Nickel foam-loaded Co-MOF@TiO2/MoS2 as electrode materials for dual-function devices for glucose detection and hydrogen evolution.

Dual-functional nanomaterial electrodes have the capability to satisfy the requirements for both sweat analysis and the hydrogen evolution reaction (HER), thereby enabling the integration of electrochemical sensing and hydrogen production. In this study, ZIF-67 cubes are synthesized on nickel foam (NF), while TiO2 is obtained through an annealing process. Subsequently, the ZIF-67@TiO2/MoS2 nanocomposite is fabricated on nickel foam via a hydrothermal method. This composite material exhibits exceptional photocatalytic properties and is also suitable for the detection of glucose in sweat. The glucose detection range spans from 10 nM to 10 mM with a sensitivity of 7.24 µA mM-1 cm-2 for a signal-to-noise ratio of 3 and a detection limit of 0.43 µM. Moreover, when utilized as a hydrogen evolution electrode, this material demonstrates a current density of 10 mA cm-2 at an overpotential of 118 mV, with a Tafel slope of 73 mV/dec. The synthesis process is both straightforward and economical. This research introduces a novel concept for the design of multifunctional chemical sensors.

Effect of point defects on the band alignment and transport properties of 1T-MoS2/2H-MoS2/1T-MoS2 heterojunctions.

Defects, which are an unavoidable component of the material preparation process, can have a significant impact on the properties of two-dimensional devices. In this work, we investigated theoretically the effects of different types and positions of point defects on band alignment and transport properties of metallic 1T-phase MoS2/semiconducting 2H-phase MoS2 junctions. We found that the Schottky barriers of junctions depend on the type of defects and their locations while showing anisotropic characteristics along the zigzag and armchair directions of 2H-phase MoS2. Moreover, defects in the central scattering region can generate local impurity states and introduce new transmission peaks, while defects at the interface do not generate impurity-state-related transmission peaks. Together, these defect-related peaks and Schottky barriers jointly affect the transport properties of the junctions. Understanding the complex behaviors of defects in devices can make the process of material preparation more efficient by avoiding harm.

Pure spin current in a cobalt phthalocyanine chain induced by the photogalvanic effect.

The development of methods for generating pure spin current at the molecular level is vital. In this work, we investigated how the spin-related photocurrent is produced in a cobalt phthalocyanine chain by the photogalvanic effect (PGE). Depending on how the magnetic moments of the left and right halves of the cobalt phthalocyanine chain are arranged, spin current can be generated. Both charge current and spin current are absent when the magnetic moments are arranged in parallel. Pure spin currents are generated when the magnetic moments are arranged in an antiparallel manner. Importantly, the pure spin current is robust to the polarization type and polarization angle. This characteristic results from the structure's charge density having spatial inversion symmetry but lacking that of the spin density.

Hybrid ZnO-graphene electrode with palladium nanoparticles on Ni foam and application to self-powered nonenzymatic glucose sensing.

A self-powered nonenzymatic glucose sensor electrode boasts the advantages of both a glucose sensor and fuel cell. Herein, an electrode composed of ZnO-graphene hybrid materials on nickel foam (NF) is prepared by electrodeposition of Pd NPs. The electrode is characterized systematically and the dependence of electrocatalytic oxidation of glucose on the concentrations of KOH and glucose, temperature, and potential limit in the anodic direction is investigated. The Pd/NF-ZnO-G electrode shows high catalytic activity, sensitivity, stability, and selectivity in glucose detection, as exemplified by an electrocatalytic glucose oxidation current of 222.2 mA cm-2 under alkaline conditions, high linearity in the glucose concentration range from 5 µM to 6 mM (R 2 = 0.98), and high sensitivity of 129.44 µA mM-1-1 cm-2. The Pd/NF-ZnO-G electrode which exhibits superior electrocatalytic activity under alkaline conditions has large potential in nonenzymatic glucose sensing and direct glucose fuel cells and is suitable for miniaturized self-powered nonenzymatic glucose sensing.

Electrodeposited Pd/graphene/ZnO/nickel foam electrode for the hydrogen evolution reaction.

Efficient electrocatalysts are crucial to water splitting for renewable energy generation. In this work, electrocatalytic hydrogen evolution from Pd nanoparticle-modified graphene nanosheets loaded on ZnO nanowires on nickel foam was studied in an alkaline electrolyte. The high electron mobility stems from the cylindrical ZnO nanowires and the rough surface on the graphene/ZnO nanowires increases the specific surface area and electrical conductivity. The catalytic activity arising from adsorption and desorption of intermediate hydrogen atoms by Pd nanoparticles improves the hydrogen evolution reaction efficiency. As a hydrogen evolution reaction (HER) catalyst, the Pd/graphene/ZnO/Ni foam (Pd/G/ZnO/NF) nanocomposite exhibits good stability and superior electrocatalytic activity. Linear sweep voltammetry (LSV) revealed an overpotential of -31 mV and Tafel slope of 46.5 mV dec-1 in 1 M KOH. The economical, high-performance, and environmentally friendly materials have excellent prospects in hydrogen storage and hydrogen production.

MnO2/ZnCo2O4 with binder-free arrays on nickel foam loaded with graphene as a high performance electrode for advanced asymmetric supercapacitors.

ZnCo2O4 nanosheets were successfully arrayed on a Ni foam surface with graphene using a hydrothermal method followed by annealing treatment; then MnO2 nanoparticles were electrodeposited on the ZnCo2O4 nanosheets to obtain a synthesized composite binder-free electrode named MnO2/ZnCo2O4/graphene/Ni foam (denoted as MnO2/ZnCo2O4/G/NF). After testing the binder-free composite electrode of MnO2/ZnCo2O4/G/NF via cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy testing, we found that it exhibited ultrahigh electrochemical properties, with a high specific areal capacitance of 3405.21 F g-1 under a current density of 2 A g-1, and wonderful cycling stability, with 91.2% retention after 5000 cycles. Moreover, an asymmetric supercapacitor (ASC) based on MnO2/ZnCo2O4/G/NF//G/NF was successfully designed. When tested, the as-designed ASC can achieve a maximum energy density of 46.85 W h kg-1 at a power density of 166.67 W kg-1. Finally, the ASC we assembled can power a commercial red LED lamp successfully for more than 5 min, which proves its practicability. All these impressive performances indicate that the MnO2/ZnCo2O4/graphene composite material is an outstanding electrode material for electrochemical capacitors.

Improving classification of mature microRNA by solving class imbalance problem.

MicroRNAs (miRNAs) are ~20-25 nucleotides non-coding RNAs, which regulated gene expression in the post-transcriptional level. The accurate rate of identifying the start sit of mature miRNA from a given pre-miRNA remains lower. It is noting that the mature miRNA prediction is a class-imbalanced problem which also leads to the unsatisfactory performance of these methods. We improved the prediction accuracy of classifier using balanced datasets and presented MatFind which is used for identifying 5' mature miRNAs candidates from their pre-miRNA based on ensemble SVM classifiers with idea of adaboost. Firstly, the balanced-dataset was extract based on K-nearest neighbor algorithm. Secondly, the multiple SVM classifiers were trained in orderly using the balance datasets base on represented features. At last, all SVM classifiers were combined together to form the ensemble classifier. Our results on independent testing dataset show that the proposed method is more efficient than one without treating class imbalance problem. Moreover, MatFind achieves much higher classification accuracy than other three approaches. The ensemble SVM classifiers and balanced-datasets can solve the class-imbalanced problem, as well as improve performance of classifier for mature miRNA identification. MatFind is an accurate and fast method for 5' mature miRNA identification.

Electrooxidation of formaldehyde based on nickel-palladium modified ordered mesoporous silicon.

Nickel and palladium nanoparticles were finely dispersed on ordered mesoporous silicon microchannels plate (MCP) by electroless plating. The structure and composition of the resulting Ni-Pd/Si MCP were characterized by scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDS). The electrocatalystic properties of Ni-Pd/Si MCP electrode for formaldehyde oxidation have been investigated by cyclic voltammetry. The results show that Ni-Pd/Si MCP has a higher catalytic activity and better steady-state behavior for formaldehyde oxidation. This may be attributed to the synergistic property of high dispersion of Nickel and Palladium nanoparticles and particular properties of mesoporous Si MCP. The present study shows a promising choice of Ni-Pd nanoparticles supported by mesoporous silicon as effective electrocatalyst for formaldehyde electrooxidation in alkaline medium. The results imply that the Ni-Pd/Si MCP nanocomposite has good potential application in formaldehyde fuel cells and sensors.

Preparation and electrochemistry of Pd-Ni/Si nanowire nanocomposite catalytic anode for direct ethanol fuel cell.

A new silicon-based anode suitable for direct ethanol fuel cells (DEFCs) is described. Pd-Ni nanoparticles are coated on Si nanowires (SiNWs) by electroless co-plating to form the catalytic materials. The electrocatalytic properties of the SiNWs and ethanol oxidation on the Pd-Ni catalyst (Pd-Ni/SiNWs) are investigated electrochemically. The effects of temperature and working potential limit in the anodic direction on ethanol oxidation are studied by cyclic voltammetry. The Pd-Ni/SiNWs electrode exhibits higher electrocatalytic activity and better long-term stability in an alkaline solution. It also yields a larger current density and negative onset potential thus boding well for its application to fuel cells.