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2D nickel phthalocyanine based MOFs (NiPc-MOFs) with excellent conductivity were synthesized through a solvothermal approach. Benefiting from excellent conductivity and a large surface area, 2D NiPc-MOF nanosheets present excellent electrocatalytic activity for nitrite sensing, with an ultra-wide linear concentration from 0.01 mM to 11 500 mM and a low detection limit of 2.3 μM, better than most reported electrochemical nitrite sensors. Significantly, this work reports the synthesis of 2D conductive NiPc-MOFs and develops them as electrochemical biosensors for non-enzymatic nitrite determination for the first time. 

A novel electrochemical dopamine sensor was fabricated based on a composite film solely consisting of kappa-carrageenan and hierarchical porous carbon drop-casted onto a glassy carbon electrode in a conventional three electrode system. Graphene oxide was synthesized in a one-step thermal conversion from base-catalyzed alkali lignin. Five ratios by mass of a novel hierarchical porous activated carbon and kappa-carrageenan were studied for dopamine quantification without synthetic binders such as polytetrafluoroethylene. Various tests were performed to explicate structure and electrochemical properties of the films. Utilizing differential pulse voltammetry for detection, the optimized 10:1 ratio system elicited a linear range of 1–250μmol l⁻¹and a limit of detection of 0.14μmol l⁻¹(S/N = 3). Results suggested an effective new combination of materials for non-enzymatic dopamine sensing.

 

Electrochemical sensors for mercury ion detection would ideally demonstrate wide linear detection ranges (LDRs), ultratrace sensitivity, and high selectivity. This work presents an electrochemical sensor based on metallic 1T phase tungsten disulfide (WS₂) microflowers for the detection of trace levels of Hg²⁺ions with wide LDRs, ultratrace sensitivity, and high selectivity. Under optimized conditions, the sensor shows excellent sensitivities for Hg²⁺with LDRs of 1 nm–1 µmand 0.1–1 mm. In addition to this, the limit of detection of the sensor toward Hg²⁺is 0.0798 nmor 79.8 pm, which is well below the guideline value recommended by the World Health Organization. The sensor exhibits excellent selectivity for Hg²⁺against other heavy metal ions including Cu²⁺, Fe³⁺, Ni²⁺, Pb²⁺, Cr³⁺, K⁺, Na⁺, Ag⁺, Sn²⁺, and Cd²⁺. The thus‐obtained excellent sensitivity and selectivity with wide LDRs can be attributed to the high conductivity, large surface area microflower structured 1T‐WS₂, and the complexation of Hg²⁺ions with S²⁻. In addition to good repeatability, reproducibility, and stability, this sensor shows the practical feasibility of Hg²⁺detection in tap water suggesting a promising device for real applications.