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Signal amplification strategies are of great interest in photoelectrochemical (PEC) sensing research. Herein, we explored a novel approach whereby hole transfer was accelerated from the photosensitive material Blue-TiO 2 (B-TiO 2) to the hole mediator N-hydroxyphthalimide (NHPI). Simultaneously, the introduction of the organic molecule NHPI can promote the efficiency of visible light absorption and expand the absorption range of B-TiO 2. Under visible light irradiation, the photocurrent value of NHPI/B-TiO 2 is 2.7-fold larger than that of B-TiO 2 , which can be ascribed to the acceleration of hole transfer by NHPI. More specifically, NHPI acts as a hole mediator, which effectively transfers photo-generated holes from the valence band (VB) of B-TiO 2 to NHPI. NHPI can be oxidized to phthalimide-N-oxyl radical (PINO*), thereby causing inhibition of photo-generated carrier recombination and enhancement of the photocurrent. Furthermore, a PEC aptasensor for the sensitive detection of diazinon (DIA) was constructed by combining specific aptamers on an NHPI/B-TiO 2 nanocomposite surface. The oxidation product of NHPI, PINO*, oxidizes the DIA captured by the aptamer. Under optimized experimental conditions, the linear range for DIA detection was 0.1–1000 nM, and the detection limit of the NHPI/B-TiO 2 nanocomposite aptamer sensing was 0.03 nM (S/N = 3). Therefore, this proposed method involving the hole mediator can be used as a new strategy to improve the performance of PEC. [Display omitted] • A new strategy for enhancing photoelectrochemical (PEC) signals was developed. • Hole mediator can accelerate photo-generated holes transfer. • Hole mediator can be oxidized by photo-generated holes and promote redox reaction. • Organic molecule have the advantage of high visible light absorption efficiency. • The PEC aptasensor exhibited excellent selectivity and sensitivity for Diazinon. [ABSTRACT FROM AUTHOR]

Synopsis: Diagram of one-step synthesis of core-shell LaFeO 3 @g-C 3 N 4 heterostructure and photoelectrochemical and optical absorption properties of various materials. • The LaFeO 3 @g-C 3 N 4 heterostructure was synthesized by facile one-step method. • The LaFeO 3 @g-C 3 N 4 showed superior PEC properties than LaFeO 3 /g-C 3 N 4. • A PEC aptasensor was constructed for detection of streptomycin. • The proposed aptasensor has a wide linear range and low detection limits. The development of core-shell heterostructure photoactive materials with high visible light response and charge separation efficiency is of great significance. Herein, we prepared LaFeO 3 @g-C 3 N 4 p-n heterojunction with core-shell structure by using facile one-step method. As a contrast, g-C 3 N 4 nanosheets decorated with LaFeO 3 nanoparticles (LaFeO 3 /g-C 3 N 4) were synthesized by a reported method. The LaFeO 3 @g-C 3 N 4 heterostructure boosted the visible light response and effectively separated charge carriers compared to LaFeO 3 /g-C 3 N 4. Moreover, for LaFeO 3 @g-C 3 N 4 heterostructure, the interaction of core-shell interface and synergistic effect of p-n heterojunction made photoelectrochemical (PEC) properties more stable and excellent. Concretely, the absorption band edge of LaFeO 3 @g-C 3 N 4 heterostructure was about 700 nm, which was wider than LaFeO 3 /g-C 3 N 4. Additionally, the photocurrent signal of LaFeO 3 @g-C 3 N 4 heterostructure was 2.3-fold higher than that of LaFeO 3 /g-C 3 N 4. Thus, on the basis of the prominent PEC performance of LaFeO 3 @g-C 3 N 4 heterostructure, we constructed a PEC aptasensor to detect streptomycin (STR) sensitively and selectively. The aptasensor revealed a wide linear concentration range from 0.01 nM to 10000 nM of STR, with a low detection limit of 0.0033 nM (S/N = 3). The fabricated aptasensor had excellent stability, practicability, and reproducibility, laying a good foundation for STR detection in other analytical fields. [ABSTRACT FROM AUTHOR]

Developing a simple, rapid detection method for the analysis of edifenphos (EDI) is crucial due to its residue is harmful to acetylcholinesterase on the human cellular system, and cause a lot of complications. Herein, we synthesized visible light-responsive MoS 2 nanosheets decorated with Zinc phthalocyanine (ZnPc) nanoparticles (ZnPc/n-MoS 2). Due to the sensitization of ZnPc nanoparticles, the resulting ZnPc/n-MoS 2 exhibited narrower energy bandgap and efficient charge transfer. Especially, the carrier lifetime of ZnPc/n-MoS 2 is 2 more times longer than n-MoS 2 , and the photocurrent intensity of ZnPc/n-MoS 2 is 24 times of n-MoS 2 and 22 times of ZnPc nanoparticles under visible light irradiation. Further, a visible light-responsive ultrasensitive photoelectrochemical (PEC) aptasensor for selectivity recognition of EDI was triumphantly established by using EDI aptamer as a biorecognition element, which exhibited a wide linear ranking from 5 ng L–1 to 10 μg L–1 (R2 = 0.996) and a low detection limit of 1.667 ng L–1 (S/N = 3). The splendid performance of the ZnPc/n-MoS 2 nanosheet ultrasensitive sensing platform can be applied to detect the concentration of EDI in food, biomedical and environmental analysis. • Visible light-responsive ZnPc/n-MoS 2 was fabricated used ZnPc nanoparticles as sensitizer. • The carrier lifetime and photocurrent intensity of ZnPc/n-MoS 2 is 2 more and 24 times of n-MoS 2 , respectively. • A visible light-driven PEC edifenphos aptasensor was firstly successfully established. • The proposed aptasensor exhibited good selectivity and sensitivity for edifenphos detection. [ABSTRACT FROM AUTHOR]

The residual of atrazine (ATZ) can disrupt the production of testosterone in animals, causing chemical castration in animals. Therefore, the monitoring of ATZ residue is essential for human health and ecological balance. Herein, a novel dual-signal amplification photofuel cells (PFC) aptasensor was proposed. The presence of a hole mediator and hollow structure enhances the efficiency of electron-hole pair separation and visible light absorption in the photoanode. Additionally, the effect of dye sensitization plays a crucial role in improving the conversion efficiency of photon-to-electrons in the photocathode. The as-prepared aptasensor realized sensitive detection of ATZ, with a board linear range from 1.0 × 10−13 ∼ 1.0 × 10−6 mol L−1 and a low detection limit of 3.3 × 10−14 mol L−1. The reliability of the as-prepared PFC aptasensor was verified by gas chromatography-mass spectrometry (GC-MS). Therefore, the manufactured PFC aptasensor is a prospective detection method for fruit and vegetables safety analysis. [Display omitted] • A novel dual-signal amplification photofuel cells aptasensor was established. • Hole mediator was used as a novel strategy to improve the P max of PFC system. • The hollow structure contributes to enhancing the output performance of CdS. • NiPc sensitized Cu 7 S 4 was developed as a novel photocathode material. • A high initial P max with a signal-off response aptasensor for ATZ detection. [ABSTRACT FROM AUTHOR]

Synopsis: Successful preparation of VOPc/CN photoactive materials and construction of PEC aptasensor for DCF detection. • Facile method with easy fabrication enabled the visible/NIR light response PEC sensor for rapid DCF detection. • VOPc/CN nanocomposites was first used as photoactive materials. • VOPc/CN based on VOPc sensitizing CN extend spectral range to visible/ NIR light region. • VOPc/CN photoactive materials demonstrated improved photoelectric conversion efficiency. • This biosensor showed a good sensitivity and a wide linear range. 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. [ABSTRACT FROM AUTHOR]

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 Bi 2 MoO 6 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 Bi 2 MoO 6 remarkably, and the presences of oxygen vacancies can be beneficial to broaden the absorption range. The absorption edge of Bi 2 MoO 6 /BNG was widened from 500 nm to 550 nm compared to Bi 2 MoO 6 , and the charge transfer was accelerated to improve the photoactive of Bi 2 MoO 6 /BNG. Under visible light illumination, the photoelectrochemical (PEC) response of the as-prepared Bi 2 MoO 6 /BNG was 11.6-fold, 6.7-fold, 3.1-fold and 2.4-fold higher than that of pristine Bi 2 MoO 6 , Bi 2 MoO 6 /graphene, Bi 2 MoO 6 /nitrogen doped graphene and Bi 2 MoO 6 /boron doped graphene. Using Bi 2 MoO 6 /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 Bi 2 MoO 6 /BNG nanocomposites exhibit excellent visible light response and PEC performance, indicating its potential applications in PEC biosensor. • Oxygen vacancy engineered Bi 2 MoO 6 /BNG was prepared by one-pot for the first time. • The photocurrent of Bi 2 MoO 6 /BNG was greatly enhanced compared with pristine Bi 2 MoO 6 , Bi 2 MoO 6 /G, Bi 2 MoO 6 /NG and Bi 2 MoO 6 /BG. • A highly efficient PEC lincomycin aptasensor was successfully established. • The proposed aptasensor exhibited excellent superior analytical performance for lincomycin detection. [ABSTRACT FROM AUTHOR]

Dye sensitization is an alternative strategy to improve photoelectric activity of semiconductors and, particularly, to enhance the activity towards visible light domain. Herein, an artificial Z-scheme bipyridine ruthenium (Ru(bpy) 3 2+) sensitizing narrow-gap bismuth oxy-iodide (BiOI) microspheres was constructed by a simple electrostatic interaction strategy for the first time. The electrochemical impedance spectroscopy (EIS) and photoluminescence (PL) analysis showed that this design of such Z-scheme structure was helpful to enhance the interfacial charge transfer and improve the photoelectric conversion efficiency. In addition, due to the sensitization of Ru(bpy) 3 2+, the band gap was narrowed from 1.8 eV of BiOI microspheres to 1.3 eV of BiOI/Ru(bpy) 3 2+ microspheres, leading to improve the utilization of visible light. So that, the photocurrent of the resulted BiOI/Ru(bpy) 3 2+ was 13.0 times that of pure BiOI microspheres. In view of the outstanding photoelectrochemical (PEC) performance of BiOI/Ru(bpy) 3 2+ and the high specificity of the aptamer, the PEC aptasensor for ampicillin (AMP) merits the excellent detection performance including a broad linear ranging from 1 × 10–7 nM to 100 nM as well as a low detection limit of 3.3 × 10–8 nM (S/N = 3). This work not only provides a novel way to construct and design highly efficient photoactive materials for PEC detection, but also broadens the application of Z-scheme in the field of sensing. • BiOI/Ru(bpy) 3 2+ microspheres were successfully prepared, showing a 13-fold photocurrent intensity compared to pure BiOI. • The Z-scheme configuration was helpful to enhance the interfacial charge transfer. • As a sensitizer, Ru(bpy) 3 2+ extended the spectral response of BiOI/Ru(bpy) 3 2+, thus improving the visible light utilization. • The fabricated PEC aptasensor exhibited good selectivity and sensitivity for ampicillin detection. [ABSTRACT FROM AUTHOR]