Enhancing the yield of H2O2 from oxygen reduction reaction performance by hierarchically porous carbon modified active carbon fiber as an effective cathode used in electro-Fenton

The aim of this work was to study a new type of high efficiency cathode material using hierarchically porous carbon (HPC) to modify activated carbon fibers. Compared to the cathode prior to modification, the H2O2 output (up to 9.9 mg L-1) showed an increase, and the energy consumption (8.9 kWh kg(-1)) was reduced. Since it is a thin layer sheet, the synthesized HPC had many carbon particles, a high surface area, and the oxygen reduction reaction had a much higher electrocatalytic activity. In addition, the material also has a good content of sp(3)-C, defects, and fast mass transfer. These characteristics promoted the production of H2O2 when using the optimal proportion of HPC, and electricity generation of hydrogen peroxide showed a tenfold improvement. Additionally, after being reused 5 times, the modified cathode still demonstrated stable performance. A series of characterization analyses to further demonstrate the superiority of this electrode found that the presence of HPC accelerates the electron transfer rate and facilitates oxygen reduction reactions (ORRs) on the electrode surface. When this cathode is used in an electro-Fenton system, phenol can be almost completely degraded, and up to 93.8% of the organic carbon was removed, which is a 5 fold increase compared to the ACF. The use of the HPC-loaded cathode in the EF system significantly strengthened the yield of hydrogen peroxide and effectively degraded organic pollutants with a lower energy consumption.