The development of green, controllable and simple pathways for the rapid polymerization of dopamine is of great importance in the applications of polydopamine surface chemistry. Herein, we developed a green strategy to accelerate and control the polymerization of dopamine by using microplasma electrochemistry. It was found that the microplasma cathode could trigger and dramatically accelerate the polymerization process of dopamine. The PDA coating on a silicon wafer could reach a very high deposition rate of about 53 nm h−1, which is comparable to the fastest methods. The on/off mode and the rate of the polymerization reaction could also be regulated easily by the input current. This method could also be applied for creating two-dimensional (2D) surface coating patterns on various substrates.

The removal and separation of uranium from aqueous solutions are quite important for resource reclamation and environmental protection. Being one of the most effective techniques for metal separation, adsorption of uranium by a variety of adsorbent materials has been a subject of study with high interest in recent years. However, current methods for monitoring the adsorption process require complicated procedures and tedious measurements, which hinders the development of processes for efficient separation of uranium. In this work, we prepared a type of luminescent mesoporous silica-carbon dots composite material that has high efficiency for the adsorption of uranium and allows simultaneous in situ monitoring of the adsorption process. Carbon dots (CDs) were prepared in situ and introduced onto amino-functionalized ordered mesoporous silica (SBA-NH2) by a facile microplasma-assisted method. The prepared CDs/SBA-NH2 nanocomposites preserved the high specific surface area of the mesoporous silica, as well as the fluorescent properties of the CDs. Compared with bare SBA-NH2, the CDs/SBA-NH2 nanocomposites showed much improved adsorption ability and excellent selectivity for uranyl ions. Moreover, the fluorescence intensity of the composites decreased along with the increase of uranium uptake, indicating that the CDs/SBA-NH2 nanocomposites could be used for on-site monitoring of the adsorption behavior. More interestingly, the adsorption selectivity of the composites for metal ions was in good agreement with the selective fluorescence response of the original CDs, which means that the adsorption selectivity of CDs-based composite materials can be predicted by evaluating the fluorescence selectivity of the CDs for metal ions. As the first study of CDs-based nanocomposites for the adsorption of actinide elements, this work opens a new avenue for the in situ monitoring of adsorption behavior of CDs-based nanocomposites while extending their application areas.Keywords: adsorption; carbon dots; fluorescence; in situ monitor; uranium;

Plasmon-enhanced fluorescence (PEF) generally requires the samples settled on a metal substrate and the effective enhancement distance is less than 100 nm, which limit its application in intracellular sensing. Herein, we report a nano endoscopy with PEF effect for sensing analytes inside the extremely small volume samples. The nano endoscopy was fabricated by assembling single nanoporous gold nanowire (PGNW) on the tip of a tungsten needle. It was accurately manipulated to insert into a micro droplet, and an effective sensing was realized at micrometre scale with submicrometer resolution. By taking lysozyme as a model sensing target, a 23-fold improvement of sensitivity was obtained, comparing with that of smooth gold nanowire (SGNW). These results indicated that the nano endoscopy can realize a high spatial resolution sensing, showing its potential application in intracellular sensing.

We introduce individual nanoporous Au nanowire (AuNW) as a tunable one-dimensional platform for plasmon-enhanced fluorescence, with an enhancement factor of ∼62, which is ∼8-fold higher than that of smooth AuNWs. Besides, nanoporous AuNWs have much lower background emission than smooth AuNWs. These results indicate that nanoporous AuNWs are an excellent optical sensing platform.

Developing a simple synthesis method and expanding the application of carbon dots have attracted increasing attention. In this report, we have developed a facile method to synthesize fluorescent carbon dots (CDs) with the assistance of atmospheric-pressure microplasma. The CDs could be produced within a few minutes with no need of high temperature, external energy input, and multistep procedures. The as-prepared CDs had a relatively uniform size of approximately 2.3 nm. The FTIR spectrum and the XPS analysis showed that carbonyl groups and amide groups exist on the surface of CDs. The CDs showed bright blue luminescence and high stability in high salt concentration and low pH without further modification. A pH-dependent PL behavior was observed and could be applied for pH sensing in the range of 3–14. Moreover, the CDs could be utilized as a reagent capable of detecting U(VI) with a low detection limit and high selectivity.

•Heavier lanthanides were preferentially extracted by Cyanex 302 at high metal loading.•The stoichiometry of the complex was LnA3·mH2O across the Ln(III) series.•The coordination structures of the lighter and heavier lanthanides were different.•IR and EXAFS data suggested more O and less S were coordinated to heavier lanthanides.•Coordination difference was due to decreasing covalent binding of 4f electrons toward S.The extraction of trivalent lanthanides (LnIII) by purified Cyanex 302 (bis(2,4,4-trimethylpentyl)monothiophosphinic acid, denoted as HA) at high and constant metal loading was studied by the co-extraction of NdIII and other LnIII (where Ln = La to Lu, except Pm), and the results were compared with that of unpurified compound. Heavier lanthanides were extracted preferentially, and the average separation factor of adjacent lanthanides by HA was slightly lower than that by unpurified Cyanex 302. The complexation of LnIII with HA in the organic phase was further investigated by absorption/fluorescence spectroscopic titration, and IR and extended X-ray absorption fine structure spectroscopy. Under the studied experimental conditions, the stoichiometry of the major extracted complex was found to be LnA3·mH2O across the LnIII series, but the coordination structures of the lighter and heavier lanthanides were different. The data suggested that a greater number of sulfur atoms coordinate to lighter lanthanides than to heavier lanthanides.

A series of Pt catalysts supported on activated carbon (AC), carbon molecular sieve (CMS), carbon nanotubes (CNT) and graphite (GR) were prepared by the impregnation method. Their catalytic performances in HI decomposition were evaluated in a fixed bed reactor at temperatures ranging from 400 to 550 °C under atmospheric pressure. The different Pt catalysts before and after HI decomposition at different temperature were characterized by BET, XRD and TEM, respectively. The results of the activity evaluation indicated that the activity order of different Pt catalysts changed significantly with the variation of reaction temperature. At 400 °C, different supported Pt catalysts activities decreased in order of Pt/CMS > Pt/AC > Pt/CNT > Pt/GR. At 450 °C, the activities of different Pt catalysts followed the order of Pt/AC ≈ Pt/CNT > Pt/CMS > Pt/GR. At 500 and 550 °C, the Pt/CNT showed the optimum activity and stability during HI decomposition, which could be attributed to the high dispersion of Pt particles and the special microstructure of CNT. The XRD and TEM results illustrated that the Pt particle size or Pt dispersion in different supported Pt catalysts showed different sensitivity to the reaction temperature.Highlights► AC, CMS, CNT and GR supported Pt catalysts were prepared by impregnation method. ► Their catalytic activities were compared for HI decomposition at 400–550 °C ► Their differences in structure, surface area and morphology were characterized. ► The activity order of various Pt catalysts changed obviously with temperature. ► Pt particle sizes in various catalysts show different sensitivity to temperature.

The first example of well-ordered mesoporous organosilica with high selectivity towards Pb(II) based on host–guest interactions was developed. Due to the high functionalization of a specific macrocyclic host, DCH18C6, with easy accessibility, the mesoporous organosilica showed remarkable recognition and efficient adsorption of Pb(II) in a multicomponent system.

Decomposition of hydrogen iodide (HI) is one of the key reactions in the sulfur–iodine (S–I) thermochemical water splitting promising for the massive hydrogen production. Much effort has been made to explore the preparation of high performance catalyst for this hydrogen-producing reaction. Although platinum has long been found to be an efficient metallic catalyst, it was prone to agglomerate at elevated temperature resulting in a decrease in the hydrogen yield. A series of bimetallic Pt–Ir/C catalysts were prepared by electroless plating to investigate the effect of Ir/Pt molar ratio on the HI conversion compared with Pt/C and Ir/C catalysts. The physical properties and morphology of the catalysts were characterized by BET, XRD, TEM and ICP-AES. The synergistic effect of platinum and iridium with respect to HI decomposition was confirmed by the fact that the bimetallic Pt–Ir/C-0.77 catalyst with 1 wt% Pt loading and 0.77 wt% Ir loading showed much higher catalytic activity and thermostability compared with Pt/C and Ir/C catalyst. Based on the experimental results obtained, it may be concluded that the bimetallic Pt–Ir/C catalyst was supposed to be a cost-effective and high performance catalyst promising to be employed for the hydrogen production via the S–I thermochemical water splitting cycle.

The first example of well-ordered mesoporous organosilica with high selectivity towards Pb(II) based on host–guest interactions was developed. Due to the high functionalization of a specific macrocyclic host, DCH18C6, with easy accessibility, the mesoporous organosilica showed remarkable recognition and efficient adsorption of Pb(II) in a multicomponent system.

We introduce individual nanoporous Au nanowire (AuNW) as a tunable one-dimensional platform for plasmon-enhanced fluorescence, with an enhancement factor of ∼62, which is ∼8-fold higher than that of smooth AuNWs. Besides, nanoporous AuNWs have much lower background emission than smooth AuNWs. These results indicate that nanoporous AuNWs are an excellent optical sensing platform.