Zheng Zeng

New nitrogen-rich azo-bridged porphyrin-conjugated microporous networks for high performance of gas capture and storage

A series of new conjugated microporous polymers (Azo-1, Azo-2 and Azo-3) based on a nitrogen-rich porphyrin building unit and an azo bond linkage were synthesized by KOH assisted condensation. These materials were characterized by Fourier transform infrared spectroscopy (FT-IR), solid-state 13C NMR, XPS, scanning electron microscopy (SEM), high-resolution transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and tested for gas (N2, CO2 and H2) adsorption. It was revealed that the azos presented the formation of porous polymer networks affording amorphous particles with rough surfaces and irregular morphology with excellent thermal stability under nitrogen conditions. The Brunauer–Emmett–Teller (BET) model of the N2 adsorption gave apparent surface area ranges of 520–675 m2 g−1. The results from non-local density functional theory (NL-DFT) calculations suggested a pore size distribution between 1.6 and 4.0 nm. The gas (CO2, H2) adsorption isotherms demonstrated outstanding CO2 uptake up to 17.5 wt% (3.98 mmol g−1 for Azo-2) and moderate H2 storage. The isosteric heats of adsorption (Qst) are high, with values of 36–37 kJ mol−1 for the azo polymers. Moreover, the azo-polymer networks exhibited excellent selectivity with CO2/N2 up to 64.3 for Azo-2 at 273 K/1 bar. It was suggested that the nitrogen-rich active sites of the polymers play an important role for CO2 capture and storage.

Protein Trapping in Plasmonic Nanoslit and Nanoledge Cavities: The Behavior and Sensing

A novel plasmonic nanoledge device was presented to explore the geometry-induced trapping of nanoscale biomolecules and examine a generation of surface plasmon resonance (SPR) for plasmonic sensing. To design an optimal plasmonic device, a semianalytical model was implemented for a quantitative analysis of SPR under plane-wave illumination and a finite-difference time-domain (FDTD) simulation was used to study the optical transmission and refractive index (RI) sensitivity. In addition, total internal reflection fluorescence (TIRF) imaging was used to visualize the migration of fluorescently labeled bovine serum albumin (BSA) into the nanoslits; and fluorescence correlation spectroscopy (FCS) was further used to investigate the diffusion of BSA in the nanoslits. Transmission SPR measurements of free prostate specific antigen (f-PSA), which is similar in size to BSA, were performed to validate the trapping of the molecules via specific binding reactions in the nanoledge cavities. The present study may facilitate further development of single nanomolecule detection and new nanomicrofluidic arrays for effective detection of multiple biomarkers in clinical biofluids.

A semi-analytical decomposition analysis of surface plasmon generation and the optimal nanoledge plasmonic device.

Surface plasmon resonance (SPR) of nanostructured thin metal films (so-called nanoplasmonics) has attracted intense attention due to its versatility for optical sensing and chip-based device integration. Understanding the underlying physics and developing applications of nanoplasmonic devices with desirable optical properties, e.g. intensity of light scattering and high refractive index (RI) sensitivity at the perforated metal film, is crucial for practical uses in physics, biomedical detection, and environmental monitoring. This work presents a semi-analytical model that enables decomposition and quantitative analysis of surface plasmon generation at a new complex nanoledge aperture structure under plane-wave illumination, thus providing insight on how to optimize plasmonic devices for optimal plasmonic generation efficiencies and RI sensitivity. A factor analysis of parameters (geometric, dielectric-RI, and incident wavelength) relevant to surface plasmon generation is quantitatively investigated to predict the surface plasmon polariton (SPP) generation efficiency. In concert with the analytical treatment, a finite-difference time-domain (FDTD) simulation is used to model the optical transmission spectra and RI sensitivity as a function of the nanoledge devices geometric parameters, and it shows good agreement with the analytical model. Further validation of the analytical approach is provided by fabricating subwavelength nanoledge devices and testing their optical transmission and RI sensitivity.

Frontiers in nano-architectured carbon–metal oxide electrodes for supercapacitance energy storage: a review

Supercapacitor (SC) is an energy storage technology that bridges the gap between conventional capacitors and rechargeable batteries. Emerging nano-architectured carbon–metal oxide composites are promising for electrode designs for supercapacitors due to their unique strategy utilizing electrochemical double-layer capacitance (EDLC) and pseudo-capacitance together in single cell to optimize the energy storage ability and electrochemical stability. In recent years, technologies of integrating different metal oxide into single-walled/multi-walled carbon nanotubes (CNTs), graphene/reduced graphene oxide (rGO) and carbon nanofiber (CNF) and/or carbon fiber paper (CFP) have been reported with the focus of the nano-architecture electrodes. This paper provides a review of the frontiers with respect to incorporation of metal oxides into the carbon nanomaterials for capacitive energy storage improvements. Several key performance parameters in terms of specific capacitance, energy density, power density and cyclic stability along with the challenges and design trends are discussed and summarized.

Magnetic Field‐Enhanced 4‐Electron Pathway for Well‐Aligned Co3O4/Electrospun Carbon Nanofibers in the Oxygen Reduction Reaction

The sluggish reaction kinetics of the oxygen reduction reaction (ORR) has been the limiting factor for fuel energy utilization, hence it is desirable to develop high-performance electrocatalysts for a 4-electron pathway ORR. A constant low-current (50 μA) electrodeposition technique is used to realize the formation of a uniform Co3 O4 film on well-aligned electrospun carbon nanofibers (ECNFs) with a time-dependent growth mechanism. This material also exhibits a new finding of mT magnetic field-induced enhancement of the electron exchange number of the ORR at a glassy carbon electrode modified with the Co3 O4 /ECNFs catalyst. The magnetic susceptibility of the unpaired electrons in Co3 O4 improves the kinetics and efficiency of electron transfer reactions in the ORR, which shows a 3.92-electron pathway in the presence of a 1.32 mT magnetic field. This research presents a potential revolution of traditional electrocatalysis by simply applying an external magnetic field on metal oxides as a replacement for noble metals to reduce the risk of fuel-cell degradation and maximize the energy output.

Nanoarchitectured electrodes for supercapacitance energy storage

Abstract A supercapacitor (SC) is an energy storage device that bridges the gap between conventional capacitors and rechargeable batteries. Emerging architectured nanomaterials are promising for electrode designs for supercapacitors (SCs) due to their unique strategies utilizing electrochemical double-layer capacitance (EDLC) or pseudo-capacitance or both to optimize the energy storage capability and electrochemical (EC) stability. This chapter presents recent advances in metal oxide and carbon-based nanomaterials for supercapacitance energy storage. First, a brief introduction of current SC technologies is given. After that, the research development on the nanoarchitectured carbon and carbon–metal oxide composites in recent years is summarized and classified with various carbon nanomaterials (CNMs). Finally, the advanced strategies of energy storage to increase key performance parameters in terms of specific surface area, specific capacitance, and cyclic stability along with the future challenges are discussed.

Magnetoreception of Photoactivated Cryptochrome 1 in Electrochemistry and Electron Transfer

Cryptochromes are flavoproteins whose photochemistry is important for crucial functions associated with phototropism and circadian clocks. In this report, we, for the first time, observed a magnetic response of the cryptochrome 1 (CRY1) immobilized at a gold electrode with illumination of blue light. These results present the magnetic field-enhanced photoinduced electron transfer of CRY1 to the electrode by voltammetry, exhibiting magnetic responsive rate constant and electrical current changes. A mechanism of the electron transfer, which involves photoinduced radicals in the CRY, is sensitive to the weak magnetic field; and the long-lived free radical FAD•– is responsible for the detected electrochemical Faradaic current. As a photoreceptor, the finding of a 5.7% rate constant change in electron transfer corresponding to a 50 μT magnetic field may be meaningful in regulation of magnetic field signaling and circadian clock function under an electromagnetic field.