Xiangjie Bo

Fabrication of 2D ordered mesoporous carbon nitride and its use as electrochemical sensing platform for H2O2, nitrobenzene, and NADH detection.

Two-dimensional ordered mesoporous carbon nitride (OMCN) has been successfully prepared for the first time using SBA-15 mesoporous silica and melamine as template and precursor respectively, by a nano hard-templating approach. A series of OMCN-x samples with different pyrolysis temperatures have been reported. The formation of these composite materials was verified by detailed characterization (e.g., Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, N2 adsorption, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy). The results showed that the materials were structurally well ordered with two-dimensional porous structure, high surface area and large pore volume. The influence of BET surface area and different amounts of N-bonding configurations formed at different pyrolysis temperatures of OMCN-x for the electrocatalysis towards hydrogen peroxide, nitrobenzene, and nicotinamide adenine dinucleotide were investigated in detail. Results indicated that OMCN treated at 800°C with largest BET surface area and highest amounts of pyrindinic N showed improved electrocatalytic activity for H2O2, nitrobenzene, and NADH in neutral solution.

In situ growth of copper sulfide nanoparticles on ordered mesoporous carbon and their application as nonenzymatic amperometric sensor of hydrogen peroxide

A simple and facile synthetic method to incorporate copper sulfide (Cu(2)S) nanoparticles inside the mesopores of ordered mesoporous carbons (OMCs) is reported. The Cu(2)S/OMCs nanocomposite was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption-desorption. The results show that the incorporation of Cu(2)S nanoparticles inside the pores of OMCs does not change the highly ordered two-dimensional hexagonal mesostructure of OMCs matrix. Nonenzymatic amperometric sensor of hydrogen peroxide based on the Cu(2)S/OMCs nanocomposite modified glassy carbon (GC) electrode is developed. Compared with the pristine OMCs modified electrode, the Cu(2)S/OMCs modified electrode displays high electrocatalytic activity towards hydrogen peroxide and gives linear range from 1 to 3030 microM (R=0.9986). The sensor also exhibits good ability of anti-interference to electroactive molecules. The combination of the unique properties of Cu(2)S nanoparticles and the ordered mesostructure of OMCs matrix guarantee the excellent electrocatalysis for hydrogen peroxide. The good analytical performance and low-cost make Cu(2)S/OMC nanocomposite promising for the development of effective sensor for hydrogen peroxide.

Nonenzymatic amperometric sensor of hydrogen peroxide and glucose based on Pt nanoparticles/ordered mesoporous carbon nanocomposite

A simple and facile synthetic method to incorporate Pt nanoparticles inside the mesopores of ordered mesoporous carbons (OMCs) is reported. The Pt/OMCs nanocomposite was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and nitrogen adsorption-desorption. The results show that the incorporation of Pt nanoparticles inside the pores of OMCs does not change the highly ordered two-dimensional hexagonal mesostructure of OMCs matrix. Nonenzymatic amperometric sensor of hydrogen peroxide and glucose based on the Pt/OMCs nanocomposite-modified glassy carbon (GC) electrode is developed. Compared with the original OMCs-modified electrode, the Pt/OMCs-modified electrode displays improved current response towards hydrogen peroxide and gives linear range from 2 to 4212 microM. At an applied potential of -0.08 V, the Pt/OMCs nanocomposite gives linearity in the range of 0.5-4.5 mM glucose in neutral buffered saline solution. This glucose sensor also exhibits good ability of anti-interference to electroactive molecules. The combination the unique properties of Pt nanoparticles and the ordered mesostructure of OMCs matrix guarantees the enhanced response for hydrogen peroxide and glucose.

Highly exposed Pt nanoparticles supported on porous graphene for electrochemical detection of hydrogen peroxide in living cells

In this study, we developed a novel biosensor based on highly exposed Pt nanoparticles (Pt NPs) decorated porous graphene (PG) for the reliable detection of extracellular hydrogen peroxide (H2O2) released from living cells. The commercially available low-cost hydrophilic CaCO3 spheres were used as template for preparing PG. The porous structure provided larger surface area and more active sites. Due to the porous structure of PG, the Pt NPs supported on PG were not secluded by aggregated graphene layers and were highly exposed to target molecules. Ultrafine Pt NPs were well dispersed and loaded on PG by a method of microwave assistance. Electrochemical performances of the Pt/PG nanocomposites modified glassy carbon electrode (GCE) were investigated. The electrocatalytic reduction of H2O2 showed a wide linear range from 1 to 1477 μM, with a high sensitivity of 341.14 μA mM(-1) cm(-2) and a limit of detection (LOD) as low as 0.50 μM. Moreover, the Pt/PG/GCE exhibited excellent anti-interference property, reproducibility and long-term storage stability. Because of these remarkable analytical advantages, the constructed sensor was used to determine H2O2 released from living cells with satisfactory results. The superior catalytic activity makes Pt/PG nanocomposites a promising candidate for electrochemical sensors and biosensors design.

Cobalt and nitrogen co-embedded onion-like mesoporous carbon vesicles as efficient catalysts for oxygen reduction reaction

A series of cobalt and nitrogen co-embedded onion-like mesoporous carbon vesicles (Co–NMCVs) were synthesized as non-noble metal catalysts for the first time. Physical characterization indicated that the Co–NMCVs samples all retain the lamellar porous shell structure (accompanying considerable surface areas and pore volumes), except the Co20–NMCV sample. Electrochemical measurements demonstrate that most of the Co–NMCV catalysts exhibit remarkable oxygen reduction reaction (ORR) activity in both acidic and alkaline media. Particularly, the Co10–NMCV catalyst exhibits a more positive onset voltage of −0.13 V (only 50 mV deviation from Pt/C), a higher half-wave potential of −0.18 V (only 20 mV deviation from Pt/C), and better selectivity (electron-transfer number >3.92) for the ORR in alkaline medium. Meanwhile, the Co10–NMCV catalyst also shows higher durability of the ORR catalytic activity and better methanol tolerance than the commercial Pt/C catalyst. The unprecedented performance of the Co10–NMCV catalyst in ORR is attributed to the homogeneous distribution of abundant Co–N active sites (having the dominant effect for the ORR catalytic activity) on the surface of the MCV matrix (which has the onion-like lamellar structure, high specific surface area, and large pore volume), which observably enhance the active site density of the Co10–NMCV catalyst. All experimental results demonstrate that the Co10–NMCV catalyst may be exploited as the potentially efficient and inexpensive non-noble metal ORR catalyst to replace Pt-based catalysts.

Facile synthesis of ultrafine Co3O4 nanocrystals embedded carbon matrices with specific skeletal structures as efficient non-enzymatic glucose sensors

A facile, effective, and environmentally friendly method has been adopted for the first time to prepare tiny Co3O4 nanocrystals embedded carbon matrices without using surfactants, harmful organic reagents or extreme conditions. Structural characterizations reveal that the size-controlled Co3O4 nanocrystals are uniformly dispersed on carbon matrices. Electrochemical measurements reveal that Co3O4-ordered mesoporous carbon (OMC) can more efficiently catalyze glucose oxidation and acquire better detection parameters compared with those for the Co3O4-macroporous carbon, Co3O4-reduced graphene oxide, and free Co3O4 nanoparticles (NPs) (such as: the large sensitivity (2597.5 μA cm(-2) mM(-1) between 0 and 0.8 mM and 955.9 μA cm(-2) mM(-1) between 0.9 and 7.0 mM), fast response time, wide linear range, good stability, and surpassingly selective capability to electroactive molecules or Cl(-)). Such excellent performances are attributed to the synergistic effect of the following three factors: (1) the high catalytic sites provided by the uniformly dispersed and size-controlled Co3O4 nanocrystals embedded on OMC; (2) the excellent reactant transport efficiency caused by the abundant mesoporous structures of OMC matrix: (3) the improved electron transport in high electron transfer rate (confinement of the Co3O4 NPs in nanoscale spaces ensured intimate contact between Co3O4 nanocrystals and the conducting OMC matrix). The superior catalytic activity and selectivity make Co3O4-OMC very promising for application in direct detection of glucose.

Facile synthesis of various highly dispersive CoP nanocrystal embedded carbon matrices as efficient electrocatalysts for the hydrogen evolution reaction

In order to promote the hydrogen evolution reaction (HER) catalytic efficiency of cobalt phosphide (CoP) and then construct efficient HER catalysts, a facile procedure has been adopted to prepare tiny CoP nanoparticle (NP) embedded carbon matrices without using any extreme conditions and harmful organic reagents or surfactants. Meanwhile, in order to explore the influence of structures of carbon matrices on preventing the free growth of CoP NPs and enhancing the HER catalytic efficiency of the CoP–carbon catalysts, imporous reduced graphene oxide (RGO), macroporous carbon (MPC), mesoporous carbon vesicles (MCVs) and ordered mesoporous carbon (OMC) were used for preparing CoP–carbon HER catalysts. SEM and TEM measurements show that size-controlled CoP NPs indeed grew more uniformly on the OMC frameworks than those on MCVs, MPC and RGO. As expected, the HER is catalyzed more efficiently on CoP–OMC accompanied by a small onset potential of −77.74 mV vs. RHE, a low Tafel slope of 56.67 mV dec−1, a small over-potential value of 112.18 mV at 10 mA cm−2, and the outstanding long-term stability. These results show that CoP–OMC inherently exhibits better HER catalytic activity than other CoP-based catalysts in acidic electrolytes. Such excellent performances are attributed to the synergistic effect of the highly catalytic sites provided by the uniformly dispersed and size-controlled CoP NPs embedded on OMC, excellent proton transport efficiency, and improved electron transport with a high electron transfer rate. Our results provide useful information that the mesoporous conductive matrices could be applied to greatly improve the HER catalytic efficiency of various HER catalytically active centers.

One-pot ionic liquid-assisted synthesis of highly dispersed PtPd nanoparticles/reduced graphene oxide composites for nonenzymatic glucose detection.

A series of highly dispersed bimetallic PtPd alloy nanoparticles (NPs) anchored on reduced graphene oxide (RGO) have been synthesized with the assistance of ionic liquid (IL: [VEIM]BF4). Different ratios of (PtCl6)(2-) and (PdCl4)(2-) ions were firstly attached to IL functionalized graphene oxide (GO) sheets in ethylene glycol (EG), and then the encased metal ions and graphene oxide sheets were reduced simultaneously by EG with the assistance of microwave. The characterization results of scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and X-ray diffraction (XRD) demonstrate that PtPd alloy NPs with small particle sizes are uniformly dispersed on RGO. Electrochemical measurements reveal that PtPd-IL-RGO modified electrode can directly catalyze glucose oxidation and display enhanced current response compared with PtPd-RGO (such as: a response time within 3s, a linear range from 0.1 to 22 mM at 0 V, good reproducibility, considerable stability, and excellent anti-interference to electroactive molecules and Cl(-)). The superior catalytic activity and selectivity make PtPd-IL-RGO nanomaterials very promising for applications in direct detection of glucose.

A sensitive amperometric sensor for hydrazine and hydrogen peroxide based on palladium nanoparticles/onion-like mesoporous carbon vesicle

Onion-like mesoporous carbon vesicle (MCV) with multilayer lamellar structure was synthesized by a simply aqueous emulsion co-assembly approach. Palladium (Pd) nanoparticles were deposited on the MCV matrix (Pd/MCV) by chemical reduction of H(2)PdCl(4) with NaBH(4) in aqueous media. Pd(X)/MCV (X wt.% indicates the Pd loading amount) nanocomposites with different Pd loading amount were obtained by adjusting the ratio of precursors. The particular structure of the MCV results in efficient mass transport and the onion-like layers of MCV allows for the obtainment of highly dispersed Pd nanoparticles. The introduction of Pd nanoparticles on the MCV matrix facilitates hydrazine oxidation at more negative potential and delivers higher oxidation current in comparison with MCV. A linear range from 2.0 x 10(-8) to 7.1 x 10(-5) M and a low detection limit of 14.9 nM for hydrazine are obtained at Pd(25)/MCV nanocomposite modified glassy carbon (GC) electrode. A nonenzymatic amperometric sensor for hydrogen peroxide based on the Pd(25)/MCV nanocomposite modified GC electrode is also developed. Compared with MCV modified GC electrode, the Pd(25)/MCV nanocomposite modified GC electrode displays enhanced amperometric responses towards hydrogen peroxide and gives a linear range from 1.0 x 10(-7) to 6.1 x 10(-3) M. The Pd(25)/MCV nanocomposite modified GC electrode achieves 95% of the steady-current for hydrogen peroxide within 1s. The combination of the unique properties of Pd nanoparticles and the porous mesostructure of MCV matrix guarantees the improved analytical performance for hydrazine and hydrogen peroxide.

Ultra-fine Pt nanoparticles supported on ionic liquid polymer-functionalized ordered mesoporous carbons for nonenzymatic hydrogen peroxide detection.

Poly(ionic liquid) (PIL) coated ordered mesoporous carbons (OMCs) were prepared by in situ polymerization of 3-ethyl-1-vinylimidazolium tetrafluoroborate ([VEIM]BF(4)) monomer on OMCs matrix. PIL on the surface of OMCs can provide sufficient binding sites to anchor the precursors of metal ion. PIL/OMCs were employed as support material for the deposition and formation of ultra-fine Pt nanoparticles, via the self-assembly between the negative Pt precursor and positively charged functional groups of PIL-functionalized OMCs. The combination of the unique properties of each component endows Pt/PIL/OMCs as a good electrode material. Compared with the Pt/OMCs nanocomposite, the Pt/PIL/OMCs modified electrode displays high electrocatalytic activity towards hydrogen peroxide (H(2)O(2)) and gives linear range from 1.0 × 10(-7) to 3.2 × 10(-3) M (R=0.999). The Pt/PIL/OMCs responds very rapidly to the changes in the level of H(2)O(2), producing steady-state signals within 4-5s. A high sensitivity of 24.43 μA mM(-1) and low detection limit of 0.08 μM was obtained at Pt/PIL/OMCs modified electrode towards the reduction of H(2)O(2). The improved activity makes Pt/PIL/OMCs nanocomposite promising for being developed as an attractive robust and new electrode material for electrochemical sensors and biosensors design.