Shuaishuai Ma

Facile Photochemical Synthesis of Au/Pt/g-C3N4 with Plasmon-Enhanced Photocatalytic Activity for Antibiotic Degradation

A novel plasmonic photocatalyst, Au/Pt/g-C3N4, was prepared by a facile calcination-photodeposition technique. The samples were characterized by X-ray diffraction, energy-dispersive spectroscopy, transmission electron microscopy, and UV-vis diffuse reflectance spectroscopy, and the results demonstrated that the Au and Pt nanoparticles (7-15 nm) were well-dispersed on the surfaces of g-C3N4. The Au/Pt codecorated g-C3N4 heterostructure displayed enhanced photocatalytic activity for antibiotic tetracycline hydrochloride (TC-HCl) degradation, and the degradation rate was 3.4 times higher than that of pure g-C3N4 under visible light irradiation. The enhancement of photocatalytic activity could be attributed to the surface plasmon resonance effect of Au and electron-sink function of Pt nanoparticles, which improve the optical absorption property and photogenerated charge carriers separation of g-C3N4, synergistically facilitating the photocatalysis process. Finally, a possible photocatalytic mechanism for degrading TC-HCl by Au/Pt/g-C3N4 heterostructure was tentatively proposed.

Photochemical synthesis of ZnO/Ag2O heterostructures with enhanced ultraviolet and visible photocatalytic activity

ZnO/Ag2O heterostructures were successfully synthesized via a simple one-step photochemical route. The samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). Photocatalytic activity toward degradation of a methylene blue (MB) aqueous solution under ultraviolet (UV) and visible light was investigated. The results showed that the as-prepared ZnO/Ag2O heterostructures significantly enhanced the UV and visible photocatalytic activity compared with pure ZnO and Ag2O. In particular, the rates of degradation using the as-prepared ZnO/Ag2O heterostructures were 27.4 and 15.6 times faster than that using bare ZnO nanoparticles under UV and visible light irradiation, respectively. Furthermore, the as-prepared ZnO/Ag2O heterostructures could be easily recycled in UV and visible photocatalytic applications due to the low concentration of surface defects. Moreover, the ZnO/Ag2O heterostructures could also degrade MB dye with high efficiency in various water types such as Changjiang river water, tap water, and deionized water, which will greatly promote their application in the area of environmental remediation.

A facile route for the preparation of ZnO/C composites with high photocatalytic activity and adsorption capacity

This manuscript describes the deposition of carbon on the surface of ZnO nanoparticles via a simple adsorption and calcination process. The prepared ZnO/C sample was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDS) and thermogravimetric analysis (TGA); the results indicated that carbon was successfully doped on the surface of the ZnO nanoparticles. The photocatalytic activity and adsorption capacity were evaluated by photocatalytic decomposition and adsorption of the dye methylene blue (MB) in aqueous solution. The results showed that the obtained ZnO/C sample exhibited much higher photocatalytic properties and adsorption capacity for MB than pure ZnO and carbon because of the formation of heteroarchitectures, which might have improved the separation of photogenerated electrons and holes. In particular, the pseudo-first-order rate constant of the ZnO/C sample was 0.326 min−1, which was 10 times greater than that of pure ZnO. Moreover, the ZnO/C composites could remove dyes from different water sources like the Changjiang River water with high efficiency as well as from deionized water, greatly promoting their application in the area of environmental remediation.

Au-loaded porous graphitic C3N4/graphene layered composite as a ternary plasmonic photocatalyst and its visible-light photocatalytic performance

A novel ternary plasmonic photocatalyst, Au-loaded porous graphitic C3N4/graphene layered composite (Au/pg-C3N4/GR), was fabricated by a facile sonication-photodeposition technique. In this hybrid structure, a polymeric semiconductor pg-C3N4 was immobilized on the surfaces of graphene sheets to form a layered composite with Au nanoparticles of sizes 10–15 nm uniformly deposited on it. The photocatalytic performance of the as-prepared Au/pg-C3N4/GR composite was evaluated by degradation of methylene blue (MB) and ciprofloxacin (CIP) as representative dye pollutant and antibiotic pollutant under visible light irradiation, respectively. The degradation rates of MB and CIP over the Au/pg-C3N4/GR photocatalyst were 4.34 and 3.05 times higher that of porous g-C3N4 (pg-C3N4), respectively, and even 7.42 and 6.09 times higher than that of pure g-C3N4, respectively. The results indicated that an improved photocatalytic efficiency was obtained when Au nanoparticles and graphene sheets co-incorporated in porous g-C3N4. The porous structure within the samples is advantageous to the adsorption capacity. The surface plasmon resonance (SPR) effect of Au and electron-acceptor role of graphene, which would improve the visible light harvesting ability, facilitate photogenerated charge carrier separation, as well as create more active reaction sites, and synergistically contribute to the enhancement of photocatalytic activity. Moreover, a possible photocatalytic mechanism was also tentatively proposed.

Fabrication of porous g-C3N4/Ag/Fe2O3 composites with enhanced visible light photocatalysis performance

Porous graphitic carbon nitride (pg-C3N4) synthetized by pyrolysis of urea was hybridized with Ag-doped Fe2O3 to form a visible-light-driven photocatalyst pg-C3N4/Ag/Fe2O3 via a simple chemical adsorption method. The obtained pg-C3N4/Ag/Fe2O3 composites with different Ag/Fe2O3 content were characterized in terms of composition, morphology, and optical properties by XRD, EDS, FT-IR, TEM and UV-vis DRS. The photocatalytic activities were evaluated by degradation of Rhodamine B (RhB) as a representative organic pollutant under visible light irradiation. The results showed Ag/Fe2O3 (5 wt%) modified pg-C3N4 exhibited excellent photocatalytic activity in the degradation of RhB and the degradation rate was 2.74 times higher than that of pure pg-C3N4. The heterostructured coupling of pg-C3N4 with a novel metal, Ag, and semiconductor, Fe2O3, in the aspect of energy level matching would effectively improve visible-light absorption capability and facilitate photogenerated electron–hole pairs separation, synergistically accounting for the enhancement of photocatalytic activity. A possible photocatalytic mechanism was also tentatively proposed.

Facile fabrication of a mpg-C3N4/TiO2 heterojunction photocatalyst with enhanced visible light photoactivity toward organic pollutant degradation

A facile hard template approach has been developed to prepare mpg-C3N4/TiO2 composites using SiO2 nanoparticles as a hard template and cyanamide as a precursor. The samples have been well characterized using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). The results demonstrate that TiO2 nanoparticles sized 5–10 nm were distributed on the surface of mpg-C3N4 to form the mpg-C3N4/TiO2 heterojunction photocatalyst. In this way, the mpg-C3N4/TiO2 heterojunction catalyst has a porous structure and large surface area, which increases the contact area for pollutants. Rhodamine B (RhB) was used as a representative organic pollutant to evaluate the photocatalytic activity of the samples under visible light irradiation. The results show that the as-prepared mpg-C3N4/TiO2 heterojunction catalyst has a significantly enhanced visible light photocatalytic activity compared to pure mpg-C3N4 and that the degradation rate was 1.6 times higher than that of pure mpg-C3N4. The increased photocatalytic activity of the mpg-C3N4/TiO2 heterojunction catalyst can be attributed to the formation of the heterojunction between mpg-C3N4 and TiO2, which suppresses the recombination of photoinduced electron–hole pairs. Furthermore, based on systematic characterization and discussion, a possible photocatalytic mechanism for the excellent photocatalytic performance was proposed.

Facile synthesis of ZnO–C nanocomposites with enhanced photocatalytic activity

This manuscript presents a facile route for the preparation of ZnO–C nanocomposites using zinc citrate dihydrate as a precursor through one-step calcination under a nitrogen atmosphere. The products were characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), Raman spectroscopy and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). The results showed ZnO nanoparticles, 5–10 nm in size, were distributed on the carbonaceous layers to form the ZnO–C nanocomposites. The as-prepared ZnO–C nanocomposites exhibited enhanced photocatalytic activity compared to pure ZnO with respect to methylene blue (MB) degradation under UV irradiation, which was attributed to the improved separation of photogenerated electrons and holes in the presence of carbonaceous layers. In particular, the rate of degradation of methylene blue (MB) with ZnO–C(550N) as a photocatalyst was 4.15 times faster than that of using bare ZnO nanoparticles. Furthermore, the ZnO–C nanocomposites could be easily recycled without an obvious decrease in photocatalytic activity. The resulting ZnO–C nanocomposites have potential applications in photocatalysis and environmental protection.

Synthesis of Ag/ZnO/C plasmonic photocatalyst with enhanced adsorption capacity and photocatalytic activity to antibiotics

A novel Ag/ZnO/C plasmonic photocatalyst was synthesized via a facile calcination and photodeposition route. Samples were characterized by X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM) and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). The results indicated that Ag and ZnO nanoparticles sized 5–10 nm were uniformly dispersed on the surface of the carbonaceous layers in Ag/ZnO/C composites. The adsorption capacity and photocatalytic activity were investigated by adsorption and photocatalytic degradation of tetracycline hydrochloride (TC-HCl) in aqueous solution. The results showed that the obtained Ag/ZnO/C sample exhibited higher adsorption capacity and enhanced UV and visible light driven photocatalytic activity to TC-HCl compared to ZnO/C and pure ZnO. With the presence of Ag nanoparticles and carbonaceous layers incorporated in the structure, the Ag/ZnO/C composites can make use of not only the UV region of sunlight, but also the visible region and efficiently promote photogenerated electron separation and transportation as well as generating more active reaction sites, which synergistically facilitate the photocatalysis process. Our present work provides a simple and new pathway for the design of ZnO-based catalysts that respond to both UV and visible light and promotes their practical application in various environmental and energy issues driven by solar light.

Enhanced visible-light photocatalytic activity of Ag2O/g-C3N4 p–n heterojunctions synthesized via a photochemical route for degradation of tetracycline hydrochloride

Ag2O/g-C3N4 p–n heterojunctions were successfully fabricated by a facile photochemical method and applied as a photocatalyst in the degradation of antibiotic tetracycline hydrochloride (TC-HCl) under visible light irradiation. The samples were well characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), and ultraviolet-visible diffuse reflectance spectroscopy (UV-vis DRS). The results demonstrated that Ag2O nanoparticles with sizes of 5–15 nm were distributed on the surface of g-C3N4 to form the Ag2O/g-C3N4 p–n heterojunctions. The heterojunctions were conducive to the high dispersibility of small Ag2O nanoparticles and the efficient separation of photogenerated electron–hole pairs, resulting in the enhancement of photocatalytic activity by using Ag2O/g-C3N4 heterojunctions as the photocatalyst compared to pure Ag2O and g-C3N4 in TC-HCl degradation. In particular, the degradation rate of TC-HCl was 1.21 and 3.52 times higher than that of pure Ag2O and g-C3N4, respectively. Furthermore, the stability of the Ag2O/g-C3N4 photocatalyst toward the degradation process under visible light irradiation was investigated.

Facile synthesis of Ag2O/N-doped helical carbon nanotubes with enhanced visible-light photocatalytic activity

Novel Ag2O/N-doped helical carbon nanotubes (Ag2O/N–HCNTs) were successfully synthesized via a simple coprecipitation method and were well characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). The photocatalytic activities were evaluated in the degradation of methylene blue (MB) aqueous solution. The results showed that Ag2O nanoparticles sized 3–10 nm were highly anchored on the surface and inner tubes of the N–HCNTs support, and significantly enhanced the visible-light photocatalytic activity compared to bare Ag2O. It was attributed to the combined effects, including highly dispersed smaller Ag2O particles and higher charge separation efficiency. The possible mechanism for the photocatalytic activity of Ag2O/N–HCNTs was also tentatively proposed. In particular, the rate of degradation of the as-prepared Ag2O/N–HCNTs was 3.9 times faster than that of using bare Ag2O nanoparticles under visible light irradiation. Furthermore, the Ag2O/N–HCNTs could be easily recycled in visible photocatalytic activity. In addition, the Ag2O/N–HCNTs could also degrade MB dye in different water sources like Changjiang River water and tap water with high efficiency as well as in deionized water and that will greatly promote their application in the area of environmental remediation.