Preparation Of Niobium Pentoxide Composites For Photocatalytic Properties

Niobium pentoxide(Nb2O5),as a widely used semiconductor material,has the advantages of safety,non-toxicity,chemical stability and high catalytic activity.However,it has a wide band gap(Eg)of 3.4 eV and ineffective light absorption,especially in the visible and infrared light range,which largely restrict its practical applications in photocatalysis.Recently,improved solar light absorption was achieved in Nb2O5 composites photocatalytic materials.The composites are developed to broaden the light absorption and improve the efficiency of photogenerated electrons and holes separation.In this paper,the main results are as follows:(1)Nb2O5/NiC2O4 composites were designed and synthesized by a simple one-step hydrothermal method,and different proportions of composites were synthesized by controlling the ratio of Nb source and Ni source.The Nb2O5/NiC204 composite reduces the photogenerated electrons and holes recombination efficiency and greatly improves the efficiency of the photocatalysis hydrogen evolution.We prepared Nb2O5/NiC2O4 composites for photocatalysis hydrogen evolution in full spectrum.After 6 hours of illumination,the amount of H2 produced was 1869.84 μmol,and the hydrogen production rate was 6232.79 mol·g-1·h-1,which was much higher than that of Nb2O5 and NiC2O4.It is 46 times of Nb2O5 and 623 times that of NiC2O4.Moreover,the catalyst performed good cycling stability.After 30 h of continuous testing,the hydrogen yield remained more than 95%.(2)Nb2O5@NiFe-MMO rod array was synthesized on niobium foil via a hydrothermal method which exhibited excellent photocatalytic activity towards self-coupling of amine to imines.The heterojunctions effectively improved the photogenerated electrons and holes separation efficiency and presented a high conversion rate for the selective oxidation of benzylamine to imine under full spectrum light irradiation and the catalytic efficiency is also increased by 48%relative to the Nb2O5 catalyst.Hence,Nb2O5@NiFe-MMO is a promising photocatalyst for the aerobic oxidative coupling of amines under sunlight,especially since it maintains a high level of activity after five recycles.(3)Nb2O5/g-C3N4 composite was synthesized by hydrothermal method,and its morphology and structure were analyzed by XRD,XPS and SEM.When the molar ratio of Nb2O5/g-C3N4 composite material was 1:10,the catalytic efficiency was the highest,reaching 6743.4 mol·g-1,which was about 8.3 times of Nb2O5 and 1.3 times of g-C3N4.After 24 h test,the yield remained at 97%.