Preparation And Piezo-photocatalytic Performance Of Modified CdS Nanowires

The energy crisis and environmental pollution seriously restrict the sustainable development of human society.Photocatalytic technology has attracted people's attention because of its characteristics of clean,non-polluting,low-cost,and operate simply.Cadmium sulfide(CdS)is a common ?-? semiconductor photocatalyst.It has the advantages of a narrow bandgap(2.42 eV),strong photo response,adjustable composition,and easy preparation.It also possesses piezoelectric properties,but the problem of easy recombination of photo-generated carriers greatly limits the improvement of its photocatalytic performance.Therefore,single-phase CdS nanowires(CdS NWs)are modified in this paper,and two modified nano wires are prepared by the one-step solvothermal method:phosphorus-doped CdS nanowires(P-CdS NWs)and hexagonal/cubic heterogeneous junctions CdS nanowires(H2O2-CdS NWs).Using ultrasonic excitation piezoelectric electric field to separate the carriers inside the catalyst to improve the degradation ratio of the organic dye solution,and the mechanism of modification of CdS NWs and the piezoelectric photocatalytic is discussed.The specific work is mainly divided into the following two aspects:Using sodium dihydrogen phosphate as the doping source,P-CdS NWs were prepared by a one-step solvothermal method,and the influences of different doping content on the morphology,phase,and photocatalytic performance of the sample were studied.The research results show that when 20 mol%of phosphorus is doped,the degradation ratio of methyl orange solution(MO)with P-CdS NWs is increased by 57.6%compared with CdS NWs,and it remains stable in the 8-hour continuous photocatalysis experiment.The photocatalytic performance of the sample after vulcanization treatment is reduced,which proves that Vs can effectively inhibit the recombination of carriers.The addition of different metal cations to the photocatalytic system has different effects on the photocatalytic performance of P-CdS NWs.Fe2+ and Cu2+ can promote the conversion of hydroxyl radicals(·OH),thereby significantly improving the degradation ratio,while Co2+ consumes holes so that it is not conducive to the progress of the photocatalytic reaction.The dark ultrasonic reduction silver experiment proves that the piezoelectric electric field can effectively promote the separation of carriers,and the piezoelectric polarization effect will cause more·OH to be produced in the photocatalytic process.Add hydrogen peroxide solution to the growth solution and study the effect of H2O2 addition on the morphology,phase,and catalytic performance of CdS NWs.The results show that utilize the oxidizing properties of H2O2 can form a hexagonal/cubic heterogeneous junction.Excessive H2O2 leads to changes of morphology and cubic type agglomerations.When the addition amount is 0.5 vol%,the photocatalytic performance,piezoelectric catalytic performance,and piezoelectric photocatalytic performance are all significantly improved.Among them,compared with unmodified CdS NWs,the photocatalytic performance is improved by 80.3%,and it has good continuous photocatalytic performance.The built-in electric field of the heterogeneous junction and the piezoelectric electric field have a synergistic effect,which can obviously promote the photocatalytic activity of H2O2-CdS NWs.