Due to its good visible-light photocatalytic activity and environmental friendliness, g-C3N4 has attracted much attention. The relationship between precursor type and the properties of obtained catalysts is interesting to investigate. In this work, target catalysts were prepared via the thermal polymerization of different precursors, melamine, a mixture of urea and melamine, and a mixture of melamine and cyanuric acid. The prepared g-C3N4 were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), UV–vis diffuse reflectance spectroscopy (UV–vis DRS), and scanning electron microscopy (SEM). Through the characterization and analysis, the adjusting of precursors could result in the change of the microstructure. The maximum BET surface area was 98.04 cm3g−1 through precursor controlling, more than eight times that of MCN (11.15 cm3g−1) using melamine as precursor. The thermal decomposition process was also analyzed to discuss the interaction and polymerization with precursor controlling. The introduction of melamine and cyanuric acid with melamine as precursors led to the formation of a special nanotube structure and additional function groups on the surface of g-C3N4 to increase the photocatalytic activity.

A Bi12TiO20/RGO photocatalyst with polyhedron microstructure was fabricated via the template-free hydrothermal method, and the visible-light-induced photocatalytic activity of the prepared Bi12TiO20 was also evaluated by the photocatalytic reduction of heavy metal pollutants. The structures and optical properties of the prepared Bi12TiO20/RGO were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV–vis diffuse reflectance spectrum (UV–vis DRS). The effects of the reaction time and mineralizer concentration on the formation of the Bi12TiO20 polyhedral microstructure were analyzed. The enhanced photocatalytic performances of Bi12TiO20/RGO were observed which were ascribed to the combination of the Bi12TiO20 microstructure induced photogenerated charges and the RGO nanostructure as a photogenerated charges carrier. The effect of organic acids, p-hydroxybenzoic acid (PHBA), chloroacetic acid, and citric acid on the Cr(VI) photocatalytic reduction was also discussed. This work provides an insight into the design of the bismuth-based microstructure photocatalyst towards the application for environment purification of heavy metals.