Synthesis of Ordered Porous Graphitic-C_(3)N_(4) and Regularly Arranged Ta_(3)N_(5) Nanoparticles by Using Self-Assembled Silica Nanospheres as a Primary Template

摘要

Uniform-sized silica nanospheres (SNSs) assembled into close-packed structures were used as a primary template for ordered porous graphitic carbon nitride (g-C_(3)N_(4)), which was subsequently used as a hard template to generate regularly arranged Ta_(3)N_(5) nanoparticles of well-controlled size. Inverse opal g-C_(3)N_(4) structures with the uniform pore size of 20-80 nm were synthesized by polymerization of cyanamide and subsequent dissolution of the SNSs with an aqueous HF solution. Back-filling of the C_(3)N_(4) pores with tantalum precursors, followed by nitridation in an NH_(3) flow gave regularly arranged, crystalline Ta_(3)N_(5) nanoparticles that are connected with each other. The surface areas of the Ta_(3)N_(5) samples were as high as 60 m~(2)g~(-1), and their particle size was tunable from 20 to 80 nm, which reflects the pore size of g-C_(3)N_(4). Polycrystalline hollow nanoparticles of Ta_(3)N_(5) were also obtained by infiltration of a reduced amount of the tantalum source into the g-C_(3)N_(4) template. An improved photocatalytic activity for H_(2) evolution on the assembly of the Ta_(3)N_(5) nanoparticles under visible-light irradiation was attained as compared with that on a conventional Ta_(3)N_(5) bulk material with low surface area.