Mn-doped CoSe2 nanosheets as high-efficiency catalysts for the oxygen evolution reaction.

In this work, we introduce for the first time an aqueous solution method followed by a selenization step to prepare Mn-doped CoSe2 nanosheets supported on nickel foam for the oxygen evolution reaction. These findings provide us highly efficient electrocatalysts instead of noble metal catalysts for the oxygen evolution reaction.

Highly Dispersed Metal Carbide on ZIF-Derived Pyridinic-N-Doped Carbon for CO2 Enrichment and Selective Hydrogenation.

Catalytic conversion of CO2 into chemicals is a critical issue for energy and environmental research. Among such reactions, converting CO2 into CO has been regarded as a significant foundation to generate a liquid fuels and chemicals on a large scale. In this work, zeolitic imidazolate framework-derived N-doped carbon-supported metal carbide catalysts (M/ZIF-8-C; M=Ni, Fe, Co and Cu) with highly dispersed metal carbide were prepared for selective CO2 hydrogenation. Under the same metal loadings, catalytic activity for CO2 hydrogenation to CO follows the order: Ni/ZIF-8-C≈Fe/ZIF-8-C>Co/ZIF-8-C>Cu/ZIF-8-C. These catalysts are composed of carbide or metal supported on pyridinic N sites within the N-doped carbon structure. ZIF-8-derived pyridinic nitrogen and carbide effect CO2 adsorption, whereas dispersed Ni or Fe carbide and metal species serve as an active site for CO2 hydrogenation. The supported Ni catalyst exhibits extraordinary catalytic performance, which results from high dispersion of the metal and exposure of the carbide. Based on high-sensitivity low-energy ion scattering (HS-LEIS) and line scan results, density functional theory (DFT) was used to understand reaction mechanism of selective CO2 hydrogenation over Ni/ZIF-8-C. The product CO is derived mainly from the direct cleavage of C-O bonds in CO2 * rather than decomposition of COOH*. The CO* desorption energy on Ni/ZIF-8-C is lower than that for further hydrogenation and dissociation. Comparison of Ni/ZIF-8-C with ZIF-8-C indicates that the combined effects of the highly dispersed metal or carbide and weak CO adsorption result in high CO selectivity for CO2 hydrogenation.

Quantum dot-Eu3+ conjugate as a luminescence turn-on sensor for ultrasensitive detection of nucleoside triphosphates.

We report a conjugate of thioglycolic acid (TGA) capped CdTe quantum dot and Eu(3+) ion (TGA-CdTe QD-Eu(3+)) that can be used as an ultrasensitive luminescence turn-on sensor for nucleoside triphosphates (NTPs). The TGA-CdTe QD-Eu(3+) conjugate is a weakly luminescent species as a result of the strong quenching effect of Eu(3+) ion on the luminescence of TGA-CdTe QDs. The conjugate's luminescence can be readily restored by its reaction with adenosine triphosphate (ATP) and other NTPs, and thus gives an ultrasensitive detection of NTPs, with a detection limit of 2 nM. The sensing mechanism has also been explored, and the effective quenching of TGA-CdTe QDs emission by Eu(3+) ions has been attributed to photoinduced electron transfer (PET). ATP, as the representative of NTPs, can remove Eu(3+) from the surface of TGA-CdTe QDs, leading to restoration of the TGA-CdTe QDs luminescence.

Ultrasensitive detection of phenolic compounds based on a spin-labeled luminescent lanthanide complex.

Herein we propose a novel method for ultrasensitive detection of phenolic compounds. This method was developed based on a spin-labeled terbium complex Tb(3+)/cs124-DTPA-TEMPO (1). This spin-labeled terbium complex is a weakly luminescent compound and shows strong off-on luminescent response to phenolic compounds in the presence of horseradish peroxidase (HRP), glutathione (GSH) and hydrogen peroxide. The analyte recognition and signaling mechanism are discussed and the factors affecting the off-on luminescence have been explored. Detection limits of 1.1 nM for phenol, 1.1 nM for resorcine, 0.6 nM for m-cresol, 3 nM for p-cresol, and 0.5 nM for 2,4-dichlorophenol were obtained, respectively. The practicability of the proposed method has been tested in detection of the concentration of spiked nearshore seawaters, and recoveries of 77.4-80.4% with relative standard deviations (RSDs) of 1.0-2.2% were obtained.

A highly sensitive and selective antioxidant probe based on a bi-modally functionalized conjugated polyelectrolyte.

A new water-soluble anionic conjugated polyelectrolyte with a nitroxide radical covalently linked to the sulfonated poly(phenylene ethynylene) backbone (PPE-SO(3)) is reported. This radical-functionalized PPE-SO(3) (RF-PPE-SO(3)) demonstrates fluorescence and electron spin resonance (ESR) bimodal signaling function and shows sensitive and selective response to antioxidants.

A long-lived luminescence and EPR bimodal lanthanide-based probe for free radicals.

We developed a novel spin-labeled terbium complex Tb(3+)/cs124-DTPA-TEMPO (1) by covalently labeling a nitroxide radical on the terbium complex for monitoring free radicals of various areas. This lanthanide complex probe shows a high EPR signal which resulted from the nitroxide radical moiety, and is weakly luminescent which resulted from the intramolecular quenching effect of the nitroxide radical on sensitised terbium luminescence. The intensity of both the EPR and luminescence can be modulated by eliminating the paramagnetism of the nitroxide radical through recognition of a carbon-centered radical analyte and thus gives a quantification of the analyte. We have preliminarily applied this probe in the luminescent detection of model carbon-centered radicals and hydroxyl radicals (·OH). This probe is water-soluble and contains lanthanide-luminescence properties, favorable for the time-resolved luminescence technique. The investigation of the intramolecular quenching process has showed that the labeled nitroxide radical quenches multiple excited states of the terbium complex, resulting in highly efficient quenching of terbium luminescence. This probe is the first example of intramolecular modulation of lanthanide luminescence by a nitroxide radical.

Metal and metalloid contaminant availability in Yundang Lagoon sediments, Xiamen Bay, China, after 20 years continuous rehabilitation.

This study is focused on the pollutant level of sediments after 20 years continuous rehabilitation in Yundang Lagoon, Xiamen Bay, one of the most developed harbors in China. The modified BCR fractionation scheme was employed in sediments for the partition of particulating metals and metalloids. Moreover, the potential environment risks of these pollutants were evaluated by using Håkanson indexes. The results showed that the sediments were slightly contaminated by Cu, Pb, Zn, Cr, Ni, Mn, Ag, As and Se. A major portion (30-46%) of Mn was strongly associated with the acid soluble fraction. Copper (Cu), Cr and Ni exhibit significant oxidisable fraction (from 22 to 32%), Pb, Cr, As, Zn, Se and Ag showed considerable concentration (>50%) in the residual phase. Environment risk evaluation showed that the pollution in Yundang Lagoon is moderate and the ranking of the contaminants followed the order: As>Ni>Pb>Cu>Cr>Zn. Importantly, though these results indicate that the concentrations of heavy metals in sediments here are also higher than the sediment quality guidelines and may pose a potential threat to these areas and so the efforts in remediation should be continued.

Fluorescent core-shell silica nanoparticles as tunable precursors: towards encoding and multifunctional nano-probes.

Core-shell silica nanoparticles comprised of a RuBpy doped silica core and a Pas-DTPA doped silica shell were synthesized and post-functionalized with an encoding fluorescence combination and multiplex imaging function.