Selective surface enhanced Raman detection and effective photocatalytic degradation of sulfonamides antibiotic based on a flexible three-dimensional chitosan/carbon nitride/silver substrate

The prevalence of sulfonamide residues in aquatic environments poses serious environmental risks, and the sensitive detection and effective degradation of sulfonamides have attracted widespread attention. Here, the environmentally friendly chitosan (CS)/carbon nitride (CN) with three-dimensional porous structure is fabricated by freeze-drying method, and subsequently a new bifunctional flexible substrate (CS/CN/Ag) is prepared by anchoring of small sized AgNPs (6 ∼ 12 nm) on CS/CN. Importantly, the CS/CN/Ag substrate shows high adsorption capacity (∼ 83.06%) for sulfamethoxazole (SMX) solution within 20 mins and the limit of detection can be as low as 7.46 × 10-9 mol·L-1 with an enhancement factor of 3.3 × 105. Also, the CS/CN/Ag substrate displays highly selective for surface-enhanced Raman spectroscopy (SERS) detection of sulfonamides and also shows excellent SERS response for SMX in hospital wastewater samples. In addition, the photocatalytic degradation efficiency of SMX could reach as high as 99.22% within 20 mins of irradiation and the CS/CN/Ag still maintains outstanding photocatalytic performance after six cycles. Moreover, the Ag content in the CS/CN/Ag substrate is only 2.35%, and also the CS/CN/Ag exhibits good uniformity, repeatability, recyclability and stability. Therefore, this flexible and cost-effectively substrate of CS/CN/Ag shows great potential for the simultaneous SERS detection and photocatalytic degradation of pollutants in actual wastewater samples.

A portable architectonics of Al/carbon nitride/metal-organic frameworks anchored Ag nanoparticles for SERS detection and photocatalytic degradation of fungicide

In recent years, it is urgent to develop bi-functional materials for highly sensitive SERS detection and photocatalytic degradation of contaminants in water of fish pond. Herein, using 5-mercapto-1-methyltetrazole as the ligand, the tree-trunk like zeolitic imidazolate framework (ZIF-8) is induced and in-situ grown on the surface of aluminum/flower carbon nitride (Al/f-C₃N₄). Then, AgNPs are tightly anchored in ZIF-8 of Al/f-C₃N₄/ZIF-8 by strong Ag-N and Ag-S bonds, and a portable architecture of Al/f-C₃N₄/ZIF-8/Ag is successfully prepared. Results indicate that the Al/f-C₃N₄/ZIF-8/Ag architecture exhibits excellent SERS activity and the detection limit can as low as 2.15 × 10^-11 mol⋅L^-1 for crystal violet (CV, a typical fungicide). Also, the Al/f-C₃N₄/ZIF-8/Ag substrate presents good photocatalytic activity for CV molecule, and the degradation efficiency reaches 98.58% after illumination for 90 min. This is mainly due to the good adsorption capacity of ZIF-8 which can enrich more CV molecules and pull them to "hot spots" generated by Ag in Al/f-C₃N₄/ZIF-8/Ag, and thus SERS response are enhanced significantly. Besides, the strong synergistic effect of f-C₃N₄, ZIF-8 and AgNPs is also important which facilitates the separation of photogenerated electrons and holes. Thus, the designed portable and bi-functional substrate could be used as a potential material for the detection and removal of CV in practical application.

An efficient photocatalytic system composed of Ti3C2 quantum dots incorporated TiO2 nanosheets and CuWO4 nanoparticles: Fabrication and its photocatalytic activity for H2 production

It is great significance for the large-scale application of photocatalytic hydrogen production technology to development an efficient, stable and noble metal-free photocatalyst. Here, we developed a photocatalytic system consisting of...

Aluminum sheet induced flower-like carbon nitride anchored with silver nanowires for highly efficient SERS detection of trace malachite green

The sensitive detection of malachite green (MG) in aquaculture wastewater is necessary for its residual poses a great threat to the living systems. Herein, the flower-like C₃N₄ (f-C₃N₄) nanostructure induced by Al sheet in the hydrothermal process is constructed. Subsequently, Ag nanowires (AgNWs) supported on Al/f-C₃N₄ and the strong interaction between AgNWs and Al/f-C₃N₄ are confirmed by XPS, Raman spectroscopy, UV-vis diffuse reflectance and fluorescence spectroscopy. Importantly, the portable Al/f-C₃N₄/AgNWs substrate shows the outstanding SERS response for MG, which is attributed to enhanced electromagnetic effect of AgNWs on large amount of corrugated and creviced regions in the flower-like Al/f-C₃N₄ and the charge transfer among the components. Also, the prepared Al/f-C₃N₄ nanostructure provides large specific surface area and abundant "N" active sites for AgNWs, and the high enrichment ability of Al/f-C₃N₄ towards MG molecules by the strong π-π stacking interaction. The detection limit of Al/f-C₃N₄/AgNWs for MG is as low as 8.38 × 10^-12 mol L^-1. The substrate can be reproduced and reused for at least 7 cycles, and the activity can still be kept after laid up for 49 days. Importantly, it unfolds a good sensitivity and selectivity for MG in actual water sample. Results indicate that the Al/f-C₃N₄/AgNWs substrate has a promising potential in practical application for trace detection of MG.

A stable and plug-and-play aluminium/titanium dioxide/metal-organic framework/silver composite sheet for sensitive Raman detection and photocatalytic removal of 4-aminothiophenol

The sensitive detection and rapid removal of 4-aminothiophenol (4-ATP, a poisonous pesticide) demand special design to potential substrates. Herein, a metal-organic framework (ZIF-8) and Ag nanoparticles were fabricated one by one on the TiO₂ coated Al sheet, and thus the Al-TiO₂-ZIF-8-Ag sheet with sandwich structure was successfully synthesized. The cost-effective Al-TiO₂-ZIF-8-Ag sheet (3.7 wt% Ag) possessed a low detection concentration of 1 × 10^-9 M towards 4-ATP, and surface-enhanced Raman scattering (SERS) analytical enhanced factor (AEF) of the Al-TiO₂-ZIF-8-Ag was 2.6 × 10⁶, which was higher than other similar substrates. Furthermore, 4-ATP can be selectively and repeatedly detected on the Al-TiO₂-ZIF-8-Ag even through it was in real samples. It indicated that the Al-TiO₂-ZIF-8-Ag was a very active and stable SERS materials for the monitoring of 4-ATP. Importantly, the substrate exhibited faster and more efficient photocatalytic activity for 4-ATP degradation. The SERS and photocatalytic mechanisms of 4-ATP on the Al-TiO₂-ZIF-8-Ag substrate were proposed. The cost-effective Al-TiO₂-ZIF-8-Ag sheet with double function is plug-and-play, and could be used in the detection and treatment of pollutants in wastewater.

Boosting charge separation and nitrogen vacancies in graphitic carbon nitride by implanted strontium vanadate for highly efficient photocatalytic reduction of hexavalent chromium

Strontium vanadate nanoparticles embedded graphitic carbon nitride (g-C₃N₄/Sr₂V₂O₇) was facilely prepared in situ via a hydrothermal method. It was shown that the Sr₂V₂O₇ nanoparticles implanted into g-carbon nitride had a small size and high distribution. Importantly, compared with some other photocatalysts, the as-prepared g-C₃N₄/Sr₂V₂O₇ nanohybrid showed excellent photocatalytic activity for reduction of Cr(vi), and as high as 99% efficiency for Cr(vi) reduction (100 mg L⁻¹) was reached within 8 min. Moreover, its activity was hardly changed after five cycles, demonstrating that the developed g-C₃N₄/Sr₂V₂O₇ nanohybrid was highly stable and promising an efficacious disposal of Cr(vi) in water. It was confirmed that the improved charge separation owing to more nitrogen vacancies in the hybrid was the main reason for the improved performance of the g-C₃N₄-Sr₂V₂O₇ nanohybrid.

A well-dispersed strontium vanadate implanted into graphitic carbon nitride showed excellent photocatalytic activity for Cr(vi) reduction. The improved charge separation owing to more nitrogen vacancies was the main reason for its enhanced activity.

A renewable photocatalytic system with dramatic photocatalytic activity for H2 evolution and constant light energy utilization: eosin Y sensitized ZnWO4 nanoplates loaded with CuO nanoparticles

Efficient photocatalytic system with light intensity-independent energy utilization for H2 evolution.

Photocatalytic activity and the electron transport mechanism of titanium dioxide microsphere/porphyrin implanted with small size copper

To obtain efficient photocatalysts by coupling architectures, developing novel materials and elucidating the charge transport mechanism at the semiconductor interface are vital. Herein, a special nanocomposite (TiO2 microsphere/CuNPs/THPP) for photocatalytic hydrogen production was facilely fabricated with copper nanoparticles (CuNPs) as the interfacial linker of the TiO2 microspheres and meso-tetra(p-hydroxypheny)porphyrin (THPP). The assembly mode of the nanocomposite was studied in detail. It was found that the CuNPs implanted at the interface of the TiO2 microspheres and THPP can dramatically strengthen the interaction between the TiO2 microspheres and THPP, and improve the separation and transfer of photo-produced charges. Therefore, the nanocomposite displayed excellent performance for photocatalytic hydrogen production. Moreover, by recycling hydrogen production, it is demonstrated that the nanocomposite was a highly efficient and long-term stable photocatalyst. By investigating the energy band location and the charge transfer, the photocatalytic mechanism over the special nanocomposite was explored and proposed to explain the better activity of the TiO2 microsphere/CuNPs/THPP photocatalytic system. It will be helpful to provide deep insights into the construction of efficient photocatalytic systems.

Enhanced electron transfer and photocatalytic hydrogen production over the carbon nitride/porphyrin nanohybrid finely bridged by special copper

A graphitic carbon nitride/tetrakis-(4-hydroxyphenyl)porphyrin nanohybrid smartly fabricated with special Cu showed excellent photocatalytic hydrogen evolution performance.

Preparation of an Ni5P4/Ni porous composite using a Ni foam as the skeleton and its application in the treatment of large-volume effluent with a high concentration of 4-nitrophenol at room temperature

In the present work, an Ni₅P₄/Ni porous composite with a Ni foam as the skeleton was prepared through phosphorization calcination at 500 °C.

Facile preparation of Ti3+ self-doped TiO2 nanoparticles and their dramatic visible photocatalytic activity for the fast treatment of highly concentrated Cr(vi) effluent

An efficient visible photocatalyst which is suitable for the rapid removal of highly concentrated Cr(vi) for environmental therapy.

The study of a novel cobalt-implanted pyridylporphyrin/graphene oxide nanohybrid for enhanced photocatalytic hydrogen evolution and its electron transfer mechanism

A metallic cobalt nanoparticle-implanted 5,15-diphenyl-10,20-di(4-pyridyl) porphyrin (DPyP)/graphene oxide (GO) nanohybrid (GO-Co-DPyP) was facilely fabricated. By means of XPS, XRD, Raman spectroscopy and UV-vis spectroscopy, it was demonstrated that on implanting metallic cobalt nanoparticles (Co NPs) in the GO, stronger interaction between GO and DPyP can be achieved, which enlarged the included angle between DPyP and GO. The nanohybrid was benifical for light absorption and photo-induced electron transfer. Furthermore, photocatalytic activity for hydrogen evolution over the nanohybrid was investigated. We found that higher activity over the GO-Co-DPyP nanohybrid was obtained, which was about two times higher than that of Co²⁺ implanted in the GO (GO-Co²⁺-DPyP). Combined with the results of fluorescence spectra and photoelectronic spectra, the electron transfer mechanism for hydrogen evolution was clarified. This study will provide some theoretical and experimental basis for the assembly and photocatalytic performance of GO-based composites by interfacial modification.

A novel cobalt ion implanted pyridylporphyrin/graphene oxide assembly for enhanced photocatalytic hydrogen production

By facilely pre-implanting Co[Formula: see text] ions in the graphene oxide, a novel 5,15-diphenyl-10,20-di(4-pyridyl)porphyrin pillared graphene oxide was fabricated by means of electrostatic interaction and coordination interaction. It was shown that the morphology and the structure of graphene oxide and pyridylporphyrin nanocomposite were modified by introducing Co[Formula: see text] ions on the interface between graphene oxide and pyridylporphyrin. Furthermore, it was found that the photocatalytic hydrogen evolution activity over the Co[Formula: see text] ions implanted in the graphene oxide and pyridylporphyrin nanocomposite was evidently higher than in the graphene oxide and pyridylporphyrin nanocomposite without Co[Formula: see text]. This confirmed that strong interaction and efficient electron transfer between pyridylporphyrin and graphene oxide are the important reasons for the enhanced photocatalytic activity for hydrogen evolution. Subsequently, this technique will be a simple and efficient approach to optimize the transfer pathway of photogenerated electrons and to improve photocatalytic performance by implanting metal ions in the interface of nanocomposites.

A novel three-dimensional pyridine-pillared graphene assembly for enhanced electron transfer and photocatalytic hydrogen evolution

Novel 1,2-di(pyridine-4-ly)ethyne pillared GO composites with high photocatalytic activity were achieved with rare earth ions as interfacial linkers.

Graphene quantum dots supported by graphene oxide as a sensitive fluorescence nanosensor for cytochrome c detection and intracellular imaging

A new class of Cyt c detection fluorescence sensor based on graphene quantum dots supported by graphene oxide has been facilely developed. The sensor shows a high sensitivity and selectivity for Cyt c detection, and further exhibits favorable intracellular imaging in A549 cells.

Photochemical Reactions in Self-Assembled Organic Monolayers Characterized by using Scanning Tunneling Microscopy

Research on the supramolecular self-assembly behavior at interfaces is of great importance to improving the performance of nanodevices that are based on optical functional materials. In this Minireview, several photoinduced isomerization and polymerization reactions in self-assembled organic monolayers on surfaces are discussed. Typical organic molecules contain azobenzene, alkynyl, or olefins groups. The feature surface base is a highly oriented pyrolytic graphite (HOPG) surface or a gold surface. Scanning tunneling microscopy (STM) is used as a strong tool to characterize new species' structures before and after illumination.

An efficient photocatalyst used in a continuous flow system for hydrogen evolution from water: TiO2 nanotube arrays fabricated on Ti meshes

TiO₂ nanotube arrays were fabricated on metallic Ti meshes and decorated with Pt. The as-prepared TiO₂ nanotube arrays with Pt are an efficient and promising photocatalyst for the photocatalytic H₂ evolution in a continuous flow system.

Self-directedly assembled porphyrin thin films with high photoactivity

A highly photoactive porphyrin thin films were self-directedly assembled by using 5,10,15,20-tetra(4-hydroxyphenyl)porphyrin cobalt and γ-isocyanatopropyltriethoxysilane as the reactants.

Synergistic effect between eosin Y and rhodamine B on a photoelectrode coated with Pt nanoparticle-decorated graphene

A photoelectrochemical system containing eosin Y, rhodamine B and graphene loaded with Pt nanoparticles was fabricated. The synergistic effect between eosin Y and rhodamine B was explored using photoelectrochemical techniques.

Synergetic effect of Cu–Pt bimetallic cocatalyst on SrTiO3 for efficient photocatalytic hydrogen production from water

The introduction of the Cu–Pt bimetal results in a significant improvement in the photocatalytic activity of STO. The hydrogen generation rate over STO/Cu95–Pt5 was about 46.6 and 2.79 times of STO and STO/Cu100–Pt0, respectively.

Nickel(ii)-ethylenediamine tetraacetic acid sensitized silicon nanowire array: an efficient cocatalyst-free photocatalyst for photocatalytic hydrogen generation under simulated sunlight irradiation

The nickel(ii)-ethylenediamine tetraacetic acid sensitized silicon nanowire array was prepared. The as-prepared photocatalytic system possesses high activity for photocatalytic H₂ evolution under sunlight irradiation.

Redox heme-proteins mediated fluorescence of CdSe/ZnS quantum dots

The redox properties of cytochrome c (Cyt c), hemoglobin (Hb) and myoglobin (Mb) were studied based on electrostatic interactions between Thioglycolic acid (TGA) capped CdSe/ZnS quantum dots (QDs) and proteins. Results indicated that only Cyt c quenched the fluorescence of the QDs at pH>8.0. Under the optimized conditions, a significant fluorescence recovery of the QDs' system was observed when the reduced form of Cyt c incubated with TGA capped QDs, however, the reduced state of Hb and Mb resulted in a more fluorescence quenching on the same size of QDs. Interestingly, the fluorescence changes of QDs-proteins could be switched by modulating the redox potentials of proteins-attached QDs. Moreover, only the oxidized Cyt c form was reduced by the generated O2(-) that significantly enhanced the fluorescence of the QDs' system, which was also demonstrated by fluorescence imaging in HeLa cells.