Synthesis Of Composite Counter Electrode Materials Based On Carbon Nanofibers And Its Application In Efficiency Dye-Sensitized Solar Cell

As a third-generation solar cell,dye-sensitized solar cells?DSSCs?has attracted much attention due to its low cost of production,high power conversion efficiency,simple production procedure,and environmental friendliness.A typical DSSCs consists of a photoanode,an electrolyte and a counter electrode?CE?.The main functions of the counter electrode are the collection of electrons and the catalysis of the redox species regeneration reaction.The performance of DSSCs depends on catalysis,electrical conductivity and stability of the counter electrode.Normally,platinum?Pt?is used as counter electrode because of its prominent catalytic activity,superior conductivity and high chemical stability.However,the high cost and rarity of Pt was the biggest obstacle for the large scale commercial application of DSSCs.Recently,many Pt-free materials have been tried in DSSCs with the hope to find a replacement for the Pt counter electrode material.This paper devotes to the development and utilization of high efficiency low Pt and Pt-free composite materials which will be applied to the CE of DSSCs,and tests the power conversion efficiencies of photovoltaic devices.?1?Rhenium-doped platinum-nickel nanostructures supported on carbon nanofibers?Re-Pt₃Ni/CNFs?were fabricated for use as CEs in dye-sensitized solar cells?DSSCs?,by a simple electrospinning technique and a hydrothermal method.The XRD test shows that the crystallinity of the nanoparticles is better than Pt₃Ni/CNFs.After Re doping,the stability of the alloy material is improved.The reduction performance of Re-Pt₃Ni/CNFs electrodes were texed using cyclic voltammetry?CV?,Tafel polarization studies?Tafel?and electrochemical impedance spectroscopy measurements?EIS?.DSSCs employing Re-Pt₃Ni/CNFs electrodes showed a higher power conversion efficiency?PCE?of 9.36%compared to solar cells with Pt,CNFs and Pt₃Ni/CNFs CEs measured under the same conditions.The excellent photoelectric performance of the Re-Pt₃Ni/CNFs CE is attributed to its stable octahedral structure and large specific surface area.Accordingly,the Re-Pt₃Ni/CNFs CE is a promising cost-effective alternative CE for DSSCs.?2?A novel electrochemical catalyst of nitrogen doped cobalt-based carbon nanofibers?Co-N-CNFs?is prepared by electrospinning technique and applied as the counter electrodes for dye-sensitized solar cells?DSSCs?.the morphology was observed by scanning electron microscope?SEM?,transmission electron microscope?TEM?,the results showed that most cobalt particles?15 nm?were uniformly embedded into the inside of Co-N-CNFs composites compared with cobalt based carbon nanofibers?Co-CNFs?and a handful were dispersed on the surface of nanofibers.The reduction performance of Co-N-CNFs electrodes were texed using CV,Tafel and EIS.The porous carbon nanofibers with large amounts of Co atoms,N-doping effect,and abundant Co-N_x clusters as catalytic active sites result in a high catalytic efficiency.The PCE for DSSCs based on Co-N-CNFs CE was 8.78%,better than that of Pt CE measured in the same condition.It can be seen that the preparation of Co-N-CNFs composite can be used as a cost-effective alternative CE for DSSCs.?3?Uniform hollow carbon-coated polydymite?Ni₃S₄?microspheres were synthesized in a solution via an in situ carbon-coating and Ostwald ripening-based route,and loaded on the surfaceof carbon nanofibers?CNFs?to fabricate the composite material of Ni₃S₄@C/CNFs.Combining spray methods,Ni₃S₄@C/CNFs were prepared as CE for DSSCs to research the photoelectric property.Because of the presence of CNFs,the transmission of electrons can be accelerated,and Ni₃S₄@C as an active site is more conducive to the reduction of I₃^-.The results showed that Ni₃S₄@C/CNFs composite obtained superior photoelectric property,higher than Pt,which is attributed to the good electrical conductivity of carbon nanofibers and the good catalytic activity of Ni₃S₄.All the results showed that the preparation of composite materials based on electrospun carbon nanofibers was an effective method to fabricate the high efficiency and low cost CE.In a word,the composite materials performed better than Pt,which greatly expand the range of CE catalytic materials.By contributing to the reduction of the cost of production for DSSCs,this research improves the competitiveness of DSSCs in photovoltaic field.