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Although carbon nitride (CN) catalyst has great attraction, the relatively low separation efficiency of photogenerated carriers leads to its unsatisfactory photocatalytic performance. Herein, CN/iodine-doped CN (CN/CNI) homojunction powder catalysts were fabricated via a facile water-bath combined with in-situ sintering method. The optimized CN/CNI-40% catalyst with a proper CN content shows prominent visible-light (λ > 420 nm) photocatalytic performance and stability. Its photocatalytic conversion ratio for Rhodamine B (RhB) is 5.1, 2.7, 3.0 time higher than that of CN, CNI and CNI-R (reference sample), respectively. Its photocatalytic H2 evolution rate is 5.8, 2.1, 2.2 time higher than that of CN, CNI, CNI-R, respectively. And its photocatalytic CH4 generation rate is 4.9, 3.5, 3.6 time higher than that of CN, CNI, CNI-R, respectively. This remarkably improved activity was mainly caused by the synergistic effect of CN and CNI, which can contribute to the excellent absorption performance in the 442–591 nm regions and the efficient separation of photoinduced electron-hole pairs provided by the well-matched band structures and homojunction interfaces between CN and CNI. The probable mechanism of remarkably improved photocatalytic property was also investigated. This study offers a novel and rational avenue to synthesize cheap and high-efficiency multifunctional photocatalysts applied in environmental and energy fields.

A fluorescent chemosensor (L) for Mg 2+ has been synthesized and characterized, which exhibits turn-on fluorescence response for Mg 2+ only in alcohol solvent (methanol or ethanol) with high sensitivity and selectivity. But in both nonpolar and polar solvents (cyclohexane, DCM, DMSO or MeCN), L showed negligible fluorescent response for Mg 2+ . In order to discover the unique phenomenon, optical measurements, liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) and a high performance liquid chromatography with a fluorescence detector (HPLC–FLD) of L and L with Mg 2+ ions in solvents were studied. In alcohol solvent, [L + alcohol molecule] was formed and the mechanism aspect of L concerning the remarkable fluorescence response for Mg 2+ has been discussed.

Novel In2O3/boron doped graphite-like carbon nitride (In2O3/g-C3N4B) heterojunction catalysts were successfully fabricated via a facile water-bath combined with calcination method. The resulting 5% In2O3/g-C3N4B catalyst with a proper In2O3 and B content exhibits excellent visible-light photocatalytic activities. Its conversion ratio for tetracycline hydrochloride (TH) and nitric oxide (NO) is 2.0, 1.9 times higher than that of In2O3, g-C3N4, g-C3N4B, g-C3N4B-R (reference sample), respectively. And its CH4 evolution rate is 9.0, 3.6, 2.2, 2.5 times higher than that of In2O3, g-C3N4, g-C3N4B, g-C3N4B-R, respectively. The remarkably enhanced photocatalytic properties are mainly attributed to the result that an appropriate boron and In2O3 modified the g-C3N4 promoted the efficient separation and transfer of photoinduced electrons and holes from the heterojunction interface by the band alignment between In2O3 and g-C3N4B. The probable mechanism on the activity enhancement was also discussed. Moreover, 5% In2O3/g-C3N4B shows good activity stability as evidenced by three recycling reactions. This work offers some useful insights to design and fabricate other highly efficient and stable g-C3N4-based heterojunction multifunctional materials for energy conversion and environmental restoration applications in the near future.

Novel DyVO4/boron-doped graphitic carbon nitride (DyVO4/g-C3N4B) composite photocatalytic materials were successfully fabricated by a facile heating method, and their crystal structure, morphology, light absorption properties were analyzed by various technologies. With the increases of DyVO4 content, the visible-light photocatalytic properties of DyVO4/g-C3N4B catalysts first increase and then decrease, and the 5.7% DyVO4/g-C3N4B catalyst with a proper DyVO4 content-shows the highest photocatalytic purification performance. Its NO conversion ratio is >1.6 time higher than that of DyVO4, g-C3N4 and g-C3N4B. And its Cr(VI) reduction ratio is 2.6, 2.1 and 1.8 times higher than that of DyVO4, g-C3N4 and g-C3N4B, respectively. The obviously enhanced visible-light purification properties of 5.7% DyVO4/g-C3N4B are mainly ascribed to the fact that proper DyVO4 modified g-C3N4B promotes the efficient separation of photo-generated electron-hole pairs by the band alignment between g-C3N4B and DyVO4, as well as contributes to the narrowest band gap and the best photo-response in 420–700 nm region. Moreover, 5.7% DyVO4/g-C3N4B also shows enough catalytic stability as evidenced by the four recycling experiments. This work provides some useful insights to design and synthesize a series of novel and highly efficient g-C3N4-based composite photocatalytic materials for environmental purification applications.