Yanglong Hou

Synthesis, Functionalization, and Biomedical Applications of Multifunctional Magnetic Nanoparticles

Synthesis of multifunctional magnetic nanoparticles (MFMNPs) is one of the most active research areas in advanced materials. MFMNPs that have magnetic properties and other functionalities have been demonstrated to show great promise as multimodality imaging probes. Their multifunctional surfaces also allow rational conjugations of biological and drug molecules,making it possible to achieve target-specific diagnostics and therapeutics.This review fi rst outlines the synthesis of MNPs of metal oxides and alloy sand then focuses on recent developments in the fabrication of MFMNPs of core/shell, dumbbell, and composite hybrid type. It also summarizes the general strategies applied for NP surface functionalization. The review further highlights some exciting examples of these MFMNPs for multimodality imaging and for target-specific drug/gene delivery applications.

Synthesis of phosphorus-doped graphene and its multifunctional applications for oxygen reduction reaction and lithium ion batteries.

We develop a simple and economical thermal annealing method for the synthesis of phosphorus-doped graphene, which exhibits remarkable electrocatalytic activity towards the oxygen reduction reaction and enhances the electrochemical performance as an anode material for lithium ion batteries. The experimental results suggest the significant role of phosphorus atoms in graphene.

Graphene-based nanocomposites for energy storage and conversion in lithium batteries, supercapacitors and fuel cells

Due to their unique properties, together with their ease of synthesis and functionalization, graphene-based materials have been showing great potential in energy storage and conversion. These hybrid structures display excellent material characteristics, including high carrier mobility, faster recombination rate and long-time stability. In this review, after a short introduction to graphene and its derivatives, we summarize the recent advances in the synthesis and applications of graphene and its derivatives in the fields of energy storage (lithium ion, lithium–air, lithium–sulphur batteries and supercapacitors) and conversion (oxygen reduction reaction for fuel cells). This article further highlights the working principles and problems hindering the practical applications of graphene-based materials in lithium batteries, supercapacitors and fuel cells. Future research trends towards new methodologies to the design and the synthesis of graphene-based nanocomposite with unique architectures for electrochemical energy storage and conversion are also proposed.

Nickel sulfide/nitrogen-doped graphene composites: phase-controlled synthesis and high performance anode materials for lithium ion batteries.

Phase-controlled nickel sulfide (Ni3 S4 and NiS1.03 ) nanoparticle (NP)/nitrogen-doped graphene (NG) composites are prepared through a facile one-pot hydrothermal process. The composites show ultrahigh capacity retentions of 98.87% and 95.94% for Ni3 S4 /NG and NiS1.03 /NG electrodes, respectively, as anode materials for lithium ion batteries.

Multifunctional Co3S4/Graphene Composites for Lithium Ion Batteries and Oxygen Reduction Reaction

Cobalt sulfide is a good candidate for both lithium ion batteries (LIBs) and cathodic oxygen reduction reaction (ORR), but low conductivity, poor cyclability, capacity fading, and structural changes hinder its applications. The incorporation of graphene into Co3S4 makes it a promising electrode by providing better electrochemical coupling, enhanced conductivity, fast mobility of ions and electrons, and a stabilized structure due to its elastic nature. With the objective of achieving high-performance composites, herein we report a facile hydrothermal process for growing Co3S4 nanotubes (NTs) on graphene (G) sheets. Electrochemical impedance spectroscopy (EIS) verified that graphene dramatically increases the conductivity of the composites to almost twice that of pristine Co3S4. Electrochemical measurements indicated that the as-synthesized Co3S4/G composites exhibit good cyclic stability and a high discharge capacity of 720 mA h g(-1) up to 100 cycles with 99.9% coulombic efficiency. Furthermore, the composites react with dissolved oxygen in the ORR by four- and two-electron mechanisms in both acidic and basic media with an onset potential close to that of commercial Pt/C. The stability of the composites is much higher than that of Pt/C, and exhibit high methanol tolerance. Thus, these properties endorse Co3 S4 /G composites as auspicious candidates for both LIBs and ORR.

Hybrid of Co3Sn2@Co Nanoparticles and Nitrogen-Doped Graphene as a Lithium Ion Battery Anode

A facile strategy was designed for the fabrication of hybrid of Co3Sn2@Co nanoparticles (NPs) and nitrogen-doped graphene (NG) sheets through a hydrothermal synthesis, followed by annealing process. Core-shell architecture of Co3Sn2@Co pin on NG is designed for the dual encapsulation of Co3Sn2 with adaptable ensembles of Co and NG to address the structural and interfacial stability concerns facing tin-based anodes. In the resulted unique architecture of Co3Sn2@Co-NG hybrid, the sealed cobalt cover prevents the direct exposer of Sn with electrolyte because of encapsulated structure and keeps the structural and interfacial integrity of Co3Sn2. However, the elastically strong, flexible and conductive NG overcoat accommodates the volume changes and therefore brings the structural and electrical stabilization of Co3Sn2@Co NPs. As a result, Co3Sn2@Co-NG hybrid exhibits extraordinary reversible capacity of 1615 mAh/g at 250 mA/g after 100 cycles with excellent capacity retention of 102%. The hybrid bears superior rate capability with reversible capacity of 793.9 mAh/g at 2500 mA/g and Coulombic efficiency nearly 100%.

Solvothermal reduction synthesis and characterization of superparamagnetic magnetite nanoparticlesElectronic supplementary information (ESI) available: size distributions of samples modified with TOPO + PVP, HDA + PVP, and PVP only. See http://www.rsc.org/suppdata/jm/b3/b305526d/

Magnetite nanoparticles were prepared through a solvothermal reduction approach in the presence of ethylene glycol, oleic acid and trioctylphosphine oxide or hexadecylamine. The size of the magnetite nanoparticles can be controlled easily through tailoring surfactants in the system. Transmission electron microscopy images indicate that the average sizes of magnetite nanoparticles are 8 and 11 nm, depending on the surfactant. The far IR spectra further demonstrate that the products are magnetite instead of hematite. Superparamagnetism and the effect of σ-donor and π-acceptor type surfactants on the magnetic properties of the nanoscale materials have been investigated.

Multifunctional Fe5C2 Nanoparticles: A Targeted Theranostic Platform for Magnetic Resonance Imaging and Photoacoustic Tomography‐Guided Photothermal Therapy

Fe5 C2 NPs exhibit a high contrast in magnetic resonance imaging (MRI), superior photoacoustic tomography improvements, and efficient photothermal therapy (PTT) due to their unique core/shell structure, with a magnetic core and carbon shell. By conjugating a new class of affinity proteins (ZHER2:342), they can target to tumor cells with low cytotoxicity, and kill them through laser irritation. It is also possible to ablate tumors under guidance by MRI and PTT without noticeable side effects.

Rational Design of Si/SiO2@Hierarchical Porous Carbon Spheres as Efficient Polysulfide Reservoirs for High‐Performance Li–S Battery

Integrated design of Si/SiO2 @hierar-chical porous carbon spheres is made and used as efficient polysulfide reservoir for enhancing lithium-sulfur battery (LSB) in terms of capacity, rate ability, and cycling stability via combined chemical and physical effects.

A porous nitrogen and phosphorous dual doped graphene blocking layer for high performance Li–S batteries

Conductive confinement of sulfur and polysulfides via carbonaceous blocking layers can simultaneously address the issues of low conductivity, volume expansion of sulfur during the charge/discharge process and the polysulfide shuttling effect in lithium–sulfur (Li–S) batteries. Herein, a conductive and porous nitrogen and phosphorus dual doped graphene (p-NP-G) blocking layer is prepared via a thermal annealing and subsequent hydrothermal reaction route. The doping levels of N and P in p-NP-G as measured by X-ray photoelectron spectroscopy are ca. 4.38% and ca. 1.93%, respectively. The dual doped blocking layer exhibits higher conductivity than N or P single doped blocking layers. More importantly, density functional theory (DFT) calculations demonstrate that P atoms and –P–O groups in the p-NP-G layer offer stronger adsorption of polysulfides than the N species. The electrochemical evaluation results illustrate that the p-NP-G blocking layer can deliver superior initial capacity (1158.3 mA h g−1 at a current density of 1C), excellent rate capability (633.7 mA h g−1 at 2C), and satisfactory cycling stability (ca. 0.09% capacity decay per cycle), which are better than those of the N or P single doped graphene. This work suggests that this synergetic combination of conductive and adsorptive confinement strategies induced by the multi-heteroatom doping scheme is a promising approach for developing high performance Li–S batteries.