MOF-Derived Zn-Doped CoSe₂ as an Efficient and Stable Free-Standing Catalyst for Oxygen Evolution Reaction

Developing highly active electrocatalysts with low cost and high efficiency for oxygen evolution reactions (OER) is important for the practical implementations of hydrogen energy. Here, we report a Zn-doped CoSe₂ nanosheets grown on free-standing carbon fabric collector (CFC), which was synthesized by using a metal–organic framework (MOF) as precursor and followed by a selenylation process. Importantly, the Zn-doped CoSe₂/CFC electrode exhibited an obviously enhanced catalytic activity for OER in 1 M KOH aqueous solution compared with CoSe₂/CFC, showing a small overpotential of 356 mV for a current density of 10 mA cm^–2, a small Tafel slope of 88 mV dec^–1, and an excellent stability. The robust and free-standing electrode shows great potential as an economic catalyst for OER applications

Simultaneous Detection of Dihydroxybenzene Isomers with ZnO Nanorod/Carbon Cloth Electrodes

Herein, ZnO nanorods with an average diameter of 50 nm were uniformly anchored on the surface of carbon cloth directly by a simple hydrothermal method. The nanorods growing in situ along the specific direction of (002) have single-crystalline features and a columnar structure. On the basis of the ZnO nanorod/carbon cloth composite, free-standing electrodes were fabricated for the simultaneous determination of dihydroxybenzene isomers. The ZnO nanorod/carbon cloth electrodes exhibited excellent electrochemical stability, high sensitivity, and high selectivity. The linear ranges of concentration for hydroquinone, catechol, and resorcinol were 2–30, 2–45, and 2–385 μM, respectively, and the corresponding limits of detection (S/N = 3) were 0.57, 0.81, and 7.2 μM. The outstanding sensing properties of ZnO/carbon cloth electrodes have a great promise for the development of free-standing biosensors and other electrochemical devices

Template-Assisted Synthesis of Nickel Sulfide Nanowires: Tuning the Compositions for Supercapacitors with Improved Electrochemical Stability

Ni nanowires were first synthesized via a chemical method without surfactants or a magnetic field. A series of nickel sulfide nanowires (Ni₃S₂–Ni, Ni₃S₂–NiS–Ni, and Ni₃S₂–NiS) have been successfully prepared by a controlled sacrificial template route based on the conductive Ni nanowire template. Electrochemical characterizations indicate that Ni₃S₂–NiS nanowires present superior redox reactivity with a high specific capacitance of 1077.3 F g^–1 at 5 A g^–1. Besides, its specific capacitance can remain about 76.3% after 10 000 cycles at 20 A g^–1. On the contrary, the nickel-preserving sulfide nanowires (Ni₃S₂–Ni and Ni₃S₂–NiS–Ni) deliver enhanced cycling stability as 100% of the initial specific capacitance of Ni₃S₂–Ni is retained after 10 000 cycles. The outstanding electrochemical stability can be attributed to the interaction between nickel sulfides and the conductive nickel nanowires

Bromo-Substituted Diketopyrrolopyrrole Derivative with Specific Targeting and High Efficiency for Photodynamic Therapy

Novel photosensitizers with high reactive oxygen species generation and precise targeting to tumors are crucial for photodynamic therapy (PDT). Here, a bromo-substituted diketopyrrolopyrrole derivative (2,5-bis­(6-bromohexyl)-3,6-bis­(5-bromothiophene-2-yl)-2,5-dihydropyrrolo­[3,4-<i>c</i>]­pyrrole-1,4-dione)-grafted hyaluronic acid is synthesized, which presents excellent targeting and PDT efficiency both in vitro and in vivo

Template Synthesis of Shape-Tailorable NiS₂ Hollow Prisms as High-Performance Supercapacitor Materials

Uniform NiS₂ hollow nanoprisms have been controllably synthesized by a facial sacrificial template method including two-step refluxed reactions. The morphology of the hollow NiS₂ prisms can be easily tailored by the low cost nickel complex template. With unique hollow structure, efficient electron, and ion transport pathway as well as single crystal structure, the NiS₂ hollow prisms electrode exhibits excellent pseudocapacitive performance in LiOH electrolyte. It can deliver a specific capacitance of 1725 F g^–1 at a current density of 5 A g^–1 and 1193 F g^–1 even at a current density of 40 A g^–1. Furthermore, the materials also present an amazing cycling stability, that is, the specific capacitance can increase from 1367 F g^–1 to 1680 F g^–1 after 10 000 cycles of charge–discharge at the current density of 20 A g^–1

3D Graphene Foam as a Monolithic and Macroporous Carbon Electrode for Electrochemical Sensing

Graphene, a single-atom-thick monolayer of sp² carbon atoms perfectly arranged in a honeycomb lattice, is an emerging sensing material because of its extraordinary properties, such as exceptionally high specific surface area, electrical conductivity, and electrochemical potential window. In this study, we demonstrate that three-dimensional (3D), macroporous, highly conductive, and monolithic graphene foam synthesized by chemical vapor deposition represents a novel architecture for electrochemical electrodes. Being employed as an electrochemical sensor for detection of dopamine, 3D graphene electrode exhibits remarkable sensitivity (619.6 μA mM^–1 cm^–2) and lower detection limit (25 nM at a signal-to-noise ratio of 5.6), with linear response up to ∼25 μM. And the oxidation peak of dopamine can be easily distinguished from that of uric acid – a common interferent to dopamine detection. We envision that the graphene foam provides a promising platform for the development of electrochemical sensors as well as other applications, such as energy storage and conversion

Diketopyrrolopyrrole-Based Photosensitizers Conjugated with Chemotherapeutic Agents for Multimodal Tumor Therapy

For synergistic cancer therapy, it is highly desirable to devise a single multifunctional agent to combine photodynamic therapy (PDT), photothermal therapy (PTT), and chemotherapy, which is soluble and excitable at low irradiation, as well as able to selectively target tumors and achieve high efficacy. Toward this ambition, here the chemotherapy drugs chlorambucil (Cb), and all trans retinoic acid (ATRA) are covalently conjugated onto a small dye molecule diketopyrrolopyrrole (DPP-Cb and DPP-ATRA). The soluble nanoparticles (NPs) of DPP-Cb and DPP-ATRA formed by reprecipitation can selectively accumulate in tumors, release chemotherapy drugs under acidic conditions, and exhibit efficient reactive oxygen species (ROS) generation and photothermal conversion under the irradiation of a low power xenon lamp (40 mW/cm²). We show <i>in vitro</i> and <i>in vivo</i> that both NPs can effectively kill cancer cells and suppress cancer growth at a low dose (0.4 mg/kg)

Fe₂O₃/SnSSe Hexagonal Nanoplates as Lithium-Ion Batteries Anode

Novel two-dimensional (2D) Fe₂O₃/SnSSe hexagonal nanoplates were prepared from hot-inject process in oil phase. The resulted hybrid manifests a typical 2D hexagonal nanoplate morphology covered with thin carbon layer. Serving as anode material of lithium-ion battery (LIB), the Fe₂O₃/SnSSe hybrid delivers an outstanding capacity of 919 mAh g^–1 at 100 mA g^–1 and a discharge capacity of 293 mAh g^–1 after 300 cycles at the current density of 5 A g^–1. Compared with pristine SnSSe nanoplates, the Fe₂O₃/SnSSe hybrid exhibits both higher capacity and better stability. The enhanced performance is mainly attributed to the 2D substrate together with the synergistic effects offered by the integration of SnSSe with Fe₂O₃. The 2D Fe₂O₃/SnSSe hybrid can afford highly accessible sites and short ion diffusion length, which facilitate the ion accessibility and improves the charge transport. The novel structure and high performance demonstrated here afford a new way for structural design and the synthesis of chalcogenides as LIB anodes

3D Printed Microfluidic Device with Microporous Mn₂O₃‑Modified Screen Printed Electrode for Real-Time Determination of Heavy Metal Ions

Fabricating portable devices for the determination of heavy metal ions is an ongoing challenge. Here, a 3D printing approach was adopted to fabricate a microfluidic electrochemical sensor with the desired shape in which the model for velocity profiles in microfluidic cells was built and optimized by the finite element method (FEM). The electrode in the microfluidic cell was a flexible screen-printed electrode (SPE) modified with porous Mn₂O₃ derived from manganese containing metal–organic framework (Mn-MOF). The microfluidic device presented superior electrochemical detection properties toward heavy metal ions. The calibration curves at the modified SPE for Cd­(II) and Pb­(II) covered two linear ranges varying from 0.5 to 8 and 10 to 100 μg L^–1, respectively. The limits of detection were estimated to be 0.5 μg L^–1 for Cd­(II) and 0.2 μg L^–1 for Pb­(II), which were accordingly about 6 and 50 times lower than the guideline values proposed by the World Health Organization. Furthermore, the microfluidic device was connected to iPad via a USB to enable real-time household applications. Additionally, the sensing system exhibited a better stability and reproducibility compared with traditional detecting system which offered a promising prospect for the detection of heavy metal ions especially in household and resource-limited occasions

Monitoring Dynamic Cellular Redox Homeostasis Using Fluorescence-Switchable Graphene Quantum Dots

Monitoring cellular redox homeostasis is critical to the understanding of many physiological functions ranging from immune reactions to metabolism, as well as to the understanding of pathological development ranging from tumorigenesis to aging. Nevertheless, there is currently a lack of appropriate probes for this ambition, which should be reversibly, sensitively, and promptly responsive to a wide range of physiological oxidants and reductants. In this work, a redox-sensitive fluorescence-switchable probe is designed based on graphene quantum dots (GQDs) functionalized with a chelated redox Fe²⁺/Fe³⁺ couple. The underlying mechanism is investigated and discussed. The high sensitivity and fast response are attributable to the fact that the GQD’s photoluminescence is highly sensitive to photon-induced electron transfer because of its ultrasmall size and associated prominent quantum confinement effect. Also taking advantages of GQDs’ excellent photostability, biocompatibility, and readiness for cell uptake, our reversibly tunable fluorescence probe is employed to monitor in real time the triggered dynamic change of the intracellular redox state. This addition to the limited arsenal of available redox probes shall be useful to the still poorly understood redox biology, as well as for monitoring environment or chemical processes involving redox reactions