Photoelectric Activity Research Articles

Tetrakis(4-aminophenyl) ethene-doped perylene microcrystals with strong electrochemiluminescence for biosensing applications

Perylene and its derivatives, as classical organic polycyclic aromatic hydrocarbon (PAH) ECL materials, have attracted extensive attention due to their excellent photoelectric activity and good structural controllability. As is well-known, the molecular structure of perylene is composed of five coplanar aromatic rings. There are intense π-π stacking interactions between perylene molecules, which lead to their aggregation and poor solubility in aqueous media. Unfortunately, this aggregation can weaken or even quench the emission intensity of perylene owing to the aggregation-caused quenching (ACQ) effect, finally limiting the analytical application of perylene in biological detection. In this work, perylene composite microcrystals (ETTA@Pe MCs) doped with non-planar molecular tetrakis(4-aminophenyl)ethene were synthesized in the aqueous phase by a surfactant-assisted self-assembly method. During this process, the intense π-π stacking interactions between perylene monomers were suppressed by doping. As a result, the ETTA@Pe MCs exhibited a significantly enhanced ECL signal as compared to that of perylene microcrystals (Pe MCs) in the presence of S2O82- as a co-reactant. Moreover, the ETTA@Pe MCs were utilized as a novel electrochemiluminescent (ECL) luminophores to fabricate a sensitive ECL biosensor for the quantitative analysis of dopamine (DA), which displayed a favorable linear response from 1 to 100 μmol L-1 with a detection limit of 0.96 nmol L-1.

One step preparation of CN-WS2 nanocomposite with enhanced photoactivity and its application for photoelectrochemical detection of 5-formylcytosine in the genomic DNA of maize seedling

Carbon nitride and WS2 nanocomposite (CN-WS2) with excellent photoelectric activity was prepared by one-step thermal polymerization. By the new strategy of simultaneously loading C and N elements on pure WS2, the formation of CN-WS2 brings high mobility, ultra-fast charge carrier separation and transport, and slows down the recombination rate of electrons and holes. Then, a novel photoelectrochemical biosensor was constructed for 5-formylcytosine detection based on CN-WS2 composite, aldehyde reaction probe (ARP) and ZnFe2O4, where CN-WS2 composite was employed as photoactive material, ARP was used as 5-formylcytosine capture reagent, and ZnFe2O4 was adopted as artificial mimic enzyme. Under the catalysis effect of ZnFe2O4, 4-chloro-1-naphthol was quickly oxidized by H2O2 to produce the insoluble substance of benzo-4-chlorohexadienone, which would be deposited on the electrode surface and caused a decreased PEC response. Under optimal experimental conditions, the biosensor showed low detection limit of 3 pM. This method can also discriminate 5-formylcytosine with other cytosine derivatives. More importantly, the applicability of this method was demonstrated by assessing the effect of antibiotics on the content of 5-formylcytosine in the root, stem and leave of maize seedlings.

Enhanced the photoelectrocatalytic performance of TiO2 nanotube arrays by the synergistic sensitization of Ag-AgBr nanospheres.

Ag-AgBr nanospheres were synthesized on the tubular surface of TiO2 nanotube arrays (TiO2 NTA/Ag-AgBr) by the one-pot hydrothermal deposition strategy using cetyltrimethyl ammonium bromide (CTAB) as bromine source and morphology controlling agent. The results showed that the TiO2 NTA/Ag-AgBr (0.025) prepared with 0.025 g CTAB had the uniform particle distribution, high visible light absorption, photoelectric conversion activity and photoelectrocatalytic (PEC) removal of organic dyes and heavy metal ions. The high photocatalytic decomposition of organic pollutants in waste water was attributed to the synergistic effect of Ag-AgBr nanospheres with the strong visible light response and effective separation of electron-hole pairs. The active group and photocatalytic mechanism for the rapid pollutant removal were systematically explored. This work will open the window of TiO2 NTA based photoelectrodes for the applications in solar energy conversion and dyeing waste water purification.

Novel D-A-D-Type Supramolecular Aggregates with High Photoelectric Activity for Construction of Ultrasensitive Photoelectrochemical Biosensor.

In this work, hydrazine-functionalized perylene diimide derivative supramolecular (HPDS), a novel self-enhanced donor-acceptor-donor (D-A-D) type aggregates with excellent photoelectric activity, was synthesized by a facile one-pot green route and further applied in construction of coreactant-free photoelectrochemical (PEC) biosensor for ultrasensitive DNA assay. Impressively, the HPDS formed by D-A-D units not only possessed effectively shorted electron-transfer path between donor and acceptor, but also presented a desiring aggregate state via the π-π stacking of perylene core and hydrogen bonding of the terminal moiety, thereby acquiring a high density electron flow for generating the extremely high PEC signal. Experimental data showed that the well film-formed HPDS aggregate could produce an exciting photocurrent intensity about 6-fold stronger than that of precursor perylene dianhydride with donor N2H4 in detection buffer and even 12-fold than that of perylene dianhydride only. In this respect, the resultant HPDS aggregate as a novel self-enhanced PEC signal tag was adopted to fabricate the coreactant-free PEC biosensor with the help of target dual-recycling-induced bipedal DNA walker cascade amplification strategy for ultrasensitive DNA (a fragment of TP53 gene) assay. The proposed biosensor showed a high sensitivity with a low detection limit down to femtomole level, providing a new avenue for sensitive bioanalysis and clinical diagnosis.

Solvothermal ion exchange preparation of Bi11VO19 to sensitize TiO2 NTs with high photoelectrochemical performances

Ag3VO4 nanograss was deposited on the surface of vertically grown TiO2 nanotube arrays (TiO2 NTs) by a successive ion layer adsorption and reaction (SILAR) method, and the Ag3VO4 nanograss was further transformed into Bi11VO19 by the solvothermal ion exchange method. The formation of Bi11VO19 was influenced by solvothermal intervals, and the TiO2 NTs/Bi11VO19 exhibited outstanding visible light response and photoelectrochemical activity. The TiO2 NTs/Bi11VO19 (3) prepared with solvothermal treatment for 3 h showed the optimal photoelectric conversion and photoelectrocatalytic (PEC) properties. The transient photocurrent density, photovoltage and charge carrier concentration achieved 9.53 mA/cm2, −0.29 V and 1.36 × 1020 cm−3, respectively. Furthermore, the PEC rate constants of TiO2 NTs/Bi11VO19 (3) for the MO, RhB and MB degradation achieved 3.56 × 10−3, 9.01 × 10−3 and 2.30 × 10−2 min−1, respectively. The PEC removal efficiency of Cr(VI) was 86.62%. The outstanding photoelectric activity drives the TiO2 NTs/Bi11VO19 photoelectrode prospective applications in waste-water purification and solar cells.

Visible/near-infrared light response VOPc/carbon nitride nanocomposites: VOPc sensitizing carbon nitride to improve photo-to-current conversion efficiency for fabricating photoelectrochemical diclofenac aptasensor

A novel photoelectrochemical (PEC) aptasensor for diclofenac detection, based on visible/near-infrared (vis/NIR) light-responsive vanadyl-phthalocyanine/graphitic carbon nitrid nanosheet (VOPc/CN) nanocomposites, was successfully fabricated. In this work, the first coupling of CN and VOPc with a facile solution–phase method was prepared and applied to PEC sensing. The UV–vis diff ;use reflection spectra (DRS) indicated that VOPc is an excellent photosensitizer when applied to the surface of CN. It promoted CN light absorption to the visible-NIR region, which greatly enhanced the light excitation capability. The PEC signal of the VOPc/CN nanocomposites improved 2.7 and 12.42-fold compared with pure VOPc and CN, respectively, indicating that VOPc/CN nanocomposites have good photoelectric activity and enhanced photo-to-current conversion efficiency. As a result, VOPc sensitized CN was introduced as a covalent immobilizing PEC aptasensor for the sensitive and selective determination of diclofenac (DCF). Under optimal conditions, the fabricated PEC biosensor exhibited good PEC performances with high sensitivity, a low detection limit of 0.03 nM (S/N = 3) and a wide linear response, in the range of 0.1-500 nM. This was due to the specific interaction between DCF and the aptamer. It is concluded that VOPc/CN nanocomposites are potentially promising photoactive materials for applications in PEC biosensors, as well as for photocatalysis and other related fields.

Poly (3, 4-ethylenedioxythiophene) modified polyvinylidene fluoride membrane for visible photoelectrocatalysis and filtration

A polyvinylidene fluoride (PVDF) organic conductive membrane with photoelectric activity was successfully developed via printing of oxidant (FeCl3·6H2O) layer by layer and then chemical vapor deposition (CVD) of Poly (3, 4-ethylenedioxythiophene) (PEDOT). Four kinds of membranes were prepared by changing the number of oxidant coatings layers. The structure and photoelectric properties of four membranes were well characterized. The photocurrent density of 3.7 × 10−4 A indicated that the four-oxidant coating layers membrane achieved the best performance in photo-electricity activity. A comprehensive study of degradation efficiency under different photoelectric conditions was carried out. Results showed that the photoelectrocatalytic removal of tetracycline hydrochloride was 1.6 and 7.9 times higher than that of photocatalysis and photolysis, respectively, under a voltage of 3 V assisted with visible light irradiation. The anti-interference and stability tests in continuous filtration process demonstrated that the dissolved organic matters (DOMs) can result in a 30% fluctuation on removal rate. The streaming potential tests of DOMs adsorption on membrane surface indicated that the more obvious the adsorption phenomenon was, the degradation of tetracycline hydrochloride was weaker. The degradation intermediates were identified and pathways were proposed in this work. The photoelectrocatalysis of PEDOT modified PVDF membrane provided a new potential for water purification.

Ag6Si2O7/CNTs with highly efficient and stable visible light photocatalytic activity

A novel Ag6Si2O7/CNTs composite photocatalyst was prepared by in-situ precipitation and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), ultraviolet-visible diffuse reflection spectroscopy (UV-vis DRS) and photoluminescence spectroscopy (PLS). Photoelectric property and photocatalytic activity were evaluated by photocurrent (PC) and methylene blue (MB) degradation. Photocatalytic activity of Ag6Si2O7/CNTs firstly increased and then decreased with the increasing CNTs content. The degradation ratio of MB by Ag6Si2O7/CNTs with the CNTs content of 0.1% attained 95.2% under visible light irradiation only for 5 min and still retained 93.8% after three recycling runs.

Oxygen vacancy enhanced photoelectrochemical performance of Bi2MoO6/B, N co-doped graphene for fabricating lincomycin aptasensor

Oxygen defect-engineered is an important strategy to improve the photoelectric activity of materials. Herein, a facile one-pot solvothermal method was utilized to synthesize visible light-responsive photoactive Bi2MoO6 nanoparticles anchored boron and nitrogen co-doped graphene (BNG) nanosheets nanocomposites with oxygen vacancy. The incorporation of BNG nanosheets increased the oxygen vacancies amounts on Bi2MoO6 remarkably, and the presences of oxygen vacancies can be beneficial to broaden the absorption range. The absorption edge of Bi2MoO6/BNG was widened from 500 nm to 550 nm compared to Bi2MoO6, and the charge transfer was accelerated to improve the photoactive of Bi2MoO6/BNG. Under visible light illumination, the photoelectrochemical (PEC) response of the as-prepared Bi2MoO6/BNG was 11.6-fold, 6.7-fold, 3.1-fold and 2.4-fold higher than that of pristine Bi2MoO6, Bi2MoO6/graphene, Bi2MoO6/nitrogen doped graphene and Bi2MoO6/boron doped graphene. Using Bi2MoO6/BNG nanocomposites with the superior PEC performance as photoactive materials in combination with specifically recognized lincomycin (LIN) aptamer, a highly efficient PEC aptasensor was successfully constructed for sensitive analysis of LIN. Under optimal conditions, the proposed PEC aptasensor exhibited excellent analytical performance for LIN with a wide linear response of 1 × 10−11 to 1 × 10−6 mol L−1 along with a low detection limit of 3.7 × 10−12 mol L−1 (defined as S/N = 3). The as-prepared Bi2MoO6/BNG nanocomposites exhibit excellent visible light response and PEC performance, indicating its potential applications in PEC biosensor.

Fabrication of CdS quantum dots sensitized TiO2 nanowires/nanotubes arrays and their photoelectrochemical properties

Herein, CdS quantum dots (QDs) sensitized TiO2 nanowires/nanotubes arrays (CdS–TiO2 NWs/NTs) have been successfully fabricated through an optimized one-step anodization method, followed by successively ion layer adsorption and reaction strategy. The structures of the as-prepared samples were characterized by scanning electrons microscopy, X-ray diffraction and X-ray photoelectron microscopy. Results indicated that TiO2 NWs/NTs were comprised of well-ordered NTs arrays in the bottom and NWs at the mouth of the NTs. CdS QDs were uniformly adhered to the surface of the NWs, as well as inner walls of the NTs. In addition, optical and photoelectronchemical properties of the as-prepared samples were investigated. All results showed that CdS–TiO2 NWs/NTs exhibited excellent photoelectric and photocatalytic activities, a photocurrent density of 1.04 mA cm−2, a photocatalytic efficiency of degradation methyl blue of 97.8% after 120 min, and the rate of repeated degradation maintained at 95.8% after 5 cycles. A possible mechanism was described to lay the foundation for future applications.

Impacts of graphene sheets on photoelectric and photocatalytic activities of SnS2 nanoparticles

Abstract Hybrid materials of SnS2 nanoparticles on graphene sheets (GS) were prepared by a facile one-step hydrothermal procedure. The as-obtained samples were characterized by X-ray diffraction (XRD), Raman spectra, UV–vis diffuse reflectance spectra (DRS), Transmission electron microscopy (TEM), photoluminescence spectra (PL) and electrochemical equipment. The effects of GS on photoabsorption range, the apparent band gap, the separation efficiency of photogenerated electron-hole pairs, and concentration of hydroxyl radicals of SnS2 were researched. The as-samples exhibited an enhanced absorption in the visible region (λ > 600 nm) with increasing the amount of graphene and the band gap was about to 2.11 eV. The photocatalytic activity of GS/SnS2 is consistent with the results of photocurrents and concentration of hydroxyl radicals and the best ratio of graphene to SnS2 is 1%. The graphene can effectively promote the separation of photo-induced carriers and thus strengthen the photocatalytic ability. Furthermore, excess graphenes will not favor the enhancement of photocatalytic activity.

Self-induced liquid crystal q-plate by photoelectric interface activation

Here, we report on the experimental demonstration that highly efficient self-induced spin-orbit optical vortex generation can be achieved by using standard liquid crystal materials and surface treatment agents. This is done by revisiting the recent attempt by Zolot'ko and coworkers to produce self-induced liquid crystal vortex plates using the dc electric field [I. A. Budagovsky, S. A. Shvetsov, and A. S. Zolot'ko, Mol. Cryst. Liq. Cryst. 637, 47 (2016)] that remains, so far, limited to moderate efficiencies. The phenomenon is the result of the self-back-action of light arising from the spontaneous creation of a liquid crystal topological defect. These results demonstrate photo-electric interface activation as a candidate towards the development of a self-adapted spin-orbit photonic toolbox, thus enabling agile management of the orbital angular momentum of light.

Effects of the Ligand Structures on the Photoelectric Activities, a Model Study Based on Titanium-Oxo Clusters Anchored with S-Heterocyclic Ligands.

Titanium oxo clusters (TOCs) have become one of the worldwide hot research topics because they are excellent molecular TiO materials having unique photoactive properties and can been used as models of dye-sensitized solar cells (DSSCs). S-Heterocyclic ligands such as thiophene (Th) and tetrathiafulvalene (TTF) derivatives have been widely used in electronic or photoelectronic devices and solar cells. However, a study of the synthesis and properties of TOCs anchored with Th and TTF derivatives is missing. Herein four such TOCs as single crystals were synthesized and structurally characterized: [Ti3O(OiPr)8(LTh)2] (1), [Ti4O2(OiPr)10(LTTF)2] (2), [Ti6O4(OiPr)10(LTh)2(O3PPh)2] (3), and [Ti6O4(OiPr)10(LTTF)2(O3PPh)2] (4). Charge transfer from the Th or TTF electron donor to the TOC core was evaluated by electronic spectra and theoretical calculations. This work first systematically investigated the photoelectrochemistry of TOCs with different conjugated S-heterocyclic ligands in molecular levels. The photocurrent densities of these cluster-modified TiO2 electrodes were examined using DSSCs, which were well responsive to irradiation. The photocurrents of TTF cluster-modified electrodes are higher than those of the Th cluster-modified electrodes because of the sulfur-rich conjugated system.

Facile and highly sensitive photoelectrochemical biosensing platform based on hierarchical architectured polydopamine/tungsten oxide nanocomposite film

The fabrication of photosensitive interface and molecular recognition layer at the biosensing surface are of vital importance in photoelectrochemical (PEC) biosensor construction. Developing facial methods with favorable biomolecule immobilization as well as excellent photoelectric activity still need to be explored. In this work, by integration of the merits of tungsten oxide (WO3) semiconductor nanomaterial and polydopamine (PDA) polymer, a novel biofunctional PDA/WO3 nanocomposites (PDA/WO3 NCs) modified ITO hierarchical architecture was fabricated by simple thermal annealing and self-polymerization methods. The proposed PEC biosensor platform based on PDA/WO3/ITO not only have preponderances in simple preparation, but also possesses excellent PEC activity, high specific surface area and good microenvironment for biomolecule immobilization. Utilizing CYFRA 21-1 as a model target, label-free PEC immunosensor was developed successfully, which exhibited great sensitivity and broad dynamic range with four orders of magnitude (10 pg mL−1 to 100 ng mL−1), and the limit of detection was as low as 2.5 pg mL−1. Moreover, owing to the great sensitivity and selectivity of the proposed platform, this convenient sensor also performed well in real serum sample analysis. It is worth noting that our work not only helps in gaining a better understanding of the applicability of the PEC properties of PDA/WO3 NCs, but also sheds novel light on the design and development of PEC biosensing platform based on PDA/WO3 NCs.

Multi-layered nanoscale cellulose/CuInS2 sandwich type thin films

A generic procedure for the manufacturing of cellulose-metal sulfide multilayered sandwich type thin films is demonstrated at the example of copper indium sulfide. These multilayers were created by alternate spin coating steps of precursors, followed by their conversion using either acidic vapors, or heat treatment. As precursors, cellulose xanthate, a widely available cellulose derivative employed in viscose fiber manufacturing and commercial copper and indium xanthates were used. After conversion of the single layers into cellulose and copper indium sulfide, the film properties (structure, thickness, photoelectric activity) of the single and multilayer systems consisting of alternate layers of cellulose and copper indium sulfide were studied. For the proof of concept, up to five layers were built up, showing a clear separation of the cellulose and the metal sulfide layers as demonstrated using cross sectional analysis using ion slope beam cutting and SEM imaging. Finally, the conversion of xanthates was performed using UV light and a mask, allowing for the creation of 2D patterns.

Tailoring sub-bandgap of CuGaS2 thin film via chromium doping by facile chemical spray pyrolysis technique

Tailoring sub-bandgaps using intermediate states or bands with wide bandgap semiconductors is a promising and novel technique for the application in high efficiency solar cells. Pure and chromium (Cr) doped chalcopyrite CuGaS2 (CGS) thin films were prepared by facile chemical spray pyrolysis technique and annealed in vacuum, nitrogen and argon atmospheres. Structural characterization confirmed that the prepared films are in tetragonal chalcopyrite structure with polycrystalline nature. No secondary phases were present in both pure and Cr doped CGS thin films. Presence of Cr ions was confirmed by X-ray photoelectron spectroscopy and energy dispersive analysis of X-rays analyses. The optical direct and sub band gap of pristine and Cr doped CGS thin films were measured from UV absorption data. It was revealed that the pure CGS film has a band gap of 2.40 eV sub-band gap values were observed at 2.25 and 2.15 eV for 1 and 2 wt% of Cr doping, respectively. These gaps can be ascribed to the formation of intermediate bands due to hybridization of Cr d-states into the host electronic structure. Meanwhile, photoconductivity study demonstrated the photo-electric activity of the intermediate bands in the Cr doped thin films.

Purification and biochemical characterization of photo-active membrane protein bacteriorhodopsin from Haloarcula marismortui, an extreme halophile from the Dead Sea

Bacteriorhodopsin (BR) is an exciting photo-active retinal protein with many potential industrial applications. In this study, BR from the extremely halophilic archaeon Haloarcula marismortui (HmBR) was purified successfully using aqueous two phase extraction method. Absorption spectroscopy analysis showed maximum absorption peak of HmBR retinal protein (λmax) at 415 nm. The purified HmBR was visualized by SDS-PAGE, with a subunit molecular mass of 27 kDa, and its identity was confirmed by resonance Raman spectroscopy, Fourier transform infrared spectroscopy and atomic force microscopy. The effect of pH and salt concentration on the absorption spectrum of HmBR was evaluated. Red-shifted in λmax of HmBR was recorded at acidic condition (pH 5) and HmBR showed remarkable optical activity under high salinity condition. The photoelectric activity of HmBR was evaluated by measuring the DC-voltage generated from HmBR coated on indium tin oxide (ITO) glass when light illumination was applied.

CdSe modified TiO2 nanotube arrays with Ag nanoparticles as electron transfer channel and plasmonic photosensitizer for enhanced photoelectrochemical water splitting

Ag nanoparticles (NPs) and a CdSe nanocrystal were successively deposited on the surface of a TiO2 nanotube array film (CdSe/Ag/TiO2 NTs) via microwave assisted chemical reduction and in situ fabrication methods. The nanotubular structure of TiO2 preserves well after loading Ag and CdSe, as the ternary composite not only exhibits an excellent visible light harvesting ability but also has the smallest charge transfer resistance according to electrochemical impedance measurement. The most positive flat band potential of CdSe/Ag/TiO2 NTs facilitates charge carrier transfer at the semiconductor-electrolyte interface. Notably, the introduction of Ag nanoparticles forms a unique carrier-transfer-channel in the CdSe/Ag/TiO2 NTs system, in which the Ag nanoparticles can take advantage of its high carriers transfer rate as a linker. In addition, Ag serving as a surface plasmon resonance source further improves photoelectric catalytic activities of the sample. It is noteworthy that CdSe/Ag/TiO2 NTs exhibits the desired photoelectrochemical performance with the highest H2 production rate of 413.99 µmol cm−2 after 2.5 h irradiation.

Label-free photoelectrochemical immunosensor for NT-proBNP detection based on La-CdS/3D ZnIn2S4/Au@ZnO sensitization structure

A new, photoelectrochemical immunosensor was proposed on the basis of the La-CdS/3D ZnIn2S4/Au@ZnO sensitization structure for detection of aminoterminal pro-brain natriuretic peptides (NT-proBNP). The Au@ZnO-modified electrode was first assembled with 3D ZnIn2S4, and then further deposited with lanthanum doped cadmium sulfide (La-CdS) via successive ionic layer adsorption and reaction strategy. The Au@ZnO has excellent photoelectric activity and electrical conductivity. The ZnIn2S4 with 3D architectures not only exhibit high photocurrent intensity under visible-light irradiation but also have large surface for the La-CdS deposition. Meanwhile, the La-CdS doped structure could depress the charge recombination, which effectively promotes separation of the generated electron-hole (e-/h+) pairs and consequently enhances the photocurrent conversion efficiency. The polydopamine (PDA) was used not only as a cross-linker reagent for the immobilization of the anti-NT-proBNP but also as an electron donor for promoting the photo-generated e-/h+ separation of the semiconductors. Under optimal conditions, the well-designed photoelectrochemical immunoassay exhibited a low detection limit of 0.32 pg mL−1 and a wide linear range from 0.8 pg mL−1 to 45 ng mL−1 for target NT-proBNP detection. Meanwhile, it also presented good reproducibility, specificity, and stability and might open a new promising strategy for the detection of other important tumor markers.

Current Advances in Semiconductor Nanomaterial-Based Photoelectrochemical Biosensing.

Photoelectrochemical (PEC) analysis is a new detection technique developed in recent years, which has the advantages of high sensitivity, low background signal and desirable selectivity, obtaining the great progress in sensing applications. Semiconductor nanomaterials with excellent photoelectric activity have played a vital role in the construction of PEC sensing platform. Thus, this Review introduces the recent advances of semiconductor nanomaterials-based PEC analysis, and describes the typical PEC sensing strategies. Some representative nanomaterials, including metallic oxides, metallic sulfides, graphitic carbon nitride, transition-metal dichalcogenides and quantum dots, are summarized for advanced PEC devices, as well as their applications in nucleic acid analysis, immunoassays, cell detection, protein and enzyme sensing, and small biomolecule monitoring. Finally, some future opportunities and challenges of PEC biosensing are also discussed.