Sheet-Isolated MoS2 Used for Dispersing Pt Nanoparticles and its Application in Methanol Fuel Cells.

It is highly challenging to activate the basal plane and minimize the π-π stacking of MoS2 sheets, thus enhancing its catalytic performance. Here, we display an approach for making well-dispersed MoS2 . By using the N-doped multi-walled carbon nanotubes (NMWCNTs) as an isolation unit, the aggregation of MoS2 sheets was effectively reduced, favoring the dispersion of Pt nanoparticles (noted as Pt/NMWCNTs-isolated-MoS2 ). Excellent bifunctional catalytic performance for methanol oxidation and oxygen reduction reaction (MOR/ORR) were demonstrated by the produced Pt/NMWCNTs-isolated-MoS2 . In comparison to Pt nanoparticles supported on MoS2 (Pt/MoS2 ), the MOR activity (2314.14 mA mgpt -1 ) and stability (317.69 mA mgpt -1 after 2 h of operation) on Pt/NMWCNTs-isolatedMoS2 were 24 and 232 times higher, respectively. As for ORR, Pt/NMWCNTs-isolated-MoS2 holds large half-wave potential (0.88 V) and high stability (92.71 % after 22 h of operation). This work presents a tactic for activating the basal planes and reducing the π-π stacking of 2D materials to satisfy their applications in electrocatalysis. In addition, the proposed sheet-isolation method can be used for fabricating other 2D materials to promote the dispersion of nanoparticles, which assist its application in other fields of energy as well as the environment.

Plasmonic Photoelectrochemical Coupling Reactions of para-Aminobenzoic Acid on Nanostructured Gold Electrodes.

Surface plasmon resonance (SPR) bridges photonics and photoelectrochemistry by providing an effective interaction between absorption and confinement of light to surface electrons of plasmonic metal nanostructures (PMNs). SPR enhances the Raman intensity enormously in surface-enhanced Raman spectroscopy (SERS) and leads to the plasmon-mediated chemical reaction on the surface of nanostructured metal electrodes. To observe variations in chemical reactivity and selectivity, we studied the SPR photoelectrochemical reactions of para-aminobenzoic acid (PABA) on nanostructured gold electrodes. The head-to-tail coupling product "4-[(4-imino-2,5-cyclohexadien-1-ylidene)amino]benzoic acid (ICBA)" and the head-to-head coupling product p,p'-azodibenzoate (ADBA) were obtained from PABA adsorbed on PMN-modified gold electrodes. In particular, under acidic and neutral conditions, ICBA was obtained as the main product, and ADBA was obtained as the minor product. At the same time, under basic conditions, ADBA was obtained as the major product, and ICBA was obtained as the minor product. We have also provided sufficient evidence for the oxidation of the tail-to-tail coupling reaction product that occurred in a nonaqueous medium rather than in an aqueous medium. The above finding was validated by the cyclic voltammetry, SERS, and theoretical calculation results of possible reaction intermediates, namely, 4-aminophenlylenediamine, 4-hydroxyphenlylenediamine, and benzidine. The theoretical adsorption model and experimental results indicated that PABA has been adsorbed as para-aminobenzoate on the gold cluster in a bidentate configuration. This work offers a new view toward the modulation of selective surface catalytic coupling reactions on PMN, which benefits the hot carrier transfer efficiency at photoelectrochemical interfaces.

Colorimetric detection of neomycin sulfate in tilapia based on plasmonic core-shell Au@PVP nanoparticles.

The rapid colorimetric detection of neomycin sulfate has been achieved using polyvinyl pyrrolidone shell coated gold nanoparticle (Au@PVP NPs) sol. We also observed that, the aggregation of Au@PVP NPs, possibly caused by the hydrogen bonds formed between neomycin sulfate and PVP shell, generates a new surface plasmon resonance absorption in the wavelength of 600 ~ 700 nm. The proposed method showed an excellent performance towards the determination of neomycin sulfate in wide linear range from 0.01 ~ 10 µM with a correlation coefficient of 0.99 and low detection limit of 1 nM. After extracted with trichloroacetic acid and treated with hot chloroform, neomycin sulfate in the tilapia fish samples was detected with satisfied recovery. Additionally, the high selectivity of Au@PVP NPs sol towards neomycin sulfate has been achieved even in presence of common interfering agents. This method has the advantages of high sensitivity, rapidity, specificity, low cost and no complicated pretreatment procedure.

Copper Nanoparticle and Nitrogen Doped Graphite Oxide Based Biosensor for the Sensitive Determination of Glucose.

Copper nanoparticles with the diameter of 50 ± 20 nm decorated nitrogen doped graphite oxide (NGO) have been prepared through a simple single step carbonization method using copper metal-organic framework (MOF), [Cu2(BDC)2(DABCO)] (where BDC is 1,4-benzenedicarboxylate, and DABCO is 1,4-Diazabicyclo[2.2.2]octane) as precursor. The surface morphology, porosity, surface area and elemental composition of CuNPs/NGO were characterized by various techniques. The as-synthesized CuNPs/NGO nanomaterials were coated on commercially available disposable screen-printed carbon electrode for the sensitive determination of glucose. We find that the modified electrode can detect glucose between 1 μM and 1803 μM (linear range) with good sensitivity (2500 μA mM−1 cm−2). Our glucose sensor also possesses low limits of detection (0.44 μM) towards glucose determination. The highly selective nature of the fabricated electrode was clearly visible from the selectivity studies. The practicability of CuNPs/NGO modified electrode has been validated in the human serum samples. The storage stability along with better repeatability and reproducibility results additionally substantiate the superior electrocatalytic activity of our constructed sensor towards glucose.