Jiantai Ma

Aryne cycloaddition: highly efficient chemical modification of graphene

We have developed a simple and efficient approach for the synthesis of chemically converted graphene sheets via aryne cycloaddition under mild reaction conditions. The resulting highly functionalized and thermally stable aryne-modified graphene sheets can be well dispersed in various solvents.

MOF derived Co3O4 nanoparticles embedded in N-doped mesoporous carbon layer/MWCNT hybrids: extraordinary bi-functional electrocatalysts for OER and ORR

Highly efficient and non-precious metal electrocatalysts for oxygen evolution reactions (OERs) and oxygen reduction reactions (ORRs) are at the heart of key renewable-energy technologies. Nevertheless, developing highly active bi-functional catalysts at low cost for both OER and ORR still remains a huge challenge. In this paper, Co3O4 nanocrystals embedded in N-doped mesoporous graphitic carbon layer/multiwalled carbon nanotube (MWCNT) hybrids are prepared by a facile carbonization and subsequent oxidation process of MWCNT-based metal–organic frameworks (MOFs). As a result, in alkaline media, the hybrid material catalyzes OER with an onset potential of 1.50 V (vs. reversible hydrogen electrode) and an over-potential only of 320 mV to achieve a stable current density of 10 mA cm−2 for at least 25 h. The same hybrids also exhibit similar catalytic activity but superior stability to the commercial 20 wt% Pt/C catalyst for ORR, making it a high-performance cheap bi-catalyst for both OER and ORR. The design concept of nonmetal-doped and precious-metal-free electrocatalysts from MOFs can be extended to fabricate other novel, stable and easy to use catalyst systems for advanced applications.

Pd immobilized on amine-functionalized magnetite nanoparticles: a novel and highly active catalyst for hydrogenation and Heck reactions

A palladium-based catalyst supported on amine-functionalized magnetite nanoparticles was successfully prepared by a facile one-pot template-free method combined with a metal adsorption–reduction procedure. The catalyst was characterized by TEM, XRD, XPS, FT-IR and VSM. The catalyst afforded fast conversions for various aromatic nitro and unsaturated compounds, and with a turn-over frequency (TOF) of 83.33 h−1 under a H2 atmosphere in ethanol, even at room temperature. Furthermore, it was found that the catalyst showed a high activity for the Heck reaction, affording over a 93% yield in all the cases investigated. Interestingly, the novel catalyst could be recovered in a facile manner from the reaction mixture and recycled eight times without any significant loss in activity.

Metal organic framework derived magnetic porous carbon composite supported gold and palladium nanoparticles as highly efficient and recyclable catalysts for reduction of 4-nitrophenol and hydrodechlorination of 4-chlorophenol

The development of low cost noble metal nanocatalysts with high activity and selectivity, high catalytic performance, convenient separation, and reusability is a significant challenge. Herein, the magnetic porous carbon (MPC) composite synthesized from metal organic framework (MOF) was used as a catalyst support to fabricate gold (Au) and palladium (Pd) nanoparticle (NP) based nanocatalysts. The MPC not only provided a large surface area and mesopores on which the active centers (Au and Pd NPs) were finely dispersed, but also exhibited superparamagnetic behaviour that enabled the magnetic separation and convenient recovery of the nanocatalysts from the reaction mixture. Thus, the nanocatalysts were repeatedly used without loss of catalytic efficiency. Both the Au/MPC and Pd/MPC nanocatalysts showed excellent catalytic activity for the reduction of 4-nitrophenol. Moreover, the Pd/MPC nanocatalyst exhibited higher efficiency toward hydrodechlorination of 4-chlorophenol compared to the other reported catalysts. This study indicated that the noble metal NPs (NMNPs) supported on MOF-derived MPC materials could act as promising catalysts exhibiting potential applications in numerous NMNP based catalytic reactions.

Palladium nanoparticles immobilized on core–shell magnetic fibers as a highly efficient and recyclable heterogeneous catalyst for the reduction of 4-nitrophenol and Suzuki coupling reactions

In this study, a novel core–shell magnetic fibrous nanocatalyst, Pd/Fe3O4@SiO2@KCC-1 with easily accessible active sites and a convenient recovery by applying an external magnetic field, was successfully developed. Fe3O4@SiO2@KCC-1 was functionalized with amino groups which act as robust anchors so that the palladium nanoparticles (Pd NPs) with an average diameter of about 4 nm were well-dispersed on the fibers of Fe3O4@SiO2@KCC-1 without obvious aggregation. The synthesized Pd/Fe3O4@SiO2@KCC-1 nanocatalyst exhibited excellent catalytic activity in the reduction of 4-nitrophenol by sodium borohydride, and the Suzuki cross coupling reactions of aryl chlorides with aryl boronic acids due to the easy accessibility of the active sites. Furthermore, the Pd/Fe3O4@SiO2@KCC-1 nanocatalyst was conveniently recovered by a magnet and could be reused for at least five cycles without significant loss in activity, thus confirming its good stability. Therefore, the abovementioned approach based on core–shell magnetic fibrous Fe3O4@SiO2@KCC-1 provided a useful platform for the fabrication of Pd NPs based catalysts with easy accessibility, superior activity and convenient recovery.

Rhodamine group modified SBA-15 fluorescent sensor for highly selective detection of Hg2+ and its application as an INHIBIT logic device

Rhodamine group modified SBA-15 nanocomposite (R3-SBA-15) is investigated as a highly selective Hg2+ sensor. The colorless sensor converts to red color in the presence of Hg2+ with the fluorescent detection limit for Hg2+ in MeCN–H2O solution (9 : 1 v/v) being 15 ppb levels and exhibits excellent Hg2+-specific luminescence enhancement over various competitive cations, including alkali and earth, the first-row transition metals and heavy metals. According to the definition of Boolean Logic, using Hg2+ and S2− as inputs, the fluorescence intensity signal changes of R3-SBA-15 as outputs, R3-SBA-15 can act as an INHIBIT logic gate. All the results suggest that R3-SBA-15 was possible for real-time quantitative detection of Hg2+ and the convenience for potential application as a logic gate operated at the nanoscale level.

A facile preparation of CoFe2O4 nanoparticles on polyaniline-functionalised carbon nanotubes as enhanced catalysts for the oxygen evolution reaction

Designing and preparing highly efficient non-precious metal electrocatalysts for the oxygen evolution reaction (OER) is extremely urgent but still remains a challenge. In this study, a polyaniline–multiwalled carbon nanotube (PANI-MWCNT) supported, high performance CoFe2O4 nanoparticle (NP) loaded electrocatalyst (CoFe2O4/PANI-MWCNTs) is synthesized through a novel and simple in situ process under mild conditions. It is found that the introduction of PANI improves the synergistic effect between the CoFe2O4 NPs and MWCNTs, so as to promote the electrical conductivity and stability of the catalyst. Meanwhile, PANI provides more active sites to attach CoFe2O4 NPs uniformly and tightly. Electrochemical measurement shows that the electrocatalyst displays excellent OER activities at a low overpotential of 314 mV for 10 mA cm−2 current density and a small Tafel slope of 30.69 mV dec−1 in 1 M KOH at a scan rate of 5 mV s−1. Furthermore, this electrocatalyst exhibits remarkably good durability evaluated by continuously cycling for 1000 cycles and stably working at 0.54 V (vs. Ag/AgCl) for at least 40 h. The achieved results confirm that the CoFe2O4/PANI-MWCNT hybrid is an earth-abundant and cheaply fabricated anode material for OER.

Imidazolium ionic liquid-modified fibrous silica microspheres loaded with gold nanoparticles and their enhanced catalytic activity and reusability for the reduction of 4-nitrophenol

A new type of catalyst based on the ionic liquid (IL) modified fibrous nano-silica material KCC-1, with a high surface area, as the support and Au nanoparticles (NPs) as the active sites (KCC-1–IL/Au), has been successfully prepared through a facile and environmentally-friendly approach and characterized by Fourier transform infrared (FT-IR) spectroscopy, X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM), thermal gravimetric analysis (TGA), elemental analysis and inductively coupled plasma atomic emission spectroscopy (ICP-AES). The synthesized catalyst exhibited high catalytic activity in the reduction of 4-nitrophenol by NaBH4 due to not only the unique dendritic fibrous morphology of the support, which made the active sites accessible, but also the synergistic effect between KCC-1–IL and the small Au NPs. Additionally, KCC-1–IL/Au had good recyclability, mainly attributed to the IL groups, which acted as robust anchors to avoid Au NP leaching from the support. This synthetic method provides a green way to effectively prepare low-cost Au-based catalysts and is promising for the development of other useful materials.

Magnetic Fe nanoparticle functionalized water-soluble multi-walled carbon nanotubules towards the preparation of sorbent for aromatic compounds removal

Magnetic Fe nanoparticle functionalized water-soluble multi-walled carbon nanotubules (MWNTs) were prepared, characterized and used for the removal of aromatic compounds in water and re-use.

Enhancing catalytic performance of Au catalysts by noncovalent functionalized graphene using functional ionic liquids

New catalyst, prepared through Au nanoparticles anchored on the Ionic Liquid of 3,4,9,10-perylene tetracarboxylic acid-noncovalent functionalized graphene (Au/PDIL-GS), was fabricated using a facile and environment-friendly approach. The information of the morphologies, sizes, dispersion of Au nanoparticles (NPs) and chemical composition for the as-prepared catalysts was verified by systematic characterizations, including transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Raman spectra, X-ray diffraction (XRD) and X-Ray photoelectron spectroscopy (XPS). As a new catalyst, the resulting Au/PDIL-GS exhibited excellent catalytic activity in the reduction of 4-nitrophenol because of the synergistic effect between the PDIL-GS and Au NPs. The facile and environment-friendly approach provides a green way to effectively synthesize low cost Au-based catalysts for 4-NP reduction and is promising for the development of other useful materials.