Copper(II)-Doped Two-Dimensional Titanium-Based Metal-Organic Frameworks toward Light-Driven CO2 Reduction to Value-Added Products.

Recently, metal-organic framework (MOF)-based photocatalysts for an efficient CO2 reduction reaction have drawn wide attention in multidisciplinary fields and sustainable chemistry. In this work, a series of Cu2+-doped two-dimensional Ti-based MOFs were fabricated by a facile in situ solvothermal method. Cu2+ ions were doped in equal proportions and uniformly dispersed in the crystal structure of the MOF matrix. Interestingly, the doping content of Cu2+ ions and the photocatalytic performance displayed an obvious volcanic relationship, the medium-concentration Cu2+-doped sample (T1-2Cu) held the greatest activity with 100% carbonaceous product (CH4 and CO) formation, and the CH4 production rate was 3.7 µmol g-1 h-1 with 93% electron selectivity. The band structure, local electronic structure, carrier separation kinetics, and CO2 adsorption studies demonstrated that the excellent photocatalytic activity of T1-2Cu benefited from the appropriate amount of Cu2+ ion doping: (1) a doping amount of 2 atom % optimized the conduction band position of the MOF substrate and endowed T1-2Cu with strong reduction potential in thermodynamics, (2) doping Cu2+ ions tuned the local electronic environment around titanium oxide clusters and optimized the generation, separation, and migration processes of photoinduced carriers, and (3) the introduction of Cu2+ ions also provided more accessible active sites and more probabilities for the adsorption and activation of CO2 reactants.

Tunable Electronic Metal-Support Interactions on Ceria-Supported Noble-Metal Nanocatalysts in Controlling the Low-Temperature CO Oxidation Activity.

A fundamental study on the metal-support interactions of supported metal catalysts is of great importance for developing heterogeneous catalysts with high performance, is still attracting and challenging in many heterogeneous catalytic reactions. In this work, we report the catalytic performances of CeO2-supported noble-metal catalysts among single atoms, subnanoclusters (∼1 nm), and nanoparticles (2.2-2.7 nm) upon low-temperature CO oxidation reaction between 50 and 250 °C. The subnanoclusters and nanoparticles of Ru, Rh, and Ir showed much higher activities than those of the single atoms, while a Pd single-atom catalyst was more active than Pd subnanoclusters and nanoparticles. According to the results of multiple ex situ and in situ characterizations, the much different activities of Ru, Rh, Ir, and Pd were derived from the alterable electronic metal-support interactions (EMSI), which determine the concurrent reaction pathway including the famous Mars van Krevelen mechanism and carbonate-intermediate route on the most active metal sites of Mδ+ (0 < δ < 1) for Ru, Rh, and Ir and Pd2+ for Pd. Also, the moderate EMSI of CeO2-supported Rh subnanoclusters furthest benefited activation of the adsorbed CO molecule and ensured it the highest activity among CeO2-supported Ru, Rh, and Ir catalysts with similar metal deposit sizes.

Exposure of low-concentration arsenic-initiated inflammation and autophagy in rat lungs.

Chronic arsenic exposure through water intake is a worldwide issue, which has caused many diseases. Lungs are the first target organ of arsenic and lung inflammation, autophagy, and even the onset of tumors can be induced by arsenic exposure. Here, we tested the outcome of low-concentration arsenic exposure in rat lungs. Tissue changes, inflammation, autophagy, and other physiological responses were observed in this study. Results showed that low-concentration exposure of arsenite through water intake could initiate autophagy and inflammation in lungs but high concentration exposure produced a weak autophagy response and accentuated inflammation with the possibility of a chronic inflammation environment emerging followed by tumorigenesis.

Two-photon fluorescent probes for biological Mg(2+) detection based on 7-substituted coumarin.

Two novel water-soluble coumarin-based compounds (OC7, NC7) were designed and synthesized as two-photon fluorescent probes for biological Mg(2+) detection. The compounds feature a ß-keto acid as a high selective binding site for Mg(2+) and the coumarin framework as the two-photon fluorophore. OC7 and NC7 show significant "off-on" detecting signals (9.05-fold and 23.8-fold fluorescence enhancement) and lower detection limits compared with previous reported two-photon fluorescent probes for Mg(2+). Moreover, OC7-Mg(2+) and NC7-Mg(2+) exhibit large two-photon absorption cross sections (340 and 615 GM) at the near-infrared wavelengths (740 and 860 nm), which indicates that the probes are very suitable for detection of Mg(2+) in vivo. Both OC7 and NC7 are pH-insensitive and of low cytotoxicity and can be applied to image intracellular Mg(2+) under two-photon microscopy (TPM). Our results provide a strategy to modify the coumarin fluorophore to get better two-photon fluorescent properties. And the results also suggest that electronic density of ß-keto acid plays a very important role in the recognition of Mg(2+).

Probing the atomically diffuse interfaces in Pd@Pt core-shell nanoparticles in three dimensions.

Deciphering the three-dimensional atomic structure of solid-solid interfaces in core-shell nanomaterials is the key to understand their catalytical, optical and electronic properties. Here, we probe the three-dimensional atomic structures of palladium-platinum core-shell nanoparticles at the single-atom level using atomic resolution electron tomography. We quantify the rich structural variety of core-shell nanoparticles with heteroepitaxy in 3D at atomic resolution. Instead of forming an atomically-sharp boundary, the core-shell interface is found to be atomically diffuse with an average thickness of 4.2 Å, irrespective of the particle's morphology or crystallographic texture. The high concentration of Pd in the diffusive interface is highly related to the free Pd atoms dissolved from the Pd seeds, which is confirmed by atomic images of Pd and Pt single atoms and sub-nanometer clusters using cryogenic electron microscopy. These results advance our understanding of core-shell structures at the fundamental level, providing potential strategies into precise nanomaterial manipulation and chemical property regulation.

The site pair matching of a tandem Au/CuO-CuO nanocatalyst for promoting the selective electrolysis of CO2 to C2 products.

Tandem catalysis, in which a CO2-to-C2 process is divided into a CO2-to-CO/*CO step and a CO/*CO-to-C2 step, is promising for enhancing the C2 product selectivity when using Cu-based electrochemical CO2 reduction catalysts. In this work, a nanoporous hollow Au/CuO-CuO tandem catalyst was used for catalyzing the eCO2RR, which exhibited a C2 product FE of 52.8% at -1.0 V vs. RHE and a C2 product partial current density of 78.77 mA cm-2 at -1.5 V vs. RHE. In addition, the C2 product FE stably remained at over 40% over a wide potential range, from -1.0 V to -1.5 V. This superior performance was attributed to good matching in terms of the optimal working potential and charge-transfer resistance between CO/*CO-production sites (Au/CuO) and CO/*CO-reduction sites (CuO). This site pair matching effect ensured sufficient supplies of CO/*CO and electrons at CuO sites at the working potentials, thus dramatically enhancing the formation rate of C2 products.

Investigation of rare earth elements in urine and drinking water of children in mining area.

To compare the contents of rare earth elements in urine and drinking water of children in the mining and control areas and evaluate the health risk of children in the mining area.Urine and drinking water of 128 children in the mining area and 125 children in the control area were collected from June to July 2015. The contents of rare earth elements were determined using inductively coupled plasma mass spectrometry.The detection rates of rare earth elements, including yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), and samarium (Sm), in the urine of children in the exposed group were all 100%, except for samarium (98%); the rates in the control group were 85.7%, 100%, 100%, 98%, 98%, and 59.2%, respectively, and the remaining elements were not detectable. The concentrations of Y, La, Ce, Pr, Nd, and Sm in the urine of children in the exposed group were significantly higher than that in the control group (P < .01). In addition, the composition ratio of lanthanum was higher than that in the control group. The detection rates of lanthanum and Ce in the drinking water of children in the exposed group were 1.44% and 0.72%, respectively. The others were not detectable; the rates in the control group were all 0%.The pollution caused by the presence of Y, La, Ce, Pr, Nd, and Sm in the mining area might affect the health of children in the area, but drinking water might not be the cause.