Preparation And Application Of Paper-Based Photoelectric Materials

In this paper,the In₂S₃ thin film was synthesized by growing In₂S₃ crystals on FTO glass in chemical bath,and then NiFe-LDH was loaded on the In₂S₃ film to form In₂S₃/NiFe-LDH composite film by using a hydrothermal method.The In₂S₃/NiFe-LDH composite film was used as photoelectrode to degrade xylose in aqueous medium.At the same time,the cellulose fibers were mechanically treated by a two-step beating/refining process,leading to formation of surface-nanofibrillated cellulose fibers.The surface-nanofibrillated cellulose fibers were employed to prepare transparent paper,whose properties were compared with those of nanopaper.Finally,dust-free paper was used as substrate to prepare paper-based electrodes by loading multi-walled carbon nanotubes and CoNi-LDH nanosheets through deposition and coating methods.The performances of the paper-based electrodes,CNT/LDH-CP-1and CNT/LDH-CP-2 prepred respectively by deposition and coating,and were tested.The results were as follows:The optimum temperature and time for growing In₂S₃ film on FTO conductive glass in water bath are 80oC and 3 hours.The obtained In₂S₃ film is composed of cubic?-In₂S₃ crystals.The photoelectrochemical performance of In₂S₃/NiFe-LDH composite film is much better than that of pure In₂S₃ film.Under the same voltage,the current response of In₂S₃/NiFe-LDH optoelectronic materials is about three times that of In₂S₃ optoelectronic materials,while the In₂S₃/NiFe-LDH optoelectronic materials have smaller electrochemical impedance and higher stability.The photoelectrocatalytic oxidation of xylose solution was carried out by using In₂S₃/NiFe-LDH photoelectric material as working electrode under a bias voltage of0.2 V for 3 h.The degradation rate of xylose under UV,visible and near-infrared light irridation was about 90%,80%and 50%,respetively.After distillation and purification of the oxidation product,it was found that the In₂S₃/NiFe-LDH photoelectric material can convert xylose into xylonic acid.Partially surface-nanofibrillated cellulose fibers,which were obtained by beating bleached kraft pulp with Valley beater,have a shorter average fiber length than the original fibers,surface-nanofibrils and a beating degree of 69 ^oSR.After further undergoing the refining of a PFI refiner,surface-nanofibrillated cellulose fibers with large amount of surface-nanofibrils were obtained.The beating degree of cellulose fibers reachs 90 ^oSR.However,the micro-sized backbone of cellulose fibers still occurs.After being made into paper,the surface-nanofibrillated cellulose fibers form a hierarchical fiber nework composed of micro-sized fiber backbone and nano-sized nanofibril network,in which the former are buried in the latter.Consequently,the paper made by the surface-nanofibrillated cellulose fibers has similar transparency,but has a higher thermal stability,larger tensile strength,better deformation resistance,and better flexibility than nanopaper made from cellulose nanofibers.More interestly,the formation time of transparent paper made from the surface-nanofibrillated cellulose fibers is less than 2 min,while that of nano paper made from cellulose nanofibers is more than 180 min,suggesting that the formation time of the transparent paper is much shorter that that of nanopaper.This provides a good way for preparing transparent paper in a large scale.Multi-walled carbon nanotubes and CoNi-LDH nanosheets have been detected by SEM in paper-based electrode materials CNT/LDH-CP-1 and CNT/LDH-CP-2prepared respectively by deposition and coating method on a dust-free paper substrate.Both CNT/LDH-CP-1 and CNT/LDH-CP-2 exhibit significant pseudocapacitive behavior,indicative of their electrochemical performance.The specific capacitance of the paper-based electrode material CNT/LDH-CP-1 and CNT/LDH-CP-2 were about2.66 F/g and 0.29 F/g,respectively.The CNT/LDH-CP-1 and CNT/LDH-CP-2have a capacity retention rate of approximately 76%and 41%after 1000 cycles.This observation indicates that paper-based electrode materials CNT/LDH-CP-1 and CNT/LDH-CP-2 have different capacitance and stability due to different prepation method.The CNT/LDH-CP-1 with higher amount of carbon nanotubes and CoNi-LDH possesses higher capacitance and electrochemical stability.