Investigation On The Promoted Performance For Electrocatalytic H₂O₂ Generation Over Anthraquinone Covalently Modified Carbon Materials And Its Application In Electro-fenton

As a powerful oxidation reagent,H₂O₂ has been widely used in the field of environmental protection,chemical production,etc.Meanwhile,the advantages of electrocatalytic H₂O₂ generation including low cost,green procedure,and safe operation has attracted increasing attentions.However,the widely researched cathod materials have been sufferred from the low acticity and poor stability.For this emotion,carbon fibers and carbon nanotubes covalently modified by anthraquinone were fabricated to improve its electrocatalytic performence,followed by appling in the electro-Fenton system for degradation of organic pollutants.The regulation on improving activity and stability over anthraquinone covalent modification material,as well as the degradation performance for organic pollutants including methyl orange over electro-Fenton system were systematically explored.The main works and the corresponding results in this research were as follows:（1）Improving the electrocatalytic performance for H₂O₂ production via covalent modification of carbon fiber by anthraquinone.Carbon fiber comes from the carbonization of natural skin collagen fibers.The anthraquinone covalently modified carbon fibers were obtained through the condensation reaction between amino goup in aminoanthraquinone with carboxyl in carboxylated carbon fiber.The fact that anthraquinone was covalently loaded on carbon fiber was identified through XRD,FI-IR and XPS analysis.It was found that the electrocatalytic performance for H₂O₂ generation was significantly improved after anthraquinone modification.Among all the cathod materials,20%AQ-PCFs demonstrated the highest catalytic activity,with a H₂O₂ yield of50.5 mg/L after 60 minutes reaction,which was almost 2-fold higher than that over PCFs.At the same time,excellent stability was demonstrated over 20%AQ-PCFs,with activity loss of only 4.5%after recycling for four times,which should be ascribed to the high stability of covalent bond.With the assistance of CV and LSV anylysis,the significantly improved activity for H₂O₂ generation was found to be attributed to the increased oxygen reduction onset potential（65 m V）and limiting current density（0.41 m A/cm²）.（2）Further improving the electrocatalytic performance for H₂O₂ production via covalent modification of carbon nanotubes by anthraquinone.Since larger surface area possessed by carbon nanotube,the higher activity was anticipated due to the improved mass transfer efficiency of dioxygen.The successful loading of anthraquinone on CNT was confirmed by XRD,FI-IR and XPS characterization.From the electrocatalytic performance for H₂O₂production,40%AQ-CNT displayed the highest activity,with cumulative concentration of H₂O₂ as high as 187.6 mg/L after 60 minutes reation,which was almost 3.7 times higher than that over 40%AQ-CNT.Meawhile,the yield over40%AQ-CNT was nearly 3.0-fold than that over 40%AQ-C,in which the specific surface area of carbon dust was only one tenth of that CNT,further demonstrating that the improved performace stemed from the enlarged specific surface area.Besides,40%AQ-CNT also demonstrated excellent stability,only 3.86%of activity lost after successive recycle for 3 times.In comparison,AQ/CNT,prepared through physical adsorption method,exhibited the activity loss as high as 60.11%,nealy 20.0-fold higher than that over 40%AQ-CNT.（3）Appling 40%AQ-CNT in electro-Fenton for the degradation of organic pollutants in aqueous soluton.Hydroxyl radicals are expected to be produced through Fenton reaction of in-situ generated H₂O₂ on 40%AQ-CNT.Under the experimental condition of pH of 3.0 and Fe²⁺concerntration of 0.2 mmol/L,the degradation efficiency for methyl orange,2,4-p-chlorophenol and sulfamethazine reached as high as 91.91,99.99 and 99.65%after 1 hour reaction,respectively,demonstrating a satisfacory degradation activity and wide applicability.Meanwhile,no obvious activity loss was observed after recycling for three times,exhibting an excellent reusability.Finally,through the results from radical trapping test,EPR and fluorescence measurement,the high degradation performance was deduced to be ascribed to the sustainably generated·OH,which originated from the highly efficienct utilization of in-situ produced H₂O₂,with a maxium concentration of950.0 mmol/L after 1h reaction.