Cobalt Phosphide Hollow Polyhedron as Efficient Bifunctional Electrocatalysts for the Evolution Reaction of Hydrogen and Oxygen

The development of efficient and low-cost hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts for renewable-energy conversion techniques is highly desired. A kind of hollow polyhedral cobalt phosphide (CoP hollow polyhedron) is developed as efficient bifunctional electrocatalysts for HER and OER templated by Co-centered metal–organic frameworks. The as-prepared CoP hollow polyhedron, which have large specific surface area and high porosity providing rich catalytic active sites, show excellent electrocatalytic performances for both HER and OER in acidic and alkaline media, respectively, with onset overpotentials of 35 and 300 mV, Tafel slopes of 59 and 57 mV dec^–1, and a current density of 10 mA cm^–2 at overpotentials of 159 and 400 mV for HER and OER, respectively, which are remarkably superior to those of particulate CoP (CoP particles) and comparable to those of commercial noble-metal catalysts. In addition, the CoP hollow polyhedron also show good durability after long-term operations

Charge Transfer Kinetics from Surface Plasmon Resonance Voltammetry

On the basis of a quantitative relationship between surface plasmon resonance signal and electrochemical current in the electrochemical surface plasmon resonance (EC-SPR), EC-SPR signal measures the semi-integral of faradaic current. We theoretically discussed the electrode potential and charge transfer kinetics to be determined from surface plasmon resonance voltammetry (or potential sweep EC-SPR) signals for the fully reversible, quasi-reversible, and irreversible redox reactions. The results indicated that the electroanalysis of EC-SPR signal is more straightforward than conventional electrochemical current. Then, we studied two model redox reactions of hexaammineruthenium chloride and 4-nitrotoluene, to obtain half wave potential of quasi-reversible redox reaction, transfer coefficient, and standard rate constant of irreversible redox reaction from EC-SPR signals

Facilitated Lithium Storage in MoS₂ Overlayers Supported on Coaxial Carbon Nanotubes

The discoveries of carbon and inorganic fullerene-like nanotubes with a wide spectra of possible applications have stimulated multi- and interdisciplinary research activities. In this paper, we prepared MoS2 overlayers supported on coaxial carbon nanotubes and investigated lithium storage/release properties in relation to their structural properties. The coaxial nanoarchitecture was successfully synthesized by a designed solution-phase route in the low temperature range, which was characterized by X-ray powder diffraction (XRD), high resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The reversible lithium-storage behaviors involved in the nanoarchitecture were elucidated by means of various techniques including galvanostatic methods, cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). A thorough investigation of the composition−structure−property relationships of the coaxial nanoarchitecture highlighted the importance of the underlying carbon nanotubes in improving the lithium storage/release properties of the MoS2 sheath through a unique synergy at the nanoscale. This work should be notably significant for the design of new multifunctional nanoarchitectures by the wet-chemistry process, applicable for energy conversion and storage of the future

Controllable Self-Assembly of CdTe/Poly(<i>N</i>-isopropylacrylamide−acrylic acid) Microgels in Response to pH Stimuli

The self-assembly of hybrid CdTe/poly(N-isopropylacrylamide−acrylic acid) [poly(NIPAM−AAc)] microgels was tunable in response to pH stimuli. The pH-dependent swelling behavior of the polymer microgels played an important role in the self-assembly processes. At pH 3.73, the fractal and dendritic patterns of CdTe/poly(NIPAM−AAc) were fabricated on a large scale, in which the dipole moment of CdTe provided a significant driving force. At pH 11.28, the microgels aggregated and amalgamated to form a porous film and phase separation occurred between the CdTe nanocrystals and poly(NIPAM−AAc). The combination of the physical and chemical properties of inorganic CdTe nanocrystals with those of organic smart polymers provides a new opportunity for controllable self-assembly

Controllable Self-Assembly of CdTe/Poly(<i>N</i>-isopropylacrylamide−acrylic acid) Microgels in Response to pH Stimuli

The self-assembly of hybrid CdTe/poly(N-isopropylacrylamide−acrylic acid) [poly(NIPAM−AAc)] microgels was tunable in response to pH stimuli. The pH-dependent swelling behavior of the polymer microgels played an important role in the self-assembly processes. At pH 3.73, the fractal and dendritic patterns of CdTe/poly(NIPAM−AAc) were fabricated on a large scale, in which the dipole moment of CdTe provided a significant driving force. At pH 11.28, the microgels aggregated and amalgamated to form a porous film and phase separation occurred between the CdTe nanocrystals and poly(NIPAM−AAc). The combination of the physical and chemical properties of inorganic CdTe nanocrystals with those of organic smart polymers provides a new opportunity for controllable self-assembly

Tipping points of marine phytoplankton to multiple environmental stressors

Please downloaded the codes.zip, model data.zip, and workflow output.zip. Extract the contents of these three files into one folder. Codes.zip contains R and python codes for this work. model data.zip contains data used for model building and analyses. workflow output.zip contains all raw data for analysis and visualization.  Please be free to contact me if you have any reviews, comments, or questions. https://www.researchgate.net/profile/Zhan-Ban/ [email protected] </p

DNA−Hemoglobin−Multiwalls Carbon Nanotube Hybrid Material with Sandwich Structure: Preparation, Characterization, and Application in Bioelectrochemistry

A novel multiwall carbon nanotubes (MWNTs)-based hybrid material with sandwich structure (DNA-Hb-MWNTs) was fabricated by alternative electrostatic assembly of hemoglobin (Hb) and DNA on MWNTs. TEM showed that such a nanocomposite behaved as an obvious core−shell structure. SEM proved the well-preserved 3-D structure of DNA-Hb-MWNTs assembled on an electrode. UV−vis and FTIR spectroscopy were used to monitor the assembly procession and also demonstrated that Hb had been sandwiched into DNA and MWNTs without denaturation. A pair of stable and well-defined redox peaks of Hb with a formal potential of about −0.298 V (vs Ag/AgCl) in a pH 6.0 phosphate buffer solution (PBS) were obtained at the DNA-Hb-MWNTs nanocomposite film-modified glassy carbon (GC) electrode (DNA-Hb-MWNT/GC electrode). Compared with the Hb-MWNTs/GC electrode, the DNA-Hb-MWNTs/GC electrode exhibited enhanced faradic current response, and the portion of the electroactive proteins had been greatly improved. Furthermore, the modified electrode also displayed good sensitivity, wide linear range, and long-term stability to the detection of hydrogen peroxide. Such an organized multicomponent biosensor platform may find wide potential applications in biosensors, biocatalysis, biomedical devices, and bioelectronics

Pt Nanoparticles Inserting in Carbon Nanotube Arrays: Nanocomposites for Glucose Biosensors

A facile strategy has been developed to prepare carbon nanotubes loading Pt nanoparticle (Pt-CNT) composites. The method involves the polymerization reaction of glucose and the reduction deposition of a platinum source in the pores of anodic alumina membranes (AAMs) under hydrothermal conditions. The Pt-CNT nanocomposites can be obtained through the subsequent carbonization and removal of the AAM template. Through transmission electron microscopy and field-emission scanning electron microscopy, it is observed that the nanocomposites possess a stable hierarchical structure, in which the Pt nanoparticles are uniformly entrapped on the surface of CNTs. Additionally, the Pt-CNT nanocomposites contain large amounts of oxygen-rich groups that are beneficial to improving its solubility in water and biocompatibility for retaining the bioactivity of glucose oxidase. The nanocomposites electrode is successfully used as a sensitively amperometric sensor for low-potential determination of H2O2. The Pt-CNT-based glucose biosensor is fabricated by mixing the composites with the glucose oxidase, displaying a wide linear calibration range nearly 3 orders of magnitude of glucose concentrations (0.16−11.5 mM) and a low detection limit of 0.055 mM. Furthermore, the biosensor exhibits some other excellent characteristics, such as high sensitivity and selectivity, short response time, and long-term stability

Self-Phosphorylating Deoxyribozyme Initiated Cascade Enzymatic Amplification for Guanosine-5′-triphosphate Detection

The self-phosphorylating deoxyribozymes identified by in vitro selection can catalyze their own phosphorylation by utilizing phosphate donor guanosine-5′-triphosphate (GTP) which plays a critical role in a majority of cellular processes. On the basis of the unique properties of self-phosphorylating deoxyribozymes, we report a novel GTP sensor coupled with λ exonuclease cleavage reaction and nicking enzyme assisted fluorescence signal amplification process. The deoxyribozymes with special catalytic and structural characteristics display good stability compared to protein and RNA enzymes. We combined these properties with enzymatic recycling cleavage strategy to build a sensor which produced enhanced fluorescence signal. Sensitive and selective detection of GTP was successfully realized with the well-designed deoxyribozyme-based sensing platform by taking advantage of the self-phosphorylating ability of the kinase deoxyribozyme, efficient digestion capacity of λ exonuclease, and enzymatic recycling amplification of nicking enzyme. The method not only provides a platform for detecting GTP but also shows great potential in analyzing a variety of targets by combining deoxyribozymes with signal amplification strategy

Reusable and Dual-Potential Responses Electrogenerated Chemiluminescence Biosensor for Synchronously Cytosensing and Dynamic Cell Surface N‑Glycan Evaluation

A novel reusable and dual-potential responsive electrogenerated chemiluminescence (ECL) biosensor was fabricated for synchronous detection of cancer cells and their surface N-glycan. In this strategy, a cancer cell recognized aptamer hybridized with a capture DNA was immobilized on electrochemically reduced MoS₂ nanosheets, and Ru­(phen)₃²⁺ as ECL probes was intercalated into the grooves of the double-strand DNA. In the presence of target cells, the capture DNA and Ru­(phen)₃²⁺ were released from the electrode interface owing to the specific interaction between cancer cells and the aptamer. Meanwhile, concanavalin A (Con A), a mannose binding protein, and a conjugated gold nanoparticle modified graphite-C₃N₄ (Con A@Au-C₃N₄) was used as a negative ECL nanoprobe and applied for the cell surface N-glycan evaluation owing to the excellent ECL properties of g-C₃N₄ at negative potential. The cytosensing and cell surface N-glycan evaluation could be simultaneously realized with high sensitivity and excellent selectivity based on the ratio of ECL intensity between the negative potential and positive potential (ΔECL_n/ΔECL_p), avoiding the traditional routing cell counting procedures. Moreover, the aptamer modified electrode can be regenerated in the presence of capture DNA solutions for cyclic utilization. As a proof-of-concept, the ECL cytosensor showed excellent performances for the analysis of the MCF-7 cancer cell and its surface N-glycan evaluation in human serum samples. The reusable and dual potential response ECL biosensor endows a feasibility tool for clinical diagnosis and drug screening especially in complex biological systems