Graphitic carbon nitride (g-C3N4) microspheres (CNMS) were fabricated via a solvothermal method by using dicyandiamide and cyanuric chloride as precursors. The morphology, band structure, and defects can be simultaneously regulated by merely adjusting the concentration of precursors. Structural characterization results indicate that all the prepared samples possess spherical morphology, while the band gap decreased as the precursor concentration increased from 8 mmol (CNMS-1) to 24 mmol (CNMS-3). Besides, ultraviolet photoelectron spectroscopy results suggested that the valence band of CNMS-2 (16 mmol) was much higher than that of CNMS-1 and CNMS-3. Additionally, organic elemental analysis, X-ray photoelectron spectroscopy, and electron paramagnetic resonance results unveil the formation of nitrogen defects on the surface of prepared samples. Besides, CNMS-2 exhibits an enhanced apparent reaction rate constant of RhB degradation than that of CNMS-1 and CNMS-3. The improved apparent reaction rate constant may be due to the lowered valence band as well as the formation of nitrogen defects. This work might guide the regulation of the morphology and band structure of g-C3N4-based materials prepared via the one-pot hydrothermal method.

A new plasmonic photocatalyst Ag/Bi7Ta3O18 was fabricated by photodeposition-hydrothermal method. The phase composition, microstructure, surface areas, average pore size, UV-vis diffuse reflection spectra, and photocatalytic activities of composite photocatalysts were investigated in detail. The results of the measurements indicated that the Ag0 nanoparticle successfully loads on the surface of Bi7Ta3O18, and the 0.06 Ag/Bi7Ta3O18 photocatalysts exhibited the best photocatalytic activity for the degradation of Rhodamine B (RhB). The improved photocatalytic activity could be contributed to the localized surface plasmon resonance caused by the collective oscillation of the surface electrons of Ag nanoparticles. Additionally, the photocatalytic reaction mechanism was studied by photoluminescence photocurrent, and electron spin resonance analysis. As a result, the Ag nanoparticles onto the Bi7Ta3O18 surface enlarged the electron–hole separation, and the (˙OH) was the dominated active species of degradation RhB in the photocatalytic process.

The uniform Ag@AgBr core–shell microspheres were synthesized by a very facile wet-chemical route in aqueous solution, including a reduction process to prepare sphere-like Ag core and a deposition process to synthesize AgBr shell. X-ray diffraction, x-ray photoelectron spectroscopy, field emission scanning electron microscopy, and high-resolution transmission electron microscopy results confirmed the formation of Ag@AgBr core–shell heterostructures which had been achieved by this simple method. Field emission scanning and high-resolution transmission electron microscopy results of the as-synthesized Ag@AgBr composite revealed that AgBr particles were deposited on the surface of sphere-like Ag core. Under visible-light (λ > 420 nm) and real sunlight irradiation, the as-synthesized Ag@AgBr samples exhibit high activity and good stability for the photodegradation of Rhodamine 6G (R6G) in water. The present work suggests that the as-synthesized Ag@AgBr core–shell microsphere can be applied as a visible light-activated photocatalyst in efficient utilization of solar energy for treating water polluted by some chemically stable azo dyes in environment. The enhanced photocatalytic performance of the as-synthesized Ag@AgBr composite might be attributed to accelerated separation efficiency of electron–hole pairs on the interface of the Ag@AgBr hybrids and improved visible-light absorption abilities when AgBr is coupled with Ag.