Metal Sulfides Electrodes In Dye-sensitized Solar Cell And Supercapacitor

The development of new energy and energy storage materials has become the research hotspot of researchers.As a new type of solar cell,dye-sensitized solar cells?DSSCs?attrsact great attentions because of their merit of environmental friendliness,simple fabrication process,and abundant raw materials.The development of cheap and highly effective electrode materials to replace the expensive Pt counter electrode is one of the important scientific issues to be solved in this field.Regard to the new energy storage devices,supercapacitors show great application prospects in the automobile,mobile phone,computer,and other fields because of their high specific capacitance,high power density,and long cycle life.The exploration of effective capacitor electrode materials is the key target of this field.In order to solve above problems,a series of metal sulfide electrode materials were synthesized for dye-sensitized solar cells and supercapacitors to seek better photo-electric conversion and energy storage effects.PbS,Ag₂S,CuS,CdS,and ZnS nanoparticles were successfully synthesized via a solvothermal method according to the mechanism of liquid-solution-solid reaction by adjusting the reaction temperature and time.XRD,XPS,SEM,TEM,and N₂adsorption-desorption experiments were used to characterize the crystal structure,surface composition,internal structure,surface morphology,and particle size of these sulfides.In the DSSCs system,PbS,Ag₂S,and CuS exhibited higher electrode activity for the regeneration of organic sulfide redox couple.The power conversion efficiency of the DSSCs using the sulfide counter electrodes reached PbS?6.49%?,Ag₂S?6.11%?,and CuS?5.29%?,which was significantly higher than that of Pt counter electrode based DSSCs?3.86%?.In contrast,the power conversion efficiency of the DSSCs based on CdS and ZnS counter electrodes were only 2.45%and 1.76%.Cyclic voltammograms results showed that PbS,Ag₂S,and CuS exhibited lower reduction potential,higher peak current density,and narrower peak to peak separation as compared with Pt electrode,which indicates that the sulfide material owned better catalytic activity and electrode reversibility.Moreover,the electrochemical impedance spectroscopy and Tafel polarization curve experiments showed the three materials had lower charge transfer resistance and diffusion impedance,and higher exchange current,which also proved the high catalytic activity of PbS,Ag₂S,and CuS.In the supercapacitor system,the capacitive behaviors of these five metal sulfide electrode materials in 1 M sodium sulfate electrolyte were characterized by cyclic voltammetry,galvanostatic charge-discharge,electrochemical impedance spectroscopy,and long-term cyclic stability tests.As a result,PbS had the highest specific capacitance of303.84 F·g^-1,followed by CuS(166.05 F·g^-1),CdS(153.65 F·g^-1),Ag₂S(35.10 F·g^-1),and ZnS(21.60 F·g^-1).Whereas the specific capacitance of PbS,CuS,and CdS declined faster resulting in low capacitance retention rate.The capacitance retention rates of PbS,CuS,and CdS after 1000 cycles were 19.73%,13.51%,and 15.42%,respectively.Although Ag₂S and ZnS presented relatively lower initial specific capacitance,they showed higher capacitance retention rates,reached 92.54%?Ag₂S?and 89.80%?ZnS?after 1000 cycles.In conclusion,a series of metal sulfide electrode materials were synthesized for dye-sensitized solar cells and supercapacitors,in which PbS and CuS exhibited excellent performance in the both energy conversion and energy storage devices,while the stability of PbS and CuS as supercapacitor electrodes needed to be further improved.This work reduces effectively the cost of dye-sensitized solar and enriches research content of the supercapacitor electrode materials.