Biological redox cycling amplification in a self-powered photoelectrochemical sensor based on TiO2/CdIn2S4/ g-C3N4-WO3 photoanode for sensitive detection of Hg2

Constructing BiOI@Nv/g-C3N4 with S-scheme heterojunction for enhanced photoelectrochemical performances towards highly sensitive and selective detection of trace chlorpyrifos

Chlorpyrifos, one of the organophosphorus pesticide commonly used in the environment, may bring about an irreversible harm such as lung cancer to human body. Photoelectrochemical (PEC) detection techniques based on g-C3N4 for sensing chlorpyrifos have attracted increasing attentions, but impeded by several inherent constraints such as a limit of active sites and carriers transfer. To conquer these challenges, a photoelectrochemical sensor of BiOI@Nv/g-C3N4 with a step scheme heterojunction was thereby proposed for the sensitive and selective detection of trace chlorpyrifos. Herein, the created N vacancies facilitated the migration of photo-electrons from BiOI to recombine with the holes of Nv/g-C3N4 under light irradiation. A powerful oriented built-in electric field was established directing from Nv/g-C3N4 to BiOI. The photocurrent intensity of the as-prepared sensor exhibited over 7.6 times higher than that of pure g-C3N4, showing a well PEC performance. High selectivity of the developed sensor was attributed to the specific interaction between Bi sites of the developed composites and the S, N atoms in chlorpyrifos. Such sensitive and steady PEC sensor exhibited a linear detection range from 0.01 to 20 ppb with a detection limit of 0.004 ppb. Further, the sensor displayed reliable performance when applied to real river water and soil samples, achieving nice recovery rates. Unlike traditional PEC sensor, this one was prepared into S-scheme heterojunction by creating a N defect-induced driving force based on the altered built-in electric field. The work not only provides experimental evidences but also advances the fundamental theories so as to offer a robust g-C3N4-based PEC platform for environmental analysis.

Progress in Signal Amplification and Microstructure Manufacturing for Photoelectrochemical Sensing

Photoelectrochemical (PEC) sensing based on chemical or biological recognition has received a tremendous amount of attention in recent years, providing analytical chemists a plethora of opportunities. However, emerging techniques and unknown processes in this field remain unexplored. We summarize the recently reported PEC sensing methods. First, we briefly describe the basic principles and technical characteristics of PEC sensing. Next, we highlight the application of various materials, nucleic acids, and other strategies for amplifying PEC signals. Finally, we discuss the current state of knowledge regarding the realization of miniaturized equipment during PEC sensor manufacturing. Summarizing the technological advances and research breakthroughs in PEC sensing over time can help increase the quality of follow-up research.

Noble metal/metal-organic framework nanoparticle-based electrochemical sensors for evaluating fish quality: a comprehensive review

Fish quality is a big-picture issue because of the possible presence of many chemical and biological pollutants, that may affect fish leading to environmental and health hazards. In this regard, researchers focus on developing efficient strategies for evaluating fish quality in terms of safety and freshness. Fish safety is determined based on assessing various pollutants, such as heavy metals, pesticides, dyes, and drugs, in fish tissue. Additionally, fish freshness evaluation is based on assessing some indicators including xanthine, hypoxanthine, uric acid, and histamine. Many chromatographic methods can assess all of these chemical indicators to evaluate the fish quality. However, these methods are expensive and often require sophisticated steps. Thus, electrochemical methods based on noble metal nanoparticles (NMNPs), metal-organic frameworks (MOFs) NPs, and their composites as electrode modifiers were investigated as potential replacements for the chromatographic ones. These materials showed high catalytic activity and electrical conductivity compared to the other electrode modifiers. In this review, we spotlight the role of NMNPs and MOF NPs in evaluating the quality of fish samples as a food source. Overall, NMNPs and MOF NPs are considered promising electrode materials for the electrochemical monitoring of fish quality.

Research progress of photoelectrochemical sensors in food detection

Food is the basic of the people, security is the basic of the food. As the quality of life improves, food safety has emerged as a global concern, making the development of simple, rapid, and efficient food safety detection methods critically important. Photoelectrochemical (PEC) sensors are a novel class of sensors developed in recent years that integrate photoelectric technology with biosensing. Owing to their high sensitivity, simple design, low cost, and ease of miniaturization, PEC sensors have found widespread applications in food detection, bioanalysis, clinical diagnostics, and environmental protection. This paper reviews the development of PEC sensors, the basic principles of PEC sensor detection, and the electron transport pathways of semiconductor materials in PEC sensors. It focuses on how photoelectroactive materials and related signal amplification strategies can improve the detection performance of the sensors, as well as the latest research advances of PEC sensors in the detection of food toxins. Finally, the challenges and future trends of PEC sensors in food safety detection are discussed.

Photoelectrochemical sensor for nitrite determination based on the etching of BiOCl/Zn0.5Cd0.5S

A rapid photoelectrochemical (PEC) sensor was constructed for nitrite detection in food based on the one-step chemical etching strategy of BiOCl/Zn0.5Cd0.5S (BOC/ZCS) nanocomposites by nitrite. BOC/ZCS heterojunction was prepared by a simple coprecipitation method, and it was found that BOC/ZCS showed significant photoelectrochemical (PEC) activity. The results of this study confirmed that the decrease in the photocurrent of the sensor was linked to the etching of ZCS by nitrite under acidic conditions. Under optimized conditions, the BOC/ZCS-based PEC sensor showed good analytical properties for detecting nitrite, with linear ranges of 1-100 μM and 100-600 μM. The detection limit of the sensor was 0.41 μM (S/N = 3). Excellent repeatability, reproducibility, low background noise, and immunity to interference were demonstrated using the proposed system, and satisfactory results were achieved for the nitrite assay using real samples. These results demonstrate a new method for nitrite detection developed using the proposed PEC sensor.

Sensitive detection of Hg(II) on MoS2/NiS2 based on interfacial engineering to accelerate the Ni2+/Ni3+ cycle: Identification the role of atomic-level heterojunction-induced electron transfer in electroanalysis

The valence change of transition metal ions in nanomaterials can highly enhance the electrochemical detection performance toward heavy metal ions (HMIs), and how to further promote the valence change calls enormous concerns in electroanalysis. In this work, an interfacial engineering that combing the MoS2 and NiS2 together to form the MoS2/NiS2 complex is proposed. The density functional theory (DFT) results reveals that the novel atomic-level heterojunction between MoS2 and NiS2 will build an internal electric field (IEF), which leads to an enhanced conductivity and valence change behavior of Ni atoms in MoS2/NiS2 complex, resulting in a superior detection performance. In detail, the formation of atomic-level heterojunctions in the MoS2/NiS2 complex accelerates electron transfer due to the valence changes associated with Ni2+/Ni3+ cycling. The active Mo4+ species on MoS2 act as electron donors, facilitating the reduction of Ni3+ to Ni2+ on NiS2, thereby promoting Ni2+/Ni3+ cycling. As anticipated, the MoS2/NiS2 complex exhibits exceptional detection performance for Hg(II), with a sensitivity of 459.13 μA μM-1 cm-2, surpassing even that of other composite materials. In general, these findings are expected to significantly advance the application of electron transfer acceleration in electroanalysis based on the construction of heterojunction.

Ternary BiOI/Bi2S3/Au Nanosheet Arrays as a Photoelectrochemical Signal Converter for the Detection of Cardiac Troponin I

Nanosheet arrays with stable signal output have become promising photoactive materials for photoelectrochemical (PEC) immunosensors. However, an essential concern is the facile recombination of carriers in one-component nanoarrays, which cannot be readily prevented, ultimately resulting in weak photocurrent signals. In this study, an immunosensor using gold nanoparticle-anchored BiOI/Bi2S3 nanosheet arrays (BiOI/Bi2S3/Au) as a signal converter was fabricated for sensitive detection of cardiac troponin I (cTnI). The ternary nanosheet arrays were prepared by a simple method in which Bi2S3 was well-coated on the BiOI surface by in situ growth, whereas the addition of Au further improved the photoelectric conversion efficiency and could link more antibodies. The three-dimensional (3D) ordered sheet-like network array structure and BiOI/Bi2S3/Au ternary nanosheet arrays showed stable and high photoelectric signal output and no significant difference in signals across different batches under visible light excitation. The fabricated immunosensor has a sensitive response to the target detection marker cTnI in a wide linear range of 500 fg/mL to 50 ng/mL, and the detection limit was 32 fg/mL, demonstrating good stability and selectivity. This work not only shows the great application potential of ternary heterojunction arrays in the field of PEC immunosensors but also provides a useful exploration for improving the stability of immunosensors.