2-Chloro-4-nitrophenol (2C4NP) is a traditional organic pollutant whose toxicity constitutes a significant threat to both human health and environmental safety. Therefore, developing a method for the accurate detection of 2C4NP in natural environments is imperative. Consequently, we develop a photoelectrochemical sensing platform based on MWCNTs@In2S3/In2O3/GCE in this work. During the construction process, it is discovered that the introduction of MWCNTs accelerated the electron transport rate, which improved the separation efficiency of photogenerated electron-hole pairs in In2S3. Meanwhile, the MWCNTs@In2S3/In2O3 composite materials formed by MWCNTs@In2S3 and In2O3 not only exhibit an S-scheme heterojunction but also preserve the intrinsic advantages of MOFs-derived materials. This synergistic structure endows the composite materials with excellent optoelectronic performance and adsorption capability. Thus, the constructed photoelectrochemical sensing platform demonstrates promising potential for detecting 2C4NP, with a linear detection range from 3 nM to 5 μM. However, compared to some existing platforms, its detection range remains relatively narrow, which may represent an area for future improvement.

Flutamide (FLU), a nonsteroidal antiandrogen drug for prostate cancer therapy, requires sensitive monitoring due to its narrow therapeutic window. Herein, we constructed a novel photoelectrochemical sensor based on an S-scheme Bi2S3/FeIn2S4 heterojunction for ultrasensitive FLU detection. This charge transfer mechanism was confirmed through density functional theory calculations and electron paramagnetic resonance tests. FLU can act as a hole scavenger by transforming its nitro group into a nitroso derivative via a 2e-/2H+ transfer process, thereby amplifying the photocurrent signal. The sensor outperformed traditional techniques, exhibiting a wide dual-range linear detection capability (0.02 - 20 μM and 20 - 110 μM) with an ultralow detection limit of 10 nM. The designed sensor exhibits good repeatability and long-term storage stability (>92.8%). Moreover, this sensor was successfully applied in human serum and urine, with recovery rates ranging from 96.9% to 100.2%.

Ornidazole (ONZ) is a widely used nitroimidazole-class antibiotic whose environmental persistence due to misuse intensifies antimicrobial resistance and accelerates pathogen evolution, posing serious risks to human health and ecological safety. To address this issue, we developed a novel photoelectrochemical (PEC) sensor for ultrasensitive ONZ detection based on a p-n heterojunction between pseudobrookite-type oxide MgTi2O5 and the metal-organic framework (MOF) Cu-BTC. Density functional theory (DFT) calculations corroborate the favorable band structure of the heterojunction. The built-in electric field and S-scheme charge transfer at the interface enable efficient separation of photogenerated carriers, yielding an ultralow detection limit of 0.65 pM, a wide linear range from 1 pM - 10 nM (R2 = 0.9992), and excellent anti-interference, selectivity, stability and reproducibility. The sensor achieved 98.43% - 103.62% recovery in real samples including commercial capsules, tablets, and environmental water, demonstrating high practical reliability. This work presents a cost-effective, portable, and high-performance platform for ONZ monitoring and offers new insights into advanced PEC sensor design for antibiotic pollution detection.

Shikonin (SHI) possesses antibacterial, anti-inflammatory, and wound-healing properties but requires strict content monitoring in pharmaceuticals, cosmetics, and food products due to potential toxicity and concentration variations. This study proposes the construction of bimetallic oxide heterojunctions to enhance electrocatalytic performance. Using a controlled MOF-on-MOF heterogeneous internal expansion growth method (IEGM), a nitrogen-doped carbon-based bimetallic oxide nanocomposite, ZrO2@Pr2O3@NC, was synthesized via programmed calcination. This material, featuring a high surface area and abundant active sites, was created a sensitive electrochemical sensing interface for SHI detection. Combining experimental characterization with theoretical simulation analysis reveals that the Pr-O-Zr bonds formed at the heterointerface induce an intrinsic electric field, which affords efficient pathways for rapid charge transfer and reactant mass transport and thus markedly enhances the electrocatalytic oxidation performance of the material. Under the optimized experimental conditions, the sensor exhibited a linear response toward the target over a concentration range of 5-5000 nM, with a corresponding limit of detection (LOD) as low as 1.25 nM, and it displayed excellent accuracy, stability, and anti-interference capability in real sample analysis. This work offers a novel sensing platform for natural product analysis and insights into designing high-performance heterojunction electrocatalytic materials.

As a broad-spectrum antibiotic, metronidazole (MTZ) is extensively used in clinical and aquaculture fields. However, its continuous overuse leads to severe environmental accumulation, posing significant ecotoxicological risks and threatening human health. Herein, we developed an ultra-sensitive, eco-friendly electrochemical sensor for MTZ. The novelty of this work lies in utilizing natural biomass guanine as a dual carbon/nitrogen precursor and non-toxic phosphoric acid to in situ anchor bimetallic nickel-cobalt phosphide (NiCoP) onto nitrogen-doped porous carbon (NiCoP/GC) via a facile one-step process. Mechanistically, the synergistic effect among the highly conductive nitrogen-doped carbon skeleton, NiCoP bimetallic centers, and highly electronegative phosphorus significantly accelerates the proton-dependent electroreduction kinetics of MTZ. Providing specific quantitative advantages, the sensor achieves a broad linear range (0.05–350 μM) and an ultra-low detection limit of 0.029 μM. Crucially, it exhibits excellent anti-interference and reproducibility in complex real matrices, including honey, milk, and environmental water. In summary, the successful integration of biomass-derived carbon and bimetallic phosphide yields an ultra-sensitive sensor, providing a robust green platform for monitoring antibiotic residues in food and environmental ecosystems.

The design and construction of effective photoelectrochemical (PEC) sensing materials for high-performance detection of the natural product Shikonin (SHI) represent the highly challenging and unreported task. In this study, the first SHI PEC sensing platform based on an S-scheme heterojunction was constructed by sensitizing defect-rich Sb1.75Bi0.25S3 solid solution with pyrochlore-structured Bi2Sn2O7. The defect-induced interfacial charge transfer mechanism effectively passivates the deep-level defects inherent in the chalcogenide, facilitating efficient separation of photogenerated charge carriers. Under visible light irradiation, SHI molecules are oxidized by photogenerated holes, which not only promotes charge separation but also results in a significant enhancement of the photocurrent response. Density functional theory (DFT) calculations elucidate the charge transfer dynamics within the Bi2Sn2O7/Sb1.75Bi0.25S3 heterojunction, confirming electron migration from Sb1.75Bi0.25S3 to Bi2Sn2O7 and the formation of an internal electric field at the heterointerface. The optimized PEC sensor exhibits a broad linear range from 0.02 to 50 mu M with a low limit of detection of 7.38 nM for SHI, along with excellent specificity, stability, and reproducibility. Satisfactory recovery rates in real sample analyses further demonstrate its reliability and practical applicability for the sensitive detection of SHI in complex matrices.

Amaranth (AM) is a widely used synthetic azo food colorant that poses severe toxicological risks upon excessive consumption, creating an urgent need for its ultra-sensitive detection. We report a high-performance electrochemical sensor based on the electrostatic co-aggregation of V2O3@NC and NHCS for the high-fidelity quantification of AM. A unique “capture-and-catalysis” synergistic mechanism governs this composite interface. Specifically, the highly porous NHCS framework provides exceptional capacity to capture and pre-concentrate target molecules while acting as a highly conductive “electronic bridge.” Subsequently, the abundant mixed-valence (V3+/V5+) sites of the V2O3@NC serve as a robust electrocatalytic engine to drive the catalysis, significantly amplifying the AM oxidation signal. Combining electrochemical kinetic analysis with DFT calculations (including HOMO and MEP), we reveal that this electrocatalytic evolution proceeds via a directional 1 H+/2e− transfer mechanism. Under optimal conditions, the V2O3@NC/NHCS sensor exhibits a broad linear range (0.01–12 µM) and an extremely low LOD of 0.80 nM. Practical analysis of commercial beverages yielded recoveries of 95.0

Chlorogenic acid (CA) is a phenolic acid compound with broad biological activity. In this study, a high-performance photoelectrochemical sensor based on in situ grown ZnIn2S4@ZnWO4 heterojunctions was developed for the sensitive detection of CA. ZnWO4 nanocrystals were successfully grown on the surface of flower-like ZnIn2S4 through a one-step hydrothermal method, resulting in a tightly coupled heterojunction structure that effectively promoted photo-induced charge separation and enhanced photocurrent response. Experimental results demonstrated that the sensor exhibited excellent analytical performance for CA, with a good linear relationship within a concentration range of 20-800 nM, a detection limit as low as 5 nM (S/N = 3), and high selectivity, stability, and reproducibility. Density functional theory (DFT) calculations revealed the charge transfer mechanism at the heterojunction interface and the interaction between CA and the material surface. Practical sample analysis showed that the sensor was successfully applied to accurately determine CA content in coffee, eucommia ulmoides oliver and lonicera japonica thunb, with recovery rates ranging from 97.08 to 103.56%. This study provides a new method for CA detection and offers fresh insights into the design of efficient photoelectrochemical sensors.

To overcome the poor conductivity of pure MOFs and the structural collapse of MOF-derived carbons, this study constructed an electrochemical sensing interface by integrating high-surface-area UiO-66-NH2 with catalytically active bimetallic CoFe alloy-embedded N-doped carbon nanosheets (CoFe@NC). The composite exhibits uniform morphology, clear crystal structure, and a large specific surface area (227.58 m2·g-1), which contribute to enhanced enrichment and detection performance toward CA. This sensor demonstrates a wide linear range (0.001-7 μM) and an ultralow detection limit (0.29 nM), along with excellent anti-interference ability, reproducibility, and stability. By combining density functional theory (DFT) calculations with electrochemical experiments and in-situ Raman characterization, the roles of various components in composite materials during the CA oxidation process, the regulatory mechanism of bimetallic alloys on the electronic structure of the material, the reaction mechanism of CA at the sensing interface, and the synergistic enhancement effect of the bimetallic system were elucidated. When applied to red wine, green tea, blueberries, and apple peel, recoveries of this sensor ranged from 97.2 to 103.8%. The quantitative results were in excellent agreement with those obtained by ultraviolet-visible (UV-vis) spectrophotometry and high performance liquid chromatography (HPLC), confirming the high accuracy and reliability of this sensor. This work not only provides a high-performance sensing platform for trace CA detection in food but also offers a novel strategy for the design and application of electrochemical sensors based on hierarchically structured MOF composites through the deep integration of experimental and theoretical approaches.

Chlorogenic acid (CGA), a core antioxidant in functional foods, requires accurate and rapid monitoring to ensure food quality, safety and production standardization, which is the practical and theoretical basis for developing its dedicated sensor. Unlike traditional HPLC (complex preprocessing, high cost, time-consuming), this study synthesized a NiFe2O4/A-CN composite by pyrolyzing a two-dimensional zeolite imidazole framework to obtain accordion-like N-doped carbon (A-CN), followed by ultrasonic loading of hydrothermally prepared NiFe2O4 nanoparticles. The composite combines A-CN's conductive framework with NiFe2O4's electroactive sites, creating a synergistic interface that efficiently adsorbs and detects CGA. The resulting electrochemical sensor shows a wide linear range (5 × 10-10-2 × 10-6 M), ultra-low detection limit (1.0 × 10-11 M), excellent recovery (98.9-102.2%) in actual food samples (yellow peaches, lemons, Tangerines), validated by UV-Vis, offering a faster, more cost-effective alternative for rapid and precise CGA detection in foods.

Flutamide (Flu) is an antiandrogen drug associated with various side effects at high concentrations. A core-shell composite, MoG@ZIF-67@MIL-101, was synthesized through an in situ growth method using Mo-glycerate (MoG) solid spheres as the core and a MOF-on-MOF structure (ZIF-67@MIL-101) as the shell. After controlled carbonization, a CoFe bimetallic alloy nanoparticles @ metal carbide material (CoFe@Fe3Mo3C) with a unique core-shell structure was successfully obtained, in which strong electronic coupling was formed, exhibiting excellent electrocatalytic synergy. The successful construction of the MOF-on-MOF structure and the composite material was confirmed through various physical characterizations. Subsequently, the material was integrated with graphene oxide @ carbon nanobubbles (GO@CNB) to develop a CoFe@Fe3Mo3C/GO@CNB/GCE electrochemical sensor for Flu detection. Owing to the composite's outstanding conductivity and electrocatalytic activity, the sensor exhibited a wide linear range of 5.0 nm-10.0 µm and an ultralow detection limit of 3.4 nm. Density functional theory calculations showed that the composite possesses the strongest adsorption energy for Flu (-1.50 eV) and elucidated the electrochemical reaction mechanism. The sensor achieved recoveries of 96%-105% in water sample analysis, demonstrating its practical applicability. This study highlights the significant potential of integrating core-shell MOF-on-MOF-derived alloy carbide materials with 2D conductive carbon nanomaterials for environmental analysis.

Tert-butylhydroquinone (TBHQ), a widely used antioxidant for extending food shelf life, requires strict content control to ensure food safety. Here, we constructed a core-shell CdMoO4@ZnS S-scheme heterojunction via in situ growth for highly sensitive detection of TBHQ. Compared with our previously reported heterojunction sensors, this system achieves synergistic enhancement through polyvinylpyrrolidone-mediated morphology regulation and optimal shell-thickness engineering, effectively mitigating limitations in charge separation and stability. The developed photoelectrochemical sensor exhibits a wide dual-range detection capability (0.015-20 mu M and 20-190 mu M) with an ultralow detection limit of 1.8 nM. The exceptional sensing performance was elucidated by density functional theory calculations and redox potential analysis. Furthermore, the sensor achieves excellent recovery rates (97.05%- 104.23%) in real-sample analyses and retains more than 91.33% of its initial response after 8 weeks of storage, highlighting its strong potential for practical food-safety monitoring applications.

Rational regulation of the interface and realization of synergistic electrocatalytic activity in functionalized structure represent a key strategy for developing high-selectivity electrochemical sensors toward emerging environmental pollutants. In this work, a hierarchical Ti3C2/Co@CeO2-NCNT composite electrode was rationally designed and fabricated via defect and interface engineering, and employed innovatively as a high-performance sensing platform for trace-level detection of bithionol (BT) in aquatic environments. In this architecture, the 2D conductive Ti3C2 framework effectively disperses and stabilizes Co@CeO2-NCNT components, providing abundant pathways for efficient electron transfer. The as-obtained sensor delivers outstanding analytical performance, including a low limit of detection 2.82 nM, a wide linear range of 5 nM to 9 μM, and excellent stability and practicality in real water samples with satisfactory recoveries of 97.3% - 104.4%. Density functional theory (DFT) calculations confirm that p-d-f orbital hybridization greatly enhances BT adsorption, interfacial charge-transfer kinetics, and overall catalytic efficiency. This work not only provides a novel and sensitive electrochemical platform for BT detection, but also offers valuable guidance for the targeted design of advanced electrocatalytic materials for specific environmental pollutants by clarifying the synergistic mechanism of interface engineering and defect modulation.

On-site monitoring of the emerging organic pollutant chlorpromazine (CPZ) is severely limited by the absence of low-cost, portable, and high-performance sensors. Herein, a disposable screen-printed sensor (Ce-ZnO-CNF@CC/SPE) was fabricated by in-situ growing Ce-doped ZIF-8 on cotton-derived carbon, followed by a one-step pyrolysis strategy. Density functional theory (DFT) calculations confirmed that trace Ce doping induces robust p-d-f orbital hybridization with the host lattice without structural disruption. The introduction of Ce 4f impurity levels narrows the band gap and significantly elevates the density of states near the Fermi energy. This robust electronic modulation accelerates charge-transfer kinetics and optimizes the CPZ adsorption affinity. Under optimized conditions, the fabricated sensor exhibited a remarkably broad linear range and an ultra-low limit of detection, along with excellent anti-interference, reproducibility, and stability. Furthermore, highly accurate and reliable recoveries were achieved in complex real-world matrices, including human serum and environmental water samples. This work provides a reliable portable platform for on-site CPZ monitoring and establishes an electronic structure-activity paradigm for designing highly dispersed, biomass-derived carbon-based sensors.

Chlorogenic acid (CGA) is a key antioxidant in functional foods. Herein, we developed a composite via a novel method combining a confinement strategy with stepwise phosphidation to prepare a composite where PdZn alloy is confined within ZIF-8-derived hollow carbon nanocages (PdZn/NP@C), for constructing a CGA sensing platform. By confining the Pd metal precursor within ZIF-8, the aggregation of metal particles was effectively prevented during pyrolysis, and the alloying process between Pd and Zn was facilitated, enhancing the material's conductivity and catalytic activity. Density functional theory (DFT) calculations showed that the PdZn bimetallic structure exhibits superior charge transfer capability to monometallic, improving the adsorption and oxidation reaction efficiency of CGA molecules. The sensor exhibited a linear response from 0.005 to 7.0 mu M with a 1.2 nM detection limit. The results were validated against high-performance liquid chromatography (HPLC) measurements in real samples. The platform thus demonstrated good accuracy and practicality, and can be integrated into portable devices.

Accurate determination of myricetin (Myr) is essential due to its significant bioactivity and potential adverse effects at excessive intake. Herein, a MnFe2O4 composite based electrochemical sensing platform was constructed to achieve highly sensitive Myr detection through synergistic electrocatalysis and enhanced interfacial electron transfer. The composite was synthesized via an in-situ growth followed by high-temperature pyrolysis, in which MnFe2O4 nanoparticles were uniformly anchored onto polypyrrole nanotubes and subsequently converted into a conductive carbon framework. This transformation effectively improves electrical conductivity, suppresses aggregation, and enhances structural stability. The resulting hierarchical structure provides abundant active sites and facilitates rapid charge transport, leading to significantly enhanced electrochemical response toward Myr oxidation. Under optimized conditions, the sensor exhibited a wide linear range of 0.005–5 μmol L−1 and a low limit of detection (LOD) of 2.30 nmol L−1. Additionally, the sensor demonstrated excellent reproducibility, stability, and anti-interference capability. Its practical applicability was confirmed by successful determination of Myr in real samples, with results consistent with those obtained by ultraviolet-visible (UV–Vis) spectroscopy. These findings provide an effective strategy for developing high-performance spinel ferrite‑carbon-based electrochemical sensors for bioactive compound analysis.

ABSTRACT Flutamide (Flu) is an antiandrogen drug associated with various side effects at high concentrations. A core–shell composite, MoG@ZIF‐67@MIL‐101, was synthesized through an in situ growth method using Mo‐glycerate (MoG) solid spheres as the core and a MOF‐on‐MOF structure (ZIF‐67@MIL‐101) as the shell. After controlled carbonization, a CoFe bimetallic alloy nanoparticles @ metal carbide material (CoFe@Fe 3 Mo 3 C) with a unique core–shell structure was successfully obtained, in which strong electronic coupling was formed, exhibiting excellent electrocatalytic synergy. The successful construction of the MOF‐on‐MOF structure and the composite material was confirmed through various physical characterizations. Subsequently, the material was integrated with graphene oxide @ carbon nanobubbles (GO@CNB) to develop a CoFe@Fe 3 Mo 3 C/GO@CNB/GCE electrochemical sensor for Flu detection. Owing to the composite's outstanding conductivity and electrocatalytic activity, the sensor exhibited a wide linear range of 5.0 n m –10.0 µ m and an ultralow detection limit of 3.4 n m . Density functional theory calculations showed that the composite possesses the strongest adsorption energy for Flu (−1.50 eV) and elucidated the electrochemical reaction mechanism. The sensor achieved recoveries of 96%–105% in water sample analysis, demonstrating its practical applicability. This study highlights the significant potential of integrating core–shell MOF‐on‐MOF‐derived alloy carbide materials with 2D conductive carbon nanomaterials for environmental analysis.

The development of efficient photoelectrochemical (PEC) sensing materials for the food additive carmine (CRM) remains a significant challenge, with no PEC sensor reported for CRM to date. Herein, we reported the first PEC sensor based on an Sb2WO6/CuO p-n heterojunction for CRM detection. The heterojunction interface facilitated efficient charge separation through an internal electric field, as elucidated by density functional theory calculations. The detection mechanism relied on the specific binding between the carboxyl and hydroxyl groups in CRM molecules and the metal sites on the CuO surface. This interaction blocked the active sites, inhibited hole transfer, and led to a significant decrease in photocurrent. The sensor exhibited a wide linear range (0.4 - 500 μM), a low limit of detection (0.19 μM), and excellent stability (>96.74%). Furthermore, its successful application in beverage samples yielded recovery rates of 97.30 - 101.50%. This work provides a novel PEC platform for sensitive food additive monitoring.

The development of efficient and sensitive electrochemical sensors for caffeic acid (CA) detection is critical for food safety and human health monitoring. However, conventional metal-organic framework (MOF) derivatives often suffer from particle agglomeration and limited electrical conductivity. Herein, we propose a novel in-situ growth strategy to construct a core-shell Co-MoO2@C composite, which is further integrated with multi-walled carbon nanotubes (CNTs) to achieve a "dispersive-supportive-catalytic" trifunctional sensing platform. Specifically, ZIF-67 was grown in situ on MoO3 nanorods to form a core-shell MoO3@ZIF-67 precursor. Upon pyrolysis, this unique structure effectively prevented the agglomeration of Co nanoparticles and generated abundant Co-Mo-O active sites and heterojunction interfaces. The subsequent incorporation of CNTs not only constructed a highly conductive network but also significantly increased the electroactive surface area (3.65 mm2) and adsorption capacity (1.744 nM & sdot;cm-2) via synergistic effects. The limit of detection (LOD) of the Co-MoO2@C/ CNTs/GCE sensor for CA was 8.4 x 10-10 M under the most suitable conditions. This work provides a new paradigm for designing MOF-oxide-carbon ternary composites for advanced electrochemical sensing applications.

Metal-organic frameworks (MOFs) are typically employed in electrochemical sensing via pyrolysis of pristine MOFs or physical mixing with other materials. However, inadequate structural control often results in poor reproducibility and unstable performance. Furthermore, conventional methods for caffeic acid (CA) detection struggle to meet portability requirements. To address these issues, we developed a surfactant-assisted interfacial growth strategy to construct an NH2-MIL-125(Ti)@MIL-101(Cr) MOF-on-MOF heterostructure, which was subsequently converted through controlled pyrolysis into a TiO2-N-doped carbon nanocake@Cr2O3‑carbon nanonets (TiO2-NCC@Cr2O3-CNN) composite for a portable electrochemical sensor. This material synergistically integrates the robust electrocatalytic activity of multi-metal-oxide heterointerfaces with the outstanding conductivity of the N-doped carbon matrix. Consequently, it enables the ultrasensitive CA detection with a limit of detection of 1.04 nM. Density functional theory calculations reveal that the heterointerface significantly enhances CA adsorption and accelerates charge transfer, thereby elucidating the electronic origin of the improved sensing performance. Finally, the sensor demonstrates excellent analytical performance in actual samples, including schizonepeta, red wine, and perilla leaves. This work not only achieves controllable synthesis of functional heterostructured materials via a MOF-on-MOF strategy but also provides a novel, portable, high-performance electrochemical platform for trace-level detection in food safety applications.