Preparation And Photocatalytic Performance Of C/Nb₂O₅ Composites By Using Wood-based Nanofibrillated Cellulose As Template

Photocatalysis is a clean and efficient technology that can use light energy to degrade organic pollutants and has been widely used in wastewater treatment.As a semiconductor material,niobium oxide(Nb2O5)has the characteristics of non-toxicity,good stability,resistance to acid corrosion,and easy handling.In recent years,it has been applied in the field of photocatalysis,but its band gap is 3.2?3.4 eV,so it can only react under ultraviolet light,which limits its application field.In order to expand the photoresponse range and improve the photocatalytic ability,C/Nb2O5 nanocomposites with different morphologies were prepared using wood-based nanofibrillated cellulose(NFC)as a template and different processes.On this basis,C/Nb2O5 nanocomposites were functionally improved and their physical and chemical properties were discussed.The photocatalytic performance of rhodamine B(Rh B)dye was tested in the simulated visible light environment,and its photocatalytic mechanism was explored by controlling pH changes and active species capture experiments.The main research contents and results obtained of this paper were as follows:(1)Preparation of C/Nb2O5 composite materials using NFC as template and preliminarystudy on photocatalytic performance C/Nb2O5 composites were obtained by calcination using TEMPO-oxidized NFC as atemplate and niobium oxalate as a precursor.The feasibility of the preparation process was explored,and the corresponding characterization results were analyzed.The photocatalytic performance of C/Nb2O5 nanocomposites was studied in the simulated visible light environment.Taken together,the three-dimensionally vertically aligned nanorod-shaped C/Nb2O5 produced by vacuum-induced self-assembly exhibited good photocatalytic performance,with an band gap of 3.01 eV,which can be activated in visible light and shown the best photocatalytic efficiency at pH?3.After 5 cycles,the photocatalytic efficiency under visible light was still 2.4 times that of ordinary C/Nb2O5.In addition,the photocatalytic mechanism and influencing factors were also investigated.The active species capture experiments proved that hydroxyl radicals and superoxide radical anions play important roles in the photodegradation process.(2)Preparation of C/Nb2O5 composites using NFC aerogel as template and study on photocatalytic performanceTEMPO-oxidized NFC and niobium oxalate were used as templates to prepare C/Nb2O5 nanocomposite with aerogel morphology through the two preparation method:step-by-step and one-step methods.The photocatalytic performance of C/Nb2O5 composites was compared in the simulated visible light environment with Rh B as the target to degrade dyes.In summary,the one-step catalyst has higher catalytic activity than the step-wise method,and the specific surface area plays a decisive role.The sample prepared by one-step method under nitrogen atmosphere had the highest photocatalytic efficiency,and the band gap was reduced to 0.92eV.It can be fully absorbed,the specific surface area was enlarged to 103.93 m2/g,and 90%of Rh B was degraded by exposure to visible light for 25 minutes,which greatly improved the photocatalytic activity.The composite catalyst still had good stability after 5 cycles of test.