Synthesis of g-C 3 N 4 /Nb 2 O 5 heterostructures and their application in the removal of organic pollutants under visible and ultraviolet irradiation

Abstract This paper describes the synthesis of a new series of g-C 3 N 4 /Nb 2 O 5 heterostructures and their application in the removal of organic pollutants from water, as a combined strategy of photocatalysis and adsorption processes. The heterostructures were synthesized at different weight ratios through thermal oxidation and hydrothermal treatment, leading to an uniform assembly of Nb 2 O 5 nanoparticles onto g-C 3 N 4 surface. The heterostructures exhibited improved textural and electronic properties (narrowing in band gap) when compared to pure g-C 3 N 4 and Nb 2 O 5 , respectively. Although adsorption capacities were shown to be influenced by Nb 2 O 5 content, g-C 3 N 4 was essential to increase the photocatalytic response of the g-C 3 N 4 /Nb 2 O 5 heterostructures, which displayed an enhancement of photocatalytic performance on the degradation of methylene blue and rhodamine B dyes under visible and ultraviolet irradiation. The enhanced photoactivity was explained by the increase in the lifetime of the charge carries due to formation of heterojunctions between Nb 2 O 5 and g-C 3 N 4 . A mechanistic investigation on the photocatalytic process was conducted by using different reactive scavenger species. The superoxide (O 2 −• ) radical was found to be the main active specie on the dye photodegradation activated by visible radiation.