Pengcheng Yan

Graphitic carbon nitride/BiOCl composites for sensitive photoelectrochemical detection of ciprofloxacin

Ciprofloxacin, as a second generation of fluoroquinolone antibiotics, has been proved to cause environmental harm and exhibits toxic effects on the wastewater and surface water even at low concentrations due to their continuous input and persistence. Despite tremendous efforts, developing ciprofloxacin detection method with accuracy and sensitivity at low-cost remains a great challenge. Herein, graphitic carbon nitride/BiOCl composite (g-CN/BiOCl) has been designed for a facile and sensitive photoelectrochemical (PEC) monitoring platform of ciprofloxacin at first time. BiOCl can be modified with the g-CN nanosheets which are obtained via solvothermal process at low-temperature conditions. The use of g-CN is shown to strongly enhance the PEC response of BiOCl due to the formation of heterojunctions. The photocurrent generated at the g-CN/BiOCl-modified ITO (with 13wt%g-CN content) is much higher and more stable than that of a BiOCl-modified ITO. Based on these findings, the g-CN/BiOCl-modified ITO was used to design a PEC assay for the antibiotic ciprofloxacin. Furthermore, the limit of detection of the ciprofloxacin PEC sensor has been significantly lowered to 0.2ngmL(-1). In addition, the PEC sensor can detect ciprofloxacin in the wide range of 0.5-1840ngmL(-1).

Photoelectrochemical sensing of 4-chlorophenol based on Au/BiOCl nanocomposites.

The Au/BiOCl composites have been prepared by a facile one-pot ethylene glycol (EG) assisted solvothermal reaction in the presence of ionic liquid 1-hexadecyl-3-methylimidazolium chloride ([C16mim]Cl). During the synthesis procedure, the [C16mim]Cl has been used as Cl source, solvent of this system, and dispersing agent to effectively disperse Au on the surface of BiOCl. The as-prepared samples have been systematically characterized by multiple instruments to investigate the structure, morphology, and photoelectrochemical properties. According to the photoelectrochemical data, the Au/BiOCl composites exhibit better photoelectrochemical performance toward the detection of 4-chlorophenol than that of the pure BiOCl. The photocurrent response of Au/BiOCl modified electrode is high and stable under light irradiation. The proposed Au/BiOCl modified electrode shows a wide linear response ranging from 0.16 to 20mgL(-1) with detection limit of 0.05mgL(-1). It indicates a dramatically promising application of bismuth oxyhalides in photoelectrochemical detection. It will be expected that the present study may be lightly extended to the monitor of other organic pollutants by photoelectrochemical detection of the Au/BiOCl composites.

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.

Photoelectrochemical sensing of bisphenol a based on graphitic carbon nitride/bismuth oxyiodine composites

Graphitic carbon nitride/bismuth oxyiodine (g-CN/BiOI) composites with excellent photoelectrochemical (PEC) performance have been designed for a facile and sensitive PEC monitoring platform of bisphenol A (BPA) for the first time. The g-CN/BiOI composites were synthesized by a facile microwave method with 1-butyl-3-methylimidazolium iodine ([Bmim]I) as precursor. The heterojunction comprising g-CN and BiOI has been fabricated. The internal electric field formed at the interface of the heterojunction contributed to the separation of photogenerated electron–hole pairs. Consequently, the g-CN/BiOI composites achieved a greatly improved photocurrent density (∼2-fold) compared to the pure BiOI. In addition, the photocurrent of g-CN/BiOI composites can be further enhanced by introducing BPA into the aqueous solution. The increased photocurrent was applied as the PEC detection signal to trace the concentration of BPA sensitively and effectively. The self-constructed BPA PEC sensor displayed a satisfactory sensing performance with a rapid response, a wide linear range (80–3200 ng mL−1) and a low detection limitation (26 ng mL−1, S/N = 3). Moreover, the BPA PEC sensor exhibited an agreeable anti-interference capacity and outstanding stability, and provided a promising analytical method to detect BPA in the environment.

Exploitation of a photoelectrochemical sensing platform for catechol quantitative determination using BiPO4 nanocrystals/BiOI heterojunction

A photoelectrochemical catechol sensor using BiPO4 nanocrystals/BiOI (BiPO4/BiOI) heterojunction is developed. BiPO4/BiOI heterojunction is fabricated via a simple one-step solvothermal method with KI and ionic liquid 1-octyl-3-methylimidazolium dihydrogen phosphate ([Omim]H2PO4). An enhanced photoelectrochemical separation efficiency is obtained due to the synergistic effect between the formation of BiPO4/BiOI heterojunction and shortening the transmission path of the electron to the surface caused by BiPO4 nanocrystals. Owing to the outstanding photoelectrochemical response of BiPO4/BiOI heterojunction to catechol, a photoelectrochemical sensor is constructed for monitoring catechol. The proposed sensor possesses reliable stability, anti-interference ability and a low detection limit with 2 ng mL-1. The linear range is from 6 to 1.20 × 104 ng mL-1. Notably, this work not only supplies a facile method for BiPO4 nanocrystals based binary heterojunction, but also helps to understand the relationship between BiPO4 nanocrystals and photoelectrochemical performance of binary heterojunction. Convincingly, this strategy can be extended to other BiPO4 nanocrystals based heterojunction and photoelectrochemical sensor platform associated with photoactive materials.