Improved photocatalytic performance of Nb 4 TeO 12 particles by the surface depositing α-Bi 2 O 3

Mixed-metal oxides composed of Nb 5+ ( d 0 ) and Te 4+ ( p -) cations generally exhibit excellent optoelectronic properties due to the stereoactive lone pair of electrons in the structure. In this work, a mixed-metal niobate tellurite Nb 4 TeO 12 is prepared using solid state reaction method. The p-n junctions α-Bi 2 O 3 /Nb 4 TeO 12 are prepared via soaking the as-prepared particles and post annealing treatments. Nb 4 TeO 12 has indirect electronic transition characteristic with a band energy of 3.01 eV. The bottom of conduction band is − 0.55 eV and the top of valance band is + 2.46 eV. Surface deposits of α-Bi 2 O 3 induce the recrystallization on the particle surface. The microstructure, electrical impedance, and photocurrent properties are analyzed. The p-n junction can significantly delay the recombination between photo-created h + /e − pairs. As a consequence, significant improvement of photocatalysis in p-n junction α-Bi 2 O 3 /Nb 4 TeO 12 was realized. The rate constants of as-prepared Nb 4 TeO 12 and p-n junction α-Bi 2 O 3 /Nb 4 TeO 12 (30/100) are 4.21 × 10 −3 min −3 and 1.82 × 10 −2 min −1, respectively. The experimental results show that deposits of α-Bi 2 O 3 on the surface is effective to improve the surface light absorption and photochemical properties of the Nb 5+ −Te 4+ oxide semiconductors.