Yanhong Lu

Graphene-based Li-ion hybrid supercapacitors with ultrahigh performance

There is a growing demand for hybrid supercapacitor systems to overcome the energy density limitation of existing-generation electric double layer capacitors (EDLCs), leading to next generation-II supercapacitors with minimum sacrifice in power density and cycle life. Here, an advanced graphene-based hybrid system, consisting of a graphene-inserted Li4Ti5O12 (LTO) composite anode (G-LTO) and a three-dimensional porous graphene-sucrose cathode, has been fabricated for the purpose of combining both the benefits of Li-ion batteries (energy source) and supercapacitors (power source). Graphene-based materials play a vital role in both electrodes in respect of the high performance of the hybrid supercapacitor. For example, compared with the theoretical capacity of 175 mA·h·g−1 for pure LTO, the G-LTO nanocomposite delivered excellent reversible capacities of 207, 190, and 176 mA·h·g−1 at rates of 0.3, 0.5, and 1 C, respectively, in the potential range 1.0–2.5 V vs. Li/Li+; these are among the highest values for LTO-based nanocomposites at the same rates and potential range. Based on this, an optimized hybrid supercapacitor was fabricated following the standard industry procedure; this displayed an ultrahigh energy density of 95 Wh·kg−1 at a rate of 0.4 C (2.5 h) over a wide voltage range (0–3 V), and still retained an energy density of 32 Wh·kg−1 at a high rate of up to 100 C, equivalent to a full discharge in 36 s, which is exceptionally fast for hybrid supercapacitors. The excellent performance of this Li-ion hybrid supercapacitor indicates that graphene-based materials may indeed play a significant role in next-generation supercapacitors with excellent electrochemical performance.

A Flexible and High‐Voltage Internal Tandem Supercapacitor Based on Graphene‐Based Porous Materials with Ultrahigh Energy Density

Pursuing higher working voltage and packaged energy density, an internal tandem supercapacitor has been successfully designed and fabricated based on graphene-based porous carbon hybrid material. Compared with the packaged energy density of 27.2 Wh kgcell (-1) and working voltage of 3.5 V using EMIMBF4 electrolyte for the conventional single-cell supercapacitor, the internal tandem device with the same material achieves a much higher working voltage of 7 V as well as a significantly improved energy density of 36.3 Wh kgcell (-1) (increased by 33%), which is also about 7 times of that of the state-of-art commercial supercapacitors. A flexible internal tandem device is also designed and fabricated and demonstrated similar excellent performance.

DNA electrochemical sensor based on an adduct of single-walled carbon nanotubes and ferrocene

A novel electrochemical sandwich-type gene sensing system was designed by using a DNA probe (DNA-probe1) immobilized on a gold electrode, the target DNA, and another DNA probe (DNA-probe2) conjugated on a single-walled carbon nanotubes/ferrocene (Fc–SWNT) adduct. In this sandwich-type gene-sensing electrode, the Fc–SWNT adduct could significantly amplify the electrochemical response of the reduction of H2O2. The target DNA could be detected selectively and sensitively based on the much enhanced electrochemical catalytic property of the Fc–SWNT adduct toward H2O2 reduction.

High activity of hot electrons from bulk 3D graphene materials for efficient photocatalytic hydrogen production

Design and synthesis of efficient photocatalysts for hydrogen production via water splitting are of great importance from both theoretical and practical viewpoints. Many metal-based semiconductors have been explored for this purpose in recent decades. Here, for the first time, an entirely carbon-based material, bulk three-dimensionally cross-linked graphene (3DG), has been developed as a photocatalyst for hydrogen production. It exhibits a remarkable hydrogen production rate of 270 μmol·h−1·gcat−1 under full-spectrum light via a hot/free electron emission mechanism. Furthermore, when combined with the widely used semiconductor TiO2 to form a TiO2/3DG composite, it appears to become a more efficient hydrogen production photocatalyst. The composite achieves a production rate of 1,205 μmol·h−1·gcat−1 under ultraviolet–visible (UV–vis) light and a 7.2% apparent quantum efficiency at 350 nm due to the strong synergetic effects between TiO2 and 3DG.

What are the practical limits for the specific surface area and capacitance of bulk sp 2 carbon materials

The possible practical limits for the specific surface area and capacitance performance of bulk sp2 carbon materials were investigated experimentally and theoretically using a variety of carbon materials. We find the limit for the specific surface area to be 3500–3700 m2 g−1, and based on this, the corresponding best capacitance was predicted for various electrolyte systems. A model using an effective ionic diameter for the electrolyte ions was proposed and used to calculate the theoretical capacitance. A linear dependence of experimental capacitance versus effective specific surface area of various sp2 carbon materials was obtained for all studied ionic liquid, organic and aqueous electrolyte systems. Furthermore, excellent agreement between the theoretical and experimental capacitance was observed for all the tested sp2 carbon materials in these electrolyte systems, indicating that this model can be applied widely in the evaluation of various carbon materials for supercapacitors.

A novel nanohybrid of daunomycin and single-walled carbon nanotubes: photophysical properties and enhanced electrochemical activity

A nanohybrid adduct of the widely used, functional dye, daunomycin (DM), with single-walled carbon nanotubes (SWNTs) was prepared. Ultraviolet-visible-near infrared and fluorescence spectroscopy and electrochemistry of DM-functionalized SWNTs reveal that DM interacts with SWNTs through strong π–π stacking and there is a significant photo-induced charge-transfer interaction between the two components. Importantly, the novel adduct modified the glassy carbon (GC) electrode to give a much enhanced electrochemical activity than those of DM adsorbed onto not only the bare GC electrode but also the SWNTs-modified GC electrode.

Erratum: Single-walled carbon nanotubes-mediated in vivo and in vitro delivery of siRNA into antigen-presenting cells (Gene Therapy (2006) vol. 13 (1714-1723) 10.1038/sj.gt.3302808)

Antigen-presenting cells such as dendritic cells (DCs) play a critical role in inducing and regulating immune responses. One effective strategy for DC-based immunotherapy is to regulate maturation and function of DC. In this study, we apply single-walled carbon nanotubes (SWNTs) to carry small interfering RNA (siRNA) to reach, enter and genetically modify DCs in vivo. We prepared positively charged SWNTs (SWNTs+) using 1,6-diaminohexane which was demonstrated by transmission electron microscopy equipped with energy-dispersive X-ray spectroscopy and atomic force microscope. The functionalized SWNTs+ could absorb siRNA to form complexes of siRNA with SWNTs. These siRNA:SWNT+ complexes were preferentially taken up by splenic CD11c+ DCs, CD11b+ cells and also Gr-1+CD11b+ cells comprising DCs, macrophages and other myeloid cells to silence the targeting gene. Suppressor of cytokine signaling 1 (SOCS1) restricts the ability of DCs to break self-tolerance and induce antitumor immunity. Infusion of SWNTs+ carrying SOCS1siRNA reduced SOCS1 expression and retarded the growth of established B16 tumor in mice, indicating the possibility of in vivo immunotherapeutics using SWNTs-based siRNA transfer system.

Electrodeposited Co–Zn on Ni foam as efficient catalysts for hydrogen generation from hydrolysis of sodium borohydride

For hydrogen generation based on the sodium borohydride hydrolysis, the development and application of efficient catalysts are of key importance. In this work, Co and Co–Zn catalysts were prepared on Ni foam by electrodeposition process. Field-emission scanning electron microscopy (FE-SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) were employed for materials characterization, and catalyst performance was measured by typical water-displacement method. Experimental results indicate that the doping of zinc affects the morphology and microstructure of catalyst and promotes the effective catalytic area, leading to higher hydrogen generation rate (HGR) by comparing with Co/Ni. Furthermore, HGR can be further improved by treating the Co–Zn/Ni with NaOH solution because the partial dissolving of zinc results in the increase of cobalt active sites. Using a 10wt.% NaBH4 and 5wt.% NaOH solution, the HGR was as high as 455mL min−1 g−1 at 25∘C, and the ap...

Monolithic 3D Cross-Linked Polymeric Graphene Materials and the Likes: Preparation and Their Redox Catalytic Applications

While there have been tremendous studies about graphene and its applications in the past decade, so far the proposed huge potential of this material has not been materialized. One of the prerequisites to overcome these challenges is maintaining the nature and intrinsic properties of individual graphene sheets while in the state of bulk material. Thus, in this Perspective contribution, the fabrication/synthesis of the monolithic polymeric and three-dimensional (3D) cross-linked bulk materials (3DGraphene) with (doped) 2D graphene sheets as the building block will first be briefly summarized. Then, the second part will cover the redox catalytic application of these bulk materials including doped 3DGraphene, the graphene-like material polymeric C3N4 and their hybrid materials. These will include mainly oxygen reduction reactions (ORR), hydrogen evolution reactions (HER), and CO2 reduction for their latest development. Finally, challenges and outlook related to the design of 3D cross-linked graphene based materials and their catalytic applications will be briefly discussed.

Data on high performance supercapacitors based on mesoporous activated carbon materials with ultrahigh mesopore volume and effective specific surface area

The data presented in this data article are related to the research article entitled “Mesoporous activated carbon materials with ultrahigh mesopore volume and effective specific surface area for high performance supercapacitors” (Lu et al., 2017) [1]. The detailed structure data of the prepared mesoporous activated carbon materials with ultrahigh mesopore volume and effective specific surface area and the electrochemical performance data of the corresponding supercapacitors are described.