Preparation Of Lignite-Based Ni/C Counter Electrode Material And Its Photoelectric Performance For DSSCs

Dye-sensitized solar cells（DSSCs）have been widely studied for their simplicity of operation and high theoretical efficiency.The counter electrodes play an irreplaceable role in the operation process.Pt,which has excellent performance,is often used as the counter electrode for DSSCs.However,the high price and low quantity of Pt greatly limit its application in DSSCs.Therefore,the development and use of low cost,high performance and alternative Pt counter electrodes are necessary for the sustainable development of DSSCs.Firstly,lignite-based Ni/C counter electrode materials were prepared from Hollin River lignite and Ni（NO₃）₂·6H₂O by medium and low temperature pyrolysis,and the effects of synthesis conditions and Ni mass percentages on their structural compositions were investigated.The physical characterization such as XRD,SEM,TEM,XPS and FT-IR were used to determine the morphology and structural composition of lignite-based Ni/C counter electrode materials.Electrochemical tests such as EIS,Tafel and CV were used to investigate their electrocatalytic activity and conductivity.The results showed that the medium and low temperature pyrolysis of lignite from the Huolinhe and the doping of appropriate amount of transition metal Ni could improve the conductivity and electrocatalytic activity of the materials,and then improve their photoelectric performance,and the photoelectric conversion efficiency of the DSSCs based on lignite-based Ni/C counter electrode was 3.42%.In order to increase the number of oxygen-containing groups that react effectively with Ni in the lignite of the Huolinhe,Huolinhe lignite was oxidized under different conditions,and the effects of different oxidation conditions on the oxygen-containing groups in the lignite were analyzed by FT-IR.Further,the lignite-based Ni/C counter electrode materials were prepared by hydrothermal method using oxidized lignite as raw material,and the effects of synthesis conditions and Ni mass percentages on their structural compositions were investigated.The results showed that the oxidized Huolinhe lignite increased the number of oxygen-containing groups,and the Ni content in the lignite-based Ni/C composites prepared by the hydrothermal method increased and was well distributed,which in turn enhanced their electrocatalytic activity and led to the increase of the photoelectric conversion efficiency of DSSCs to 4.56%,which was significantly higher than that of the lignite-based Ni/C counter electrode cells prepared by the medium and low temperature pyrolysis method.