Self-Assembled Graphene/Carbon Nanotube Hybrid Films for Supercapacitors

Stable aqueous dispersions of polymer-modified graphene sheets were prepared via in situ reduction of exfoliated graphite oxides in the presence of cationic poly(ethyleneimine) (PEI). The resultant water-soluble PEI-modified graphene sheets were then used for sequential self-assembly with acid-oxidized multiwalled carbon nanotubes, forming hybrid carbon films. These hybrid films were demonstrated to possess an interconnected network of carbon structures with well-defined nanopores to be promising for supercapacitor electrodes, exhibiting a nearly rectangular cyclic voltammogram even at an exceedingly high scan rate of 1 V/s with an average specific capacitance of 120 F/g

Highly Efficient Metal-Free Growth of Nitrogen-Doped Single-Walled Carbon Nanotubes on Plasma-Etched Substrates for Oxygen Reduction

We have for the first time developed a simple plasma-etching technology to effectively generate metal-free particle catalysts for efficient metal-free growth of undoped and/or nitrogen-doped single-walled carbon nanotubes (CNTs). Compared with undoped CNTs, the newly produced metal-free nitrogen-containing CNTs were demonstrated to show relatively good electrocatalytic activity and long-term stability toward oxygen reduction reaction (ORR) in an acidic medium. Owing to the highly generic nature of the plasma etching technique, the methodology developed in this study can be applied to many other substrates for efficient growth of metal-free CNTs for various applications, ranging from energy related to electronic and to biomedical systems

Polyelectrolyte Functionalized Carbon Nanotubes as Efficient Metal-free Electrocatalysts for Oxygen Reduction

Having a strong electron-withdrawing ability, poly(diallyldimethylammonium chloride) (PDDA) was used to create net positive charge for carbon atoms in the nanotube carbon plane via intermolecular charge transfer. The resultant PDDA functionalized/adsorbed carbon nanotubes (CNTs), either in an aligned or nonaligned form, were demonstrated to act as metal-free catalysts for oxygen reduction reaction (ORR) in fuel cells with similar performance as Pt catalysts. The adsorption-induced intermolecular charge-transfer should provide a general approach to various carbon-based efficient metal-free ORR catalysts for oxygen reduction in fuel cells, and even new catalytic materials for applications beyond fuel cells

Data_Sheet_1_Boosting Oxygen Reduction Performance of Manganese Oxide in Alkaline Media by Three-Dimensional Highly Ordered Conductive Porous Framework.pdf

MnO2 has been widely used as an alternative candidate for oxygen reduction reaction owing to its abundance, low cost, and environmental compatibility. However, bulk MnO2 as electrocatalysts is still suffering from serious active sites agglomeration and poor conductivity, resulting in low utilization of catalysts and sluggish reaction kinetics. In view of this, we fabricated a 3D highly ordered porous MnO2@Ni-pc nanocomposite and significantly enhance ORR performance of MnO2 with high onset potential of 1.04 V and half-wave potential of 0.89 V as well as a large limiting current density of 4.07 mA cm−2, being even comparable to the commercial Pt/C. This nano-engineering technique is suitable for various catalysts that can be attached onto the 3D highly ordered porous framework, which provides new opportunities in designing electrode structures to boost the performance of bulk materials.</p

Vertically Aligned Carbon Nanotube Arrays Co-doped with Phosphorus and Nitrogen as Efficient Metal-Free Electrocatalysts for Oxygen Reduction

Using a mixture of ferrocene, pyridine, and triphenylphosphine as precursors for injection-assisted chemical vapor deposition (CVD), we prepared the first vertically aligned multiwalled carbon nanotube array co-doped with phosphorus (P) and nitrogen (N) with a relatively high P-doping level (designated as PN-ACNT). We have also demonstrated the potential applications of the resultant PN-ACNTs as high-performance electrocatalysts for the oxygen reduction reaction (ORR). PN-ACNT arrays were shown to exhibit a high ORR electrocatalytic activity, superb long-term durability, and good tolerance to methanol and carbon monoxide, significantly outperforming their counterparts doped with P (P-ACNT) or N (N-ACNT) only and even comparable to the commercially available Pt–C catalyst (45 wt % Pt on Vulcan XC-72R; E-TEK) due to a demonstrated synergetic effect arising from the co-doping of CNTs with both P and N

Biocompatible Graphene Oxide-Based Glucose Biosensors

This letter demonstrates that a novel, highly efficient enzyme electrode can be directly obtained using covalent attachment between carboxyl acid groups of graphene oxide sheets and amines of glucose oxidase. The resulting biosensor exhibits a broad linear range up to 28 mM·mm−2 glucose with a sensitivity of 8.045 mA·cm−2·M−1. The glucose oxidase-immobilized graphene oxide electrode also shows a reproducibility and a good storage stability, suggesting potentials for a wide range of practical applications. The biocompatibility of as-synthesized graphene oxide nanosheets with human cells, especially retinal pigment epithelium (RPE) cells, was investigated for the first time in the present work. Microporous graphene oxide exhibits good biocompatibility and has potential advantages with respect to cell attachment and proliferation, leading to opportunities for using graphene-based biosensors for the clinical diagnosis

Data_Sheet_1_Commercial Fiber Products Derived Free-Standing Porous Carbonized-Membranes for Highly Efficient Solar Steam Generation.pdf

Herein, the free-standing porous carbonized-membranes (CMs) derived from a series of commercial fiber products including airlaid papers, cellulose papers and cleanroom wipers by one-step carbonization at 160°C have for the first time explored as independent solar absorbers to realize highly efficient solar steam generation. These newly-developed CMs not only exhibit the strong absorption (low reflectance) and rapid transport of vapor/liquid, but also possess the restricted thermal diffusion. All these merits render CMs with excellent evaporation performance for solar steam generation. Particularly, the CMs derived from carbonized cellulose papers (CCPs) exhibits the best performance, which affords the water evaporation rate of 0.959 kg·m−2·h−1 and the energy conversion efficiency of 65.8% under 1 kW·m−2 solar illumination, due to the higher light absorption (92.20%) and lower thermal conductivity (0.031 W·m-1·K-1) competing favorable with those of the Au nanoparticles-loaded airlaid papers (Au-APs, 0.856 kg·m−2·h−1, 58.7%). Due to the low-cost, recyclability and highly efficient evaporation performance, the CMs, especially the CCPs, show great potential as solar absorbers for large-scale application of solar steam generation.</p

Effective Dual Polysulfide Rejection by a Tannic Acid/Fe^III Complex-Coated Separator in Lithium–Sulfur Batteries

The solubility behaviour of polysulfides in electrolyte solutions is a major bottleneck prior to the practical application of the lithium–sulfur battery. To address this issue, we fabricate a tannic acid/Fe^III complex-coated polypropylene (PP) separator (TA/Fe^III-PP separator) via a simple, fast, and green method. Benefiting from dual-confinement effects based on Lewis acid–base interactions between Fe^III and polysulfides as well as the dipole–dipole interactions between rich phenol groups and polysulfides, the migration of polysulfides is effectively suppressed. Meanwhile, the porous structure of the PP separator is not destroyed by an additional coating layer. Thus, the TA/Fe^III-PP separator can retain rapid lithium ion transport, eventually leading to a significant improvement in both the discharge capacity and rate performance of the corresponding lithium–sulfur cells. The cell with the TA/Fe^III-PP separator presents a low capacity fade of 0.06% per cycle over 1000 cycles at 2.0 C, along with a high Coulombic efficiency of >97% over 300 cycles at 0.5 C. With respect to the one with the bare PP separator, the cell with the TA/Fe^III-PP separator exhibits a 1.7-fold increase in the discharge capacity at 3.0 C. The proposed simple and economical approach shows great potential in constructing advanced separators to retard the shuttle effect of polysulfides for lithium–sulfur batteries

Organo-Soluble Chiral Thiol-Monolayer-Protected Gold Nanorods

Here, we report the synthesis and characterization of organo-soluble chiral thiol-monolayer-protected gold nanorods. The resulting gold nanorods respectively covered with two opposite enantiomers via the strong covalent Au−S linkage were found to not only be stable in both organic media and solid state, but also show optical activity. Their circular dichroism (CD) spectra exhibited a mirror image relationship, indicating that enantiomeric thiol surfactant on gold surface can produce the corresponding enantiomeric gold nanorods. The densely packed azobenzene thiol monolayer on gold surface exhibited a photoresponsive behavior upon irradiation with 254 nm light instead of 365 nm light, which was found to have an effect on plasmonic absorption of gold nanorods

Soluble P3HT-Grafted Graphene for Efficient Bilayer−Heterojunction Photovoltaic Devices

CH2OH-terminated regioregular poly(3-hexylthiophene) (P3HT) was chemically grafted onto carboxylic groups of graphene oxide (GO) via esterification reaction. The resultant P3HT-grafted GO sheets (G-P3HT) are soluble in common organic solvents, facilitating the structure/property characterization and the device fabrication by solution processing. The covalent linkage and the strong electronic interaction between the P3HT and graphene moieties in G-P3HT were confirmed by spectroscopic analyses and electrochemical measurements. A bilayer photovoltaic device based on the solution-cast G-P3HT/C60 heterostructures showed a 200% increase of the power conversion efficiency (η = 0.61%) with respect to the P3HT/C60 counterpart under AM 1.5 illumination (100 mW/cm2)