modified cathode, but in the same condition, the GF only had 0.067 mg h(-1) cm(-2). The production efficiency increased 10 times. Additionally, phenol (50 mg L-1) could be largely removed by NPC modified cathode, the mineralization ratio and TOC reached 100% and 82.61% at 120 min of optimization condition, respectively. The NPC cathode kept its stability after 5 cycles. The materials were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and linear sweep voltammetry (ISV). The results demonstrated that a homogenous NPC covered the carbon-based material GF. The existing graphitic-N and sp(2) carbon of NPC promoted the electron transfer between carbon surface and oxygen molecules, as well as accelerated the oxygen reduction reaction (ORR) and the modified graphite felt had much higher electrocatalytic activity. In this work, several manufacturing parameters like the current, pH and load of NPC were optimized. The optimized design could improve the efficiency of new cathode with in situ electro-chemical production of H2O2 and significantly offer a potential material for degradation of organic pollutants. (C) 2019 Published by Elsevier Ltd.