Doping Modification And Electrochemical Properties Of MoO₃ Nanobelts

Molybdenum trioxide as a pseudocapacitor electrode material of supercapacitor has attracted great attention due to its low price,no pollution to the environment,and rich redox processes.However,due to the low conductivity,which seriously hinders the diffusion rate of the ions and cycle performance.It has been reported that doping can improve this defect.Based on this,we design the co doping of cations,anions and anions to improve the electrochemical performance of Mo O₃.The main tasks are as follows:(1)Mo_1-xZn_xO₃ nanobelts with 0,0.125 and 0.25 dopants were synthesized by hydrothermal method in acid atmosphere with sodium molybdate as raw material.The application of zinc doped Mo O₃nanobelts as supercapacitor electrodes was studied for the first time.Their morphology,crystal structure,dopant state and electrochemical properties were compared in detail.XRD results show that the doping Zn does not change the crystal structure,and the band gap of the material decreases after the UV diffuse reflectance spectrum test,which shows that the conductivity of the material is improved after doping Zn.In addition,a series of electrochemical tests show that the specific capacitance and the ratio/cycle performance are significantly improved after doping Zn,and the specific capacitance of Mo_0.75Zn_0.25O₃at 0.25 A/g is 423.73 F/g.At the same time,the specific capacitance of Mo_0.75Zn_0.25O₃//AC is as high as 80.16 F/g at 1 m V/s,accompanied by the energy density of20.45 W h/kg at the power density of 212.49 W/kg,and the stability retention rate of 3000cycles is 90.78%.(2)On the basis of the synthesis of Mo_0.75Zn_0.25O₃nanobelt,adding thiourea as sulfur source,Zn and S co doped molybdenum trioxide nanomaterials were synthesized by the same process.The results show that after co doping,the crystal structure of the material has not changed,the half peak width of the diffraction peak has increased resulting in smaller grain size and the morphology of the material still presents broken nanobel.After co doping,the electrochemical range of the material is changed,the capacitance is improved and the charge transfer resistance is small.The capacitance of S-Mo_0.75Zn_0.25O₃//AC is 59.21 F/g at 1 m V/s,the highest energy density is 15.84 W h/kg at the power density of 200.03 W/kg,and the stability retention rate of 3000 cycles at 1 A/g current density is 102.78%.The intrinsic characteristics of the co doped material are improved,which significantly improves the cycle performance of the capacitor device.(3)Using C₃N₆H₆ as nitrogen source,N-doped Mo O₃nanobelt were successfully synthesized by hydrothermal method and subsequent calcination.The results show that the product remains the original configuration after doping,but the morphology of the product has changed.The capacitance of N-Mo O₃was 364.01 F/g at 0.5 A/g,about 2.4 times of that of Mo O₃(153.31 F/g).In addition,the capacity of asymmetric capacitor assembled with AC is80.77 F/g at 1 m V/s,the optimal energy density is 21.76 W h/kg at 212.51 W/kg,and the capacity retention rate of 3000 cycles is 97.68%.