Recent advances in photoelectrochemical sensors for detection of ions in water

Over the last 50 years,the explosive adoption of modern agricultural practices has led to an enormous increase in the emission of non-biodegradable and highly biotoxic ions into the hydrosphere.Excess intake of such ions,even essential trace elements such as Cu^(2+)and F^(-),can have serious consequences on human health.Therefore,to ensure safe drinking water and regulate wastewater discharge,photoelectrochemical(PEC)online sensors were developed,with advantages such as low energy consumption,inherent miniaturization,simple instrumentation,and fast response.However,there is no publicly available systematic review of the recent advances in PEC ion sensors available in the literature since January 2017.Thus,this review covers the various strategies that have been used to enhance the sensitivity,selectivity,and limit of detection for PEC ion sensors.The photoelectrochemically active materials,conductive substrates,electronic transfer,and performance of various PEC sensors are discussed in detail and divided into sections based on the measurement principle and detected ion species.We conclude this review by highlighting the challenges and potential future avenues of research associated with the development of novel high-performance PEC sensors.

Facile Semiconductor p-n Homojunction Nanowires with Strategic p-Type Doping Engineering Combined with Surface Reconstruction for Biosensing Applications

Photosensors with versatile functionalities have emerged as a cornerstone for breakthroughs in the future optoelectronic systems across a wide range of applications.In particular,emerging photoelectrochemical(PEC)-type devices have recently attracted extensive interest in liquid-based biosensing applications due to their natural electrolyte-assisted operating characteristics.Herein,a PEC-type photosensor was carefully designed and constructed by employing gallium nitride(GaN)p-n homojunction semiconductor nanowires on silicon,with the p-GaN segment strategically doped and then decorated with cobalt-nickel oxide(CoNiO_(x)).Essentially,the p-n homojunction configuration with facile p-doping engineering improves carrier separation efficiency and facilitates carrier transfer to the nanowire surface,while CoNiO_(x)decoration further boosts PEC reaction activity and carrier dynamics at the nanowire/electrolyte interface.Consequently,the constructed photosensor achieves a high responsivity of 247.8 mA W^(-1)while simultaneously exhibiting excellent operating stability.Strikingly,based on the remarkable stability and high responsivity of the device,a glucose sensing system was established with a demonstration of glucose level determination in real human serum.This work offers a feasible and universal approach in the pursuit of high-performance bio-related sensing applications via a rational design of PEC devices in the form of nanostructured architecture with strategic doping engineering.

Colorimetric-assisted photoelectrochemical sensing for dual-model detection of sialic acid via oxidation-power mediator integration

Development of sensitive and accurate methods for sialic acid(SA) determination is of great significance in early cancer diagnosis.Here,a colorimetric-assisted Photoelectrochemical(PEC) sensor was constructed for SA detection based on the two pairs of cis-diol groups in SA molecule.With the specific recognition of SA via the two pairs of cis-diol groups,the prepared gold-modified Bi_(2)S_(3)(AuNPs@Bi_(2)S_(3)) and metal organic framework(Au@PCN-224) were introduced to the electrode and formed a sandwich structure.Based on the properties of inert electroconductivity and nanozyme of the PCN-224,dual-readout of photocurrent and visualization was achieved with the presence of 3',3',5',5'-tetramethylbenzidine(TMB).Moreover,to intensify the visualization signal,Ce^(3+) was employed as the mediator to boost the catalysis capability by transferring energy from PCN-224 surface to the whole system.With the unique SA recognition and the mediation of Ce^(3+),both the photocurrent and the visualization signals sensitively responded with the SA concentration linearly.The present method showed greatly high sensitivity,selectivity and accuracy for SA detection with a limit of detection of 1.44μmol/L and a wide linear range of 5-1000μmol/L.This method provided a new promising platform for SA detection and a potential strategy for design of novel biosensors with dual-model readout.

Bi/BiVO_(4)/NiFe-LDH heterostructures with enhanced photoelectrochemical performance for streptomycin detection

Streptomycin(STR)plays an essential role in bacterial infection treatments.Selectivity and sensitivity of photoelectrochemical(PEC)sensors are the two most important parameters,which can be measured using the photosensitivity of its active material.We prepared a novel PEC sensor to detect STR using Bi/BiVO4/LDH(layered double hydroxides)heterostructures as an active material,which is photoactive in the visible light wavelength range.The simultaneous presence of LDH and Bi/BiVO4 enhanced the material photocurrent response,which was linear to the STR concentrations in the 0.01–500 nmol/L range.The STR detection limit by this sensor was 0.0042 nmol/L.Our novel PEC-based sensing strategy includes using an ultra-sensitive and highly selective sensor for STR detection.Additionally,the two-pot synthesis of Bi/BiVO4/LDH developed in this work is environmentally friendly.

Label-free photoelectrochemical sensor based on 2D/2D ZnIn_(2)S_(4)/g-C_(3)N_(4) heterojunction for the efficient and sensitive detection of bisphenol A

Photoelectrochemical(PEC)sensor is an emerging technology in analysis as the advantage of fast re-sponse,high sensitivity and uncomplicated operation.In this study,an effective label-free PEC sensor for bisphenol A(BPA)detecting is constructed,in which Zn In_(2)S_(4)/g-C_(3)N_(4)heterojunction is prepared via a sim-ple hydrothermal method.The characterization outcomes display that the formation of p-n heterojunction helps for promoting the separation efficiency of photo-generated carrier.Under visible light irradiation,the Zn In_(2)S_(4)/g-C_(3)N_(4)modified electrode exhibits broader liner range from 0.05 mmol/L to 30 mmol/L and lower detection limit of 0.016μmol/L(S/N=3)with remarkable stability and reproducibility of detection BPA under visible light irradiation.Furthermore,the constructed PEC sensor displays favorable potential for detection of BPA in practical applications.

A Label-free Photoelectrochemical Sensor Based on Bi_(2)S_(3)@Nitrogen Doped Graphene Quantum Dots for Ascorbic Acid Determination

We report a photoelectrochemical(PEC)sensor for selective detection of ascorbic(AA)by introducing Z-scheme Bi_(2)S_(3)@nitrogen doped graphene quantum dots(Bi_(2)S_(3)@NGQDs)heterojunctions as efficient photoactive species.The Bi_(2)S_(3)@NGQDs were successfully prepared by a simple hydrothermal process,and the microstructures and components were investigated by various characterized techniques.The photocurrent of the Bi_(2)S_(3)@NGQDs-based sensor increased significantly in the presence of AA and showed excellent selectivity and stability for AA detection in the presence of some other antioxidants and small molecules.A wide linear range of 0.1–5µmol/L and 5–1380µmol/L was achieved for the AA detection with a detection limit of 36 nmol/L(S/N=3).Moreover,the proposed PEC sensor achieved the determination of AA in real red peppers and commercially available vitamin C tablets samples.