Preparation And Electrocatalytic Performance Of MoS₂ Composite ZIF-8-derived Carbon Electrodes

Phenol-containing wastewater is a typical industrial wastewater,which has the characteristics of high toxicity,high carcinogenicity and difficult biological treatment.Electrochemical advanced oxidation technology(EAOPs)can directly or indirectly produce strong oxidants in water,which is considered to be an effective means for the treatment of such industrial wastewater,and electrode materials are the key part of the core.MoS₂ is a typical layered transition metal sulfide.Due to its easy aggregation and stacking,it will greatly reduce the active sites at its edge and the conductivity will also decrease.To this end,in this paper,MoS₂ with two kind of morphologies(spherical and flower-shaped)was prepared and composited with ZIF-8-derived carbon(ZNC),which effectively exposed the edge active sites of MoS₂ and improved the stability of the composite and conductivity.At the same time,the prepared composite electrode was applied to the electrocatalytic degradation reaction of phenol and bisphenol A,the reaction conditions were optimized,and the reaction mechanism was preliminarily discussed.In this paper,using sodium molybdate dihydrate as molybdenum source and thiourea as sulfur source,spherical MoS₂ was prepared by hydrothermal method in PVP aqueous solution,and compounded with ZIF-8 derived carbon prepared by carbonization method,MoS₂/ZNC composite electrode was prepared.The carbonized ZIF-8-derived carbon has a regular dodecahedral structure,and MoS₂ is uniformly spherically supported on the ZNC.Mocoexists in the form of Mo⁴⁺and Mo⁶⁺,and the synergistic action of Mo⁴⁺and Mo⁶⁺improves the electron transfer ability of the composite electrode,which is conducive to the generation of strong oxidation free radicals in the reaction system.The electrocatalytic degradation of phenol and bisphenol A was carried out with Ti/TrO₂/RuO₂ as the anode and MoS₂/ZNC as the cathode.The results show that the prepared composite electrode has very good electrocatalytic activity.After 120 min,the degradation efficiency of phenol and bisphenol A in the solution were 95.1%and 94.4%,respectively.After 240 min,the degradation efficiency of COD were 87.6%and 81.8%,respectively.After 20 times of repeated use,the composite electrode still has favorable catalytic activity.Using the prepared dodecahedral ZIF-8-derived carbon as the carbon source,sodium molybdate dihydrate and thiourea were dissolved in glucose solution,and flower-like MoS₂@ZNC composites were successfully prepared by optimizing the preparation conditions.MoS₂ presents a petal-shaped nanosheet structure wrapped around the regular dodecahedron ZNC,which greatly exposes the active edge sites of MoS₂,and its core-shell structure also improves the conductivity and structural stability of the composite electrode.The prepared MoS₂@ZNC composite electrode has excellent electron transfer ability and electrocatalytic activity.Under the optimal reaction conditions,after 120 min,the degradation efficiency of phenol and bisphenol A in the solution were 98.8%and 96.1%,respectively.And the degradation efficiency of COD were 90.5%and 89.5%,respectively,after 240 min.Meanwhile,the repeated use experiment proves that MoS₂@ZNC also has very good stability.