Dinh Cung Tien Nguyen

Synthesis of mesoporous SiO2/Cu2O–graphene nanocomposites and their highly efficient photocatalytic performance for dye pollutants

A mesoporous SiO2/Cu2O–graphene composite, a novel material, was successfully synthesized using a self-assembly method with tetraethyl orthosilicate (TEOS). During the reaction, Cu2O and silica nanoparticles were loaded on the graphene sheets. The mesoporous structure, morphology, pore diameter, pore volume, and surface area of the mesoporous SiO2/Cu2O–graphene composite photocatalysts were obtained via X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), Raman spectroscopy, ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectroscopy (XPS), FT-IR spectra, nitrogen adsorption/desorption isotherms using the BET and BJH method and photocurrent analyses. The photocatalytic degradation of rhodamine B (RhB), methylene blue trihydrate (MB), and reactive black B (RBB) in an aqueous solution under visible light irradiation was observed via UV spectrophotometry after measuring the decrease in their concentrations. The mesoporous structure of silica nanoparticles with a large surface plays a major role in the increased photodegradation as well as in the decomposition by the catalysts. Through recycling experiments, we conclude that the mesoporous SiO2/Cu2O–graphene composite had good stability during photocatalysis under visible light irradiation. The mesoporous SiO2/Cu2O–graphene nanocomposite is expected to become a candidate material for photodegradation with excellent performance.

A facile route to synthesize ternary Cu2O quantum dot/graphene-TiO2 nanocomposites with an improved photocatalytic effect

ABSTRACT A Cu2O quantum dot/graphene-TiO2 composite, a novel material, was successfully synthesized using a facile hydrothermal method. The hydrothermal reaction was used to load the Cu2O and TiO2 particles onto graphene sheets, and the resulting photocatalysts were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, transmission electron microscopy (TEM), Raman spectroscopy, and ultraviolet-visible (UV-vis) diffuse reflectance spectroscopy (DRS). UV spectrophotometry was employed to measure the decrease in the concentration of rhodamine B (RhB), methylene blue trihydrate (MB), and reactive black B (RBB) dyes in an aqueous solution after degradation with the photocatalysts under irradiation with visible light. The results indicate that the quantum dot-sized Cu2O is a promising material that contributes to the photocatalytic activity of Cu2O quantum dot/graphene-TiO2 composites.

An eco-friendly synthesized mesoporous-silica particle combined with WSe 2 -graphene-TiO 2 by self-assembled method for photocatalytic dye decomposition and hydrogen production

To address the limitations of titanium dioxide (TiO2) and expand the applicability of the photocatalytic activity of TiO2,WSe2 and silica, an eco-friendly, self-assembled method for combining a silica precursor with a WSe2-graphene-TiO2 composite with cetyltrimethylammonium bromide (CTAB) as surface active agents is proposed. Firstly, for the main target, the photocatalytic degradation of organic dye solutions with different initial pH levels and catalyst dosages under visible light irradiation was surveyed. The as-synthesized sample exhibited highly efficient photocatalytic effects for the treatment of the SO dye solution in the optimal conditions of this study, which included a solution with a pH level of 11 and 0.05-gram dosage of the catalyst. Secondly, previous photocatalytic hydrogen production studies reported markedly better outcomes with SiO2/WSe2-graphene-TiO2 than with the binary WSe2-graphene and ternary WSe2-graphene-TiO2 composites under ambient conditions with and without 20% methanol sacrificing reagents. The SiO2/WSe2-graphene-TiO2 composite is promising to become a potential candidate for photocatalytic performance that performs excellently as well as offer an efficient heterosystem for hydrogen production.