Utilization Efficiency Of Visible Light Research Articles

N-Cdots-decorated TiO2(B)/anatase microspheres with high photocatalytic performance in visible light

Nitrogen-doped carbon dots (N-Cdots) with enhanced absorption in visible light region were combined with TiO2(B)/anatase (TiO2(A + B)) microspheres consist of nanosheets via a one-step synthesis. The successful connection of N-Cdots and TiO2 substrate was confirmed by the appearance of new Ti–O–C bond. The degradation rate of Rhodamine B (RhB) for N-Cdots@TiO2(B)/anatase was improved to seven times higher than that of initial TiO2(B) microspheres under full spectrum illumination. N-Cdots@TiO2(B)/anatase photocatalyst also exhibited high photocatalytic ability under visible light irradiation. The possible mechanism was proposed in two irradiation conditions. N-Cdots act as a semiconductor to generate electrons and holes. The electrons were transferred to the conduction band of TiO2(B) and anatase, which improved the visible light utilization efficiency. Meanwhile, the heterophase structure of TiO2(A + B) substrate restrained the recombination of electron-hole pairs. It is the synergistic effect of heterophase and N-Cdots that enhanced the photocatalytic performance.

Fabrication of multilayer porous structured TiO2–ZrTiO4–SiO2 heterostructure towards enhanced photo-degradation activities

Multilayer porous structured TiO2–ZrTiO4–SiO2 photocatalyst with built-in TiO2/ZrTiO4 heterojunction and oxygen vacancies was synthesized by sol-gel method combined with template method using colloidal polystyrene spheres as templates. Results show that the multilayer porous structure can be fabricated by controlling the calcination system and the amount of template, and the fabrication of which can also contribute to the generation of oxygen vacancies by creating an anoxic environment. During the photodegradation process, high efficiency of visible light utilization can be achieved due to the slow photon effect of the multilayer porous structure, which can also increase the probability of the contact between Rhodamine B (RhB) with the active sites of the catalyst. Also, the synergistic effect of the generated TiO2/ZrTiO4 heterojunction and built-in oxygen vacancy defects jointly promoted the separation of photogenerated carriers. Thus excellent adsorption rate (75.6%, 60 min) and photodegradation rate (95%, 90 min) of the catalyst were obtained. Furthermore, the up-shifted conduction band and valence band maximum positions are beneficial for the mobility of photogenerated holes and inhibit their reaction with H2O to generate ·OH, while the photogenerated electrons can react with O2 to form ·O2−, resulting that the holes and ·O2− participated in the photodegradation of RhB over the as-prepared catalyst.

1D/2D MnWO4 nanorods anchored on g-C3N4 nanosheets for enhanced photocatalytic degradation ofloxacin under visible light irradiation

Herein, MnWO4 nanorods coupled with g-C3N4 nanosheets were fabricated by a simple hydrothermal method, followed by an ultrasonication method. Morphological features, chemical composition, optical properties and crystallographic information of the prepared materials were obtained using SEM-EDX, TEM, XRD, XPS, FT-IR, UV–vis DRS, and PL techniques. The synthesized MnWO4@g-C3N4 nanocomposite displayed excellent photocatalytic activity towards ofloxacin (OFX) under visible light irradiation. Moreover, the influence of reaction parameters such as the catalyst dosage, pollutant concentration and presence of inorganic anions (Cl−, CO32− and SO42−), was investigated during the photocatalytic process. Notably, among the inorganic anions, SO42− and CO32− significantly hampered OFX degradation, while Cl− ions showed minimal effect on the degradation process. The apparent rate constant for MnWO4@g-C3N4 from first order kinetics was 3.5 and 4.8 times higher than that of pure g-C3N4 and MnWO4, respectively. Based on the obtained results, the possible charge transfer mechanism was proposed. The enhanced photocatalytic performance of the binary nanocomposite could be ascribed to the synergistic effect between MnWO4 nanorods and g-C3N4 nanosheets resulting in efficient visible light utilization and inhibition of the charge carrier recombination. This work demonstrates the potential application of MnWO4@g-C3N4 nanostructures in the photocatalytic removal of emerging pollutants in water.

Fabrication of Ag based ternary nanocomposite system for visible-light photocatalytic hydrogen evolution reaction

Solar driven visible photocatalytic H2 evolution using semiconductors is recognized as one of the most promising routes for clean energy technology; however, efficient visible light utilization and charge separation are the key roles in a photocatalyst system for high activity. Herein, Ag based ternary nanocomposite system, Ag2S/Ag/Ag3VO4 was synthesized by chemical reduction and subsequent hydrothermal methods. The prepared nanocomposites were characterized by Powder X-ray diffraction, X-ray photoelectron spectroscopy, Scanning and transmission electron microscopy, UV–vis diffuse reflectance and photoluminescence spectroscopy methods. The Ag2S/Ag/Ag3VO4 ternary nanocomposite system displayed a higher photocatalytic H2 evolution activity than that of pure Ag3VO4, Ag2S and their binary composites under visible light irradiation. In the present work, Ag2S/Ag/Ag3VO4 exhibited a photocatalytic H2 evolution activity of ~8.5 mmol·g−1. The enhanced photocatalytic activity can be attributed to the improved visible light absorption and effective charge separation between Ag3VO4 and Ag2S via the electron shuttle mediator Ag.

Sol-gel derived Al and Ga co-doped ZnO nanoparticles: Structural, morphological and optical investigation

A sequence of Aluminum and Gallium co-doped ZnO nanoparticles (AGZ NPs) were synthesized by sol-gel method. The structural and morphological characteristics were explored by the advanced means of X-ray diffractometer (XRD) and transmission electron microscope (TEM), and the optical and photoluminescence properties were evaluated via UV–visible spectrophotometer and photoluminescence (PL), respectively. The AGZ NPs formed during the thermal treatment process exhibit well hexagonal wurtzite structure and slight (101) preferred orientation growth, the average sizes calculated from XRD are in the ranges from 23.9 to 32.4 nm which is corroborated well with TEM. The spherical and rod-shaped morphology of the resulted samples are authenticated by TEM analysis. UV–vis absorption spectra results indicate the introduction of Ga3+ is beneficial to the optical absorption property and the utilization efficiency of visible light. The optical energy band gap shows the initial decrease under low Ga concentration which increases further with increasing of Ga concentration. The exported PL spectra shows four fluorescence emission peaks attributed to the different intrinsic properties and defects therein. Simultaneously, AGZ2 suggests a minimum recombination rate of e−/h+ pairs while the temperate Al/Ga co-doping proportion gives rise to finer crystallite dimension, lower optical energy band gap and lower recombination rate of e−/h+ pairs.

Influence of annealing temperature on microstructure and photoelectric properties of ternary CdSe@CdS@TiO2 core–shell heterojunctions

CdSe@CdS@TiO2 microsheet array (MSA) ternary core–shell heterojunctions were prepared by successive electrodeposition of CdS and CdSe onto TiO2 microsheets using cyclic voltammetry. The photoelectrochemical performance of CdSe@CdS@TiO2 MSAs ternary core–shell heterojunctions is significantly improved. This structure not only greatly enhances the utilization efficiency of visible light but also greatly extends the spatial separation of photoinduced charge. This is because CdSe@CdS@TiO2 MSAs ternary core–shell heterojunctions have an inherent cascade energy band structure and a high-quality contact between each other at the interface. After annealing, CdSe@CdS@TiO2 MSAs ternary core–shell heterojunctions show a further improved photoelectrochemical performance because the formation of ternary compound CdS1−xSex enhances the quality of the contact interface between CdSe and CdS layers and consequently increases the transportation efficiency of photoinduced charges and injection efficiency of photoinduced electrons to the TiO2 layer. The maximum photocurrent density of 3.5 mA/cm2 was observed in the CdSe@CdS@TiO2 MSAs ternary core–shell heterojunctions after annealing at 350 °C, which is 9.46, 3.18 and 2 times higher than that observed in CdS@TiO2 MSA, CdSe@TiO2 MSA, and as-prepared CdSe@CdS@TiO2 MSA photoelectrodes, respectively.

Z-Scheme Ag3PO4/g-C3N4 Nanocomposites for Robust Cocatalyst-Free Photocatalytic H2 Evolution Under Visible Light Irradiation

Ag3PO4/g-C3N4 nanocomposite photocatalysts were synthesized by calcining the mixture of urea and trace amount of Ag3PO4 microcrystals at 600 °C, in which Ag3PO4 nanoparticles with size of 20–30 nm were wrapped with g-C3N4 layers. The obtained Ag3PO4/g-C3N4 composites exhibited efficient utilization of visible light and separation of photoinduced electron–hole pairs, resulting in enhanced photocatalytic activity for H2 evolution. The optimum photocatalytic H2 evolution rate under visible light without Pt co-catalyst for 0.04AP-CN composite was 89.4 µmol/h, which is 3.34 times of that of g-C3N4 (26.7 µmol/h). The H2 evolution rate for 0.04AP-CN with 3 wt% Pt co-catalyst was up to 273.6 µmol/h, which is 2.39 times of that g-C3N4 (114.4 µmol/h). The performance of Ag3PO4/g-C3N4 composite was enhanced significantly due to the synergistic effect of the interface formed between Ag3PO4 and g-C3N4.

Heterojunction Tuning and Catalytic Efficiency of g-C3N4–Cu2O with Glutamate

The g-C3N4–Cu2O (CNCu2O-G) with a p-n heterojunction structure in the presence of glutamate was successfully developed through hydrothermal synthesis and high-temperature calcination. When addition the glutamate, the surface morphology of the heterojunction was regulated, and its specific surface area increased by a factor of approximately 1.5, and reaction sites were increased. Additionally, the charge recombination rate of the heterojunction was reduced, and the absorption band was red-shifted to 460 nm, leading to stronger heterostructure contact interfaces, thus the visible-light utilization efficiency was enhanced. The catalytic performance of the CNCu2O-G was very stable, with no significant change in the photocatalytic efficiency of CNCu2O-G after six recycles, the Fourier transform infrared patterns and X-ray diffraction of CNCu2O-G exhibited no significant changes after the photocatalytic reaction. Furthermore, electron paramagnetic resonance and free-radical removal experiments indicated that th...

Effects of N Doping on the Microstructures and Optical Properties of TiO2

TiO2 nanopowders with different nitrogen (N) dopant concentrations were first synthesized by sol-gel method. XRD, TEM, HRTEM, XPS, UV-vis DRS were used to characterize the effects of N doping on the microstructures and optical properties of TiO2. The results indicated that the prepared TiO2 only contained anatase phase with a slight distortion, and the N doping improved the dispersity of TiO2. The N doping leaded to more defects in TiO2, capturing the charge carriers and inhibiting the combination of electrons and holes. Also, the N-doped TiO2 was composed of Ti, O and N. Further, N was doped into the TiO2 lattice by substituting for O, forming the oxidized nitrogen in the form of Ti–N–O or Ti–O–N bond, and Ti was present in the form of Ti4+ in TiO2. Finally, the absorbance of N-doped TiO2 was obviously improved in both UV and visible light region. Optical absorption edges of N-doped TiO2 samples showed obvious red shift, which expanded spectral absorption range of TiO2 and improved the utilization efficiency of visible light. It is concluded that N element was successfully doped into TiO2 crystal lattice, and the N dopant concentration of 3.0% was designed to modify TiO2.

Carbon Dots/CoFe2O4 Mesoporous Nanosphere Composites As a Magnetically Separable Visible Light Photocatalyst

Carbon dots (CDs)/CoFe2O4 mesporous nanosphere composites were prepared. In comparison with CoFe2O4, the CDs/CoFe2O4 composites exhibited the enhanced photocatalytic activity in the degradation of methylene blue (MB) in the presence of H2O2 under the visible light irradiation. Specifically, the degradation rate attained using the CDs(4 wt %)/CoFe2O4 composite was about 3.65 times higher than that with neat CoFe2O4. Moreover, the CoFe2O4 paramagnetic nanospheres allowed facile repeatable use of CDs/CoFe2O4 composites after magnetic separation. After five runs, the reduction of degradation rate was less than 5%, reflecting favorable photostability and magnetic separability of CDs/CoFe2O4 composites. The CDs not only enhanced visible light utilization efficiency of CoFe2O4 due to up-conversion photoluminesence, but also promoted the transfer and separation of electron-hole pairs as a result of their outstanding charge transfer characteristics, which collectively accelerate the generation of reactive species (such as • $${\text{O}}_{2}^{ - }$$ , •OH, and h+) in the presence of H2O2.

Hydrogen peroxide-assisted synthesis of oxygen-doped carbon nitride nanorods for enhanced photocatalytic hydrogen evolution.

Polymer-derived carbon nitrides based photocatalysts are very promising for solar water splitting, CO2 reduction and environmental remediation. However, these photocatalysts still suffer from low visible light utilization efficiency, rapid recombination of photogenerated charge carriers and slow transfer kinetics. Herein, we report a hydrogen peroxide-assisted hydrothermal strategy to synthesize one-dimensional oxygen-doped carbon nitrides (OCN) for photocatalytic hydrogen evolution. A possible self-assembly mechanism is discussed. Experimental results and theoretical calculations indicate that the as-synthesized one-dimensional OCN possess narrowed band gap energy and optimized band structure, which may allow more effective visible-light harvesting and facilitate photogenerated electron–hole pair separation and transfer. As a result, the photocatalytic hydrogen evolution rates improve from 10.4 μmol h−1 to 74.0 μmol h−1 under visible light (λ > 400 nm), which is among the best of the reported CN-based photocatalysts for visible-light-driven hydrogen evolution. This study provides a new avenue toward the development of highly efficient carbon nitrides based photocatalysts for photocatalytic applications.

Polydopamine-Inspired Design and Synthesis of Visible-Light-Driven Ag NPs@C@elongated TiO2 NTs Core–Shell Nanocomposites for Sustainable Hydrogen Generation

The primary challenge of photocatalytic hydrogen generation is to exploit a catalyst with good durability and low cost. Here, we designed a facile and efficient process of loading silver nanoparticles (Ag NPs) in situ on the core–shell nanocomposite of the elongated titanium dioxide nanotubes with a carbon layer (C@TiO2 NTs) by polydopamine (PDA) without addition of any binder. The combination of C@TiO2 NTs with Ag NPs has excellent performance toward photocatalytic hydrogen production and degradation of rhodamine B (RhB) under visible light irradiation. The characterizations (SEM, TAM, XRD, XPS, etc.) showed that the carbon layer on nanotubes could conformably cover the whole of TiO2 NTs to form the core–shell structure, which not only prevented Ag NPs from aggregating but also acted as the electronic transport channel. Meanwhile, Ag NPs were uniformly distributed on the surface of C@TiO2 NTs. In conclusion, under the synergistic effect of Ag nanoparticles and the outer-carbon layer, the utilization efficiency of visible light has been enhanced, and the recombination of electrons/holes has been suppressed for Ag@C@TiO2 NTs nanocomposites. Therefore, the degradation efficiency of RhB and hydrogen generation rate are 2.5 times and 4.8 times higher than those of the pure TiO2 NTs, respectively. This work may provide fruitful experience for developing a novel strategy into the design and fabrication of stable and highly active visible-light catalysts with noble metal modification toward sustainable hydrogen production in the energy filed.

Perovskite-type BiFeO3/ultrathin graphite-like carbon nitride nanosheets p-n heterojunction: Boosted visible-light-driven photoelectrochemical activity for fabricating ampicillin aptasensor

Developing effective sensing method for trace analysis of ampicillin (AMP) is urgent and significant due to its residue possess serious threats to human health. Herein, a p-n heterojunction, on the basis of p-type BiFeO3 nanoparticles coupled n-typed ultrathin graphite-like carbon nitride (utg-C3N4) nanosheets, has been designed and synthesized via a simple electrostatic interaction strategy. Such p-n heterojunction has two advantages: one is capable to narrow the band gap of photoactive materials from 2.20 eV of BiFeO3 down to 2.04 eV of BiFeO3/utg-C3N4, leading to improve the efficiency of visible light utilization; and the other is to facilitate the charge separation rate, resulting in the boosted photoelectrochemical (PEC) performance of BiFeO3/utg-C3N4. Under visible light illumination, the photocurrent of the resulted BiFeO3/utg-C3N4 was 7.0-fold enhanced than that of pure BiFeO3 nanoparticles, and indeed 2.3-fold enhanced comparing to BiFeO3/bulk-C3N4. Based on excellent PEC properties of BiFeO3/utg-C3N4, an on-off-on PEC aptasensor was successfully fabricated for ampicillin (AMP) determination with highly selectivity and sensitivity. The fabricated PEC aptasensor exhibited excellent PEC performance with a broad linear in the range from 1 × 10–12 mol L–1 to 1 × 10−6 mol L–1 as well as a low detection limit of 3.3 × 10–13 mol L–1 (S/N = 3), and also good feasibility in real sample. The excellent analytical performance indicated that PEC aptasensor on the basis of the visible light driven BiFeO3/utg-C3N4 heterojunction can provide a promising biosensor platform for sensitive detection AMP in food and environment analysis.

Spontaneous Redox Approach to the Self-Assembly Synthesis of Au/CeO2 Plasmonic Photocatalysts with Rich Oxygen Vacancies for Selective Photocatalytic Conversion of Alcohols.

We present the self-assembly synthesis of core-shell structure Au/CeO2 composites with different Au loadings through a spontaneous chemical redox approach at an ambient temperature utilizing HAuCl4 and Ce(NO3)3 as reaction substrates in an alkaline environment. The results demonstrate that the as-synthesized Au/CeO2 composites exhibit spherical shape morphologies with porous structures, composed of Au nanoparticle (∼10 nm) cores and CeO2 nanoparticle shells with abundant oxygen vacancies. The introduction of Au nanoparticles in CeO2 not only effectively improves the visible light utilization efficiency but also provides rich surface catalytic active sites for highly efficient visible light photocatalysis. As visible light photocatalysts (λ > 400 nm), the as-synthesized Au/CeO2 composites with the Au loading amount ≥4.0 wt % exhibit high conversion and selectivity (∼100%) of benzyl alcohol to benzaldehyde under the given experimental conditions. Moreover, Au/CeO2 also shows a general applicability as a visible light photocatalyst for the selective oxidation of other alcohols to corresponding aldehydes or ketones. The photocatalytic mechanism studies indicate that the photoelectrons/holes produced from the photoexcited Au and the formed superoxide radicals in the oxygen vacancies of CeO2 synergistically contribute to the high performance of the selective photocatalytic oxidation of alcohols to aldehydes or ketones.

Environment-friendly Ag/CDots/g-C3N4 photocatalysts: Remarkably enhanced photocatalytic tetracycline degradation in visible light

The g-C3N4 was widely used in water purification recently. However, the further application was severely suppressed because of the rapid electron-hole recombination and low visible-light utilization efficiency. Herein, we fabricated the three-component Ag/CDots/g-C3N4 nanocomposites which effectively enhanced the photodegradation of tetracycline (TC) under visible light irritation (～93.4% in 60 min), compared with Ag/g-C3N4 (∼76.1%), CDots/g-C3N4 (∼63.8%) and g-C3N4 (∼44.2%). The morphology, structural and compositional information of Ag/CDots/g-C3N4 was observed as well as the optical and electric properties, and the photocatalytic mechanism was revealed in detail. The addition of CDots could effectively increase light absorption efficiency, accelerate electron transfer and separation, and act as an electron-reservoir center. The presence of Ag had increased electron density via SPR effect, further enhancing the photocatalytic performance. The Ag/CDots/g-C3N4 also showed great stability and reusability with ignorable change in five recycle. Besides, the toxicity assessment proved the good biocompatibility and low cytotoxicity of Ag/CDots/g-C3N4. The study indicated that the successful synthesis of Ag/CDots/g-C3N4 paved way to water purification.

H-doped TiO2-x prepared with MgH2 for highly efficient solar-driven hydrogen production

Efficient utilization of visible light with high stability remains a critical challenge for solar-driven photochemical generation of hydrogen (H2) using particulate photocatalysts. Black TiO2 was introduced with remarkable enhancement of visible light absorption, but its efficiency in the visible light has not reached the desired level for real-world applications. Here we report a gold-colored H-doped TiO2-x (H:TiO2-x) nanoparticles prepared by controlled reduction via simultaneous presence of [Mg] and [H], which are obtained from the decomposition of MgH2. The H-doped TiO2-x exhibits a significant activity (16.1 mmolg−1h−1) and remarkable stability after Pt deposition for solar-driven H2 generation from methanol-water. The excellent photoactivity of H-doped TiO2 can be attributed to oxygen vacancies and H doping at the reduced TiO2-x surface generated by [Mg] and [H]. The H-doped TiO2 is also producing H2 from methanol-seawater with a rate of 6.1 mmolg−1h−1 under simulated sunlight.

Pt supported and carbon coated Bi2MoO6 composite for enhanced 2,4–dibromophenol degradation under visible–light irradiation: Insight into band gap structure and photocatalytic mechanism

This study aims to reveal the visible–light photocatalytic performance of Pt supported and carbon coated Bi2MoO6 (Pt/C@Bi2MoO6) composite on the degradation of aquatic 2,4–dibromophenol (DBP) pollutant. The surface structure analysis shows that Pt and carbon layer can tightly bind to the surface of Bi2MoO6 with the chemical bonds, and hybrid the original band gap to generate new impurity levels to enhance the visible–light utilization efficiency. The carbon layer has excellent conductivity to transformation electrons from valence band (VB) site, and the supported Pt atoms on carbon layer generate a plasma electron field to enhance the reductive activity on conduction band (CB) site. The Pt/C@Bi2MoO6 composite shows more efficient and reliable abilities in DBP photocatalytic degradation, and the debromination and oxidization processes are performed separately on CB and VB site, respectively. The DBP debromination proceeds by electrons in the CB site in priority to generate non–brominated intermediate products, and then the oxidization and mineralization procedures start by hydroxide radicals in the VB site to finish the complete degradation of DBP. This research reveals the important roles of Pt and carbon layer in band gap structure modification and photocatalytic activity improvement, exhibiting a new insight to design an efficient and stable photocatalyst for persistent organic pollutant degradation under visible–light irradiation.

Co/Mn co-doped TiO2 nanotube arrays for enhanced photoelectrochemical properties: experimental and DFT investigations

In this study, we used first principle calculations to investigate the electronic properties of TiO2 modified with eight different elements. Co/Mn co-doped TiO2 nanotube arrays, which had the smallest band gap, were subsequently prepared using electrochemical anodization followed by atomic force microscopy (AFM) and field emission scanning electron microscopy (FE-SEM) measurements. The results showed that the TiO2 nanotube arrays were highly ordered and well aligned. Finally, the photoconversion efficiency was measured using photoelectrochemical experiments and, under the same conditions, the photoconversion efficiency under visible light increased approximately three times from 9.35% for the undoped TiO2 nanotubes to 21.25% for the Co/Mn co-doped TiO2 nanotubes. These results indicate that Co/Mn co-doped TiO2 nanotube arrays can improve the efficiency of visible-light utilization and could be a promising material in such fields as photocatalysis and solar cells.

Facile one-pot synthesis of visible light-responsive BiPO4/nitrogen doped graphene hydrogel for fabricating label-free photoelectrochemical tetracycline aptasensor

It is fundamental to develop highly efficient visible light-responsive photoelectrochemical (PEC) performance material for fabricating PEC biosensor. Herein, BiPO4/three-dimensional nitrogen doped graphene hydrogel (3DNGH) nanocomposites were prepared for the first time via a facile one-pot hydrothermal route. In this nanoarchitecture, the BiPO4 nanorods were anchored onto the porous structure of 3DNGH. Compared with pristine BiPO4, the absorption of BiPO4/3DNGH has been extend to visible-light region, and the energy band gap of BiPO4/3DNGH was calculated to be 2.10 eV, which was greatly narrower than that of pristine BiPO4 with a band gap of 3.85 eV. Under visible light irradiation, the photocurrent signal of the as-prepared BiPO4/3DNGH was 847.2-fold, 4.1-fold and 2.3-fold enhanced comparing to pristine BiPO4, BiPO4 functionalized reduced graphene oxide and BiPO4/nitrogen doped graphene. The enhancement of such photocurrent signal was attributed to the introduction of 3DNGH, which was capable to improve the charge transfer rate and also the efficiency of visible-light utilization of BiPO4. Based on the excellent PEC properties of BiPO4/3DNGH, a label-free PEC aptasensor for selectivity and sensitivity detection of tetracycline (Tc) was successfully established by using Tc aptamer as a biorecognition element. Under optimized conditions, the proposed PEC aptasensor exhibited a wide linear in the range from 0.1 nmol L−1 to 1 μmol L−1 as well as a low detection limit of 0.033 nmol L−1 (S/N = 3). The prepared BiPO4/3DNGH nanocomposites would serve as a promising visible light-responsive photoactive material for fabrication of PEC biosensors with high performance.

A sensitive signal-on photoelectrochemical sensor for tetracycline determination using visible-light-driven flower-like CN/BiOBr composites

As a broad-spectrum antibiotic, tetracycline (TC) is widely used in agricultural purposes and human therapy. More attention is paid to TC as a serious threat to human health, including the fast spreading of antibiotic resistance gene and the serious toxicity to aquatic organisms. Therefore, the timely and accurate determination of TC residues is an urgent task to protect the safety of human. Herein, an effective and facile photoelectrochemical sensor platform based on carbon nitride/bismuth oxyhalide (CN/BiOBr) composites can be constructed for monitoring TC. The flower-like CN/BiOBr composites are prepared via a simple one-pot ethylene glycol-assisted solvothermal process with the addition of ionic liquid 1-hexadecyl-3-methylimidazolium bromide ([C16mim]Br). In view of matched energy band positions of CN and BiOBr, the addition of CN can reduce the recombination of photogenerated electron-hole pairs and improve the efficiency of visible light utilization, leading to enhancing photoelectrochemical response of BiOBr. Under light excitation, the photocurrent of CN/BiOBr composites is drastically improved, which is 6 times as much as that of pure BiOBr. Considering the superior photoelectrochemical performance, a photoelectrochemical sensor for monitoring TC has been developed, displaying linearly enhanced photocurrent with increasing the TC concentration. Two linear relationships received are from 8.0 to 4.0 × 102 ng mL−1, and 4.0 × 102 to 5.2 × 103 ng mL−1, respectively. The detection limit is 3.8 ng mL−1. The photoelectrochemical sensor exhibits a series of benefits including excellent stability, a wide linear range, a low detection limit and good anti-interference ability. Therefore, this work may offer great promises in providing a universal and efficient photoelectrochemical sensor for the tetracycline detection, and pave the way of constructing more materials used in photoelectrochemical detection field.