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1.
J Colloid Interface Sci ; 627: 438-448, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-35868039

RESUMO

As a novel chalcogenide photocatalyst, MnPS3 suffered from limited visible light absorption, high photogenerated electron-hole recombination, and low hole oxidation capability due to its high valence band (VB) potential. In this work, the novel MnPS3 nanosheets-Nitrogen-doped carbon dots (NCDs) composites were fabricated by immobilizing NCDs with terminal amine groups on Na+ intercalated MnPS3 nanosheets for a greatly enhanced photocatalytic hydrogen production activity. MnPS3 nanosheets of 400 nm with Mn2+ vacancies are produced in high yield by NaCl intercalation and subsequent exfoliation in N-methylpyrrolidone (NMP). NCDs with 5 nm are evenly loaded on the surface of MnPS3 nanosheets of 400 nm via strong chemical interactions of ammonium sulfate salts formed at the interface. The MnPS3-NCDs composites exhibit enhanced light absorption at 500-600 nm, reduced charge recombination and notably promoted photocatalytic activity in relative to neat MnPS3 nanosheets. MnPS3-NCDs composite with the NCDs content of 16.5% possessed the highest photocatalytic hydrogen evolution rate of 339.63 µmol·g-1·h-1 with good cycling stability, which is 9.17 times that of exfoliated MnPS3 nanosheets. The type-II MnPS3-NCDs heterojunction is conducive to the efficient interfacial carrier transport and the significantly improved photocatalytic hydrogen generation activity. Our work confirmed that the non-toxic MnPS3 could possess photocatalytic performance comparable to CdS, which will be promising to become an attractive visible-light driven photocatalyst in environmental purification and energy applications.

2.
J Colloid Interface Sci ; 606(Pt 1): 848-859, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34425272

RESUMO

The extended light absorption and the prevented charge recombination are crucial for the graphitic carbon nitride (g-C3N4) based photocatalytic materials. Herein, nonstoichiometric molybdenum oxide (MoO3-x) nanorods with oxygen vacancies were synthesized by a hydrothermal method with trace amount of oleylamine, and the Z-scheme two-dimentional (2D)/one-dimentional (1D) g-C3N4/MoO3-x composites were prepared by a facile electrostatic assembling approach. The blue MoO3-x nanorods with oxygen vacancies are loaded uniformly on the g-C3N4 nanosheets. The g-C3N4/MoO3-x composite materials exhibit strong absorption in the visible and near-infrared light regions, and the improved charge separation efficiency through the Z-scheme charge transfer mechanism. The g-C3N4/MoO3-x composite presents a significantly improved photocatalytic hydrogen generation activity with good cycling stability compared with sonicated g-C3N4 nanosheets. The best hydrogen generation activity of 209.2 µmol·h-1 under solar light irradiation and the highest apparent quantum efficiency of 4.4% irradiated at 365 nm are obtained by the g-C3N4/MoO3-x composite with a mass percent of 27.5%, which is 2.63 times of g-C3N4. The weight ratios and the content of oxygen vacancies in the small-size MoO3-x nanorods have a significant influence on the photocatalytic hydrogen performance. Moreover, effective photocatalytic overall water splitting can be achieved with the H2 and O2 evolution rates of 0.755 and 0.368 µmol∙h-1 by the g-C3N4/MoO3-x composite. The novel g-C3N4/MoO3-x composite will have broad prospects in the field of photocatalytic applications.

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