Ultrafine Pt Nanoparticles on Defective Tungsten Oxide for Photocatalytic Ethylene Synthesis.

The selective conversion of ethane (C2H6) to ethylene (C2H4) under mild conditions is highly wanted, yet very challenging. Herein, it is demonstrated that a Pt/WO3-x catalyst, constructed by supporting ultrafine Pt nanoparticles on the surface of oxygen-deficient tungsten oxide (WO3-x) nanoplates, is efficient and reusable for photocatalytic C2H6 dehydrogenation to produce C2H4 with high selectivity. Specifically, under pure light irradiation, the optimized Pt/WO3-x photocatalyst exhibits C2H4 and H2 yield rates of 291.8 and 373.4 µmol g-1 h-1, respectively, coupled with a small formation of CO (85.2 µmol g-1 h-1) and CH4 (19.0 µmol g-1 h-1), corresponding to a high C2H4 selectivity of 84.9%. Experimental and theoretical studies reveal that the vacancy-rich WO3-x catalyst enables broad optical harvesting to generate charge carriers by light for working the redox reactions. Meanwhile, the Pt cocatalyst reinforces adsorption of C2H6, desorption of key reaction species, and separation and migration of light-induced charges to promote the dehydrogenation reaction with high productivity and selectivity. In situ diffuse reflectance infrared Fourier transform spectroscopy and density functional theory calculation expose the key intermediates formed on the Pt/WO3-x catalyst during the reaction, which permits the construction of the possible C2H6 dehydrogenation mechanism.

Optimal concentration of Lugol's solution for detecting early esophageal carcinoma: A randomized controlled trial.

BACKGROUND AND AIM: Lugol chromoendoscopy is the standard technique to detect an esophageal squamous cell carcinoma (ESCC). However, a high concentration of Lugol's solution can induce mucosal injury and adverse events. We aimed to investigate the optimal concentration of Lugol's solution to reduce mucosal injury and adverse events without degrading image quality. METHODS: This was a two-phase double-blind randomized controlled trial. In phase I, 200 eligible patients underwent esophagogastroduodenoscopy and then were randomly (1:1:1:1:1) sprayed with 1.2%, 1.0%, 0.8%, 0.6%, or 0.4% Lugol's solution. Image quality, gastric mucosal injury, adverse events, and operation satisfaction were compared to investigate the minimal effective concentration. In phase II, 42 cases of endoscopic mucosectomy for early ESCC were included. The patients were randomly assigned (1:1) to the minimal effective (0.6%) or conventional (1.2%) concentration of Lugol's solution for further comparison of the effectiveness. RESULTS: In phase I, the gastric mucosal injury was significantly reduced in 0.6% group (P < 0.05). Furthermore, there was no statistical significance in image quality between 0.6% and higher concentrations of Lugol's solution (P > 0.05, respectively). It also showed that the operation satisfaction decreased in 1.2% group compared with the lower concentration groups (P < 0.05). In phase II, the complete resection rate was 100% in both groups, while 0.6% Lugol's solution showed higher operation satisfaction (W = 554.500, P = 0.005). CONCLUSIONS: The study indicates that 0.6% might be the optimal concentration of Lugol's solution for early detection and delineation of ESCC, considering minimal mucosal injury and satisfied image. The registry of clinical trials: ClinicalTrials.gov (NCT03180944).

Prediction of high-risk esophageal varices in patients with chronic liver disease with point and 2D shear wave elastography: a systematic review and meta-analysis.

OBJECTIVE: To assess the diagnostic performance of liver stiffness (LS) and spleen stiffness (SS) measured by point shear wave elastography (pSWE) and 2D shear wave elastography (2D-SWE) in the detection of high-risk esophageal varices (HREV) and to compare their diagnostic accuracy. METHODS: Through systematic search of PubMed, Embase, and Web of Science databases, we included 17 articles reporting the diagnostic performance of LS or SS measured by pSWE or 2D-SWE for HREV. We used a bivariate random-effects model to estimate pooled sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), area under summary receiver operator characteristic curve (AUSROC), and diagnostic odds ratio (DOR). RESULTS: For LS, there was no significant difference between the pooled sensitivity, 0.89 (95% confidence interval CI, 0.81-0.94) vs. 0.8 (95% CI, 0.72-0.86) (p = 0.13), and specificity, 0.81 (95% CI, 0.73-0.87) vs. 0.73 (95% CI, 0.65-0.79) (p = 0.07) of pSWE and 2D-SWE. The AUSROC and DOR of pSWE were higher than those of 2D-SWE: 0.92 (95% CI, 0.89-0.94) vs. 0.84 (95% CI, 0.80-0.87), p = 0.03, 33 (95% CI, 25-61) vs. 11 (95% CI, 5-22), (p < 0.01). For SS, there was no significant difference between the pooled sensitivity 0.91 (95% CI, 0.78-0.96) vs. 0.89 (95% CI, 0.80-0.94) (p = 0.43); specificity, 0.79 (95% CI, 0.72-0.84) vs. 0.72 (95% CI, 0.63-0.79) (p = 0.06); and DOR, 35 (95% CI, 13-100) vs. 20 (95% CI, 8-50) (p = 0.16) of pSWE and 2D-SWE. CONCLUSION: LS and SS measured by pSWE and 2D-SWE have good accuracy in predicting HREV. KEY POINTS: • There is modest difference between the diagnostic performance of LS and SS measured by pSWE and 2D-SWE. • LS and SS measured by pSWE and 2D-SWE both have high sensitivity, specificity, and AUSROC for the evaluation of HREV in patients with CLD. • pSWE and 2D-SWE are promising tools for noninvasive monitoring risk of esophageal varices bleeding of CLD patients.

Metal-Organic Frameworks Derived Functional Materials for Electrochemical Energy Storage and Conversion: A Mini Review.

With many apparent advantages including high surface area, tunable pore sizes and topologies, and diverse periodic organic-inorganic ingredients, metal-organic frameworks (MOFs) have been identified as versatile precursors or sacrificial templates for preparing functional materials as advanced electrodes or high-efficiency catalysts for electrochemical energy storage and conversion (EESC). In this Mini Review, we first briefly summarize the material design strategies to show the rich possibilities of the chemical compositions and physical structures of MOFs derivatives. We next highlight the latest advances focusing on the composition/structure/performance relationship and discuss their practical applications in various EESC systems, such as supercapacitors, rechargeable batteries, fuel cells, water electrolyzers, and carbon dioxide/nitrogen reduction reactions. Finally, we provide some of our own insights into the major challenges and prospective solutions of MOF-derived functional materials for EESC, hoping to shed some light on the future development of this highly exciting field.

Synthesis of N-Doped Highly Graphitic Carbon Urchin-Like Hollow Structures Loaded with Single-Ni Atoms towards Efficient CO2 Electroreduction.

The rational design of single-atom catalysts featuring excellent conductivity, highly accessible discrete active sites and favorable mass transfer is crucial for electrocatalysis but remains challenging. In this study, a reliable Ni-catalyzed and Ni-templated strategy is developed to synthesize a single-atom catalyst by transforming metallic Ni into single-Ni atoms anchored on hollow porous urchin-like (HPU) N-doped carbon (NC) (designated as Ni-NC(HPU)), which possesses high crystallinity and sufficient Ni-N4 moiety (2.4 wt %). The unique hollow thorns on the surface, good conductivity and large external surface area facilitate electron/mass transfer and exposure of single-Ni sites. As a result, the Ni-NC(HPU) catalyst exhibits remarkable activity and high stability for CO2 electroreduction. Moreover, this synthetic strategy can also be facilely extended to prepare distinct hollow porous architectures with similar components, such as the wire- and sphere-like ones.

Surface-Exposed Single-Ni Atoms with Potential-Driven Dynamic Behaviors for Highly Efficient Electrocatalytic Oxygen Evolution.

Trapping the active sites on the exterior surface of hollow supports can reduce mass transfer resistance and enhance atomic utilization. Herein, we report a facile chemical vapor deposition strategy to synthesize single-Ni atoms decorated hollow S/N-doped football-like carbon spheres (Ni SAs@S/N-FCS). Specifically, the CdS@3-aminophenol/formaldehyde is carbonized into S/N-FCS. The gas-migrated Ni species are anchored on the surface of S/N-FCS simultaneously, yielding Ni SAs@S/N-FCS. The obtained catalyst exhibits outstanding performance for alkaline oxygen evolution reaction (OER) with an overpotential of 249 mV at 10 mA cm-2 , a small Tafel slope of 56.5 mV dec-1 , and ultra-long stability up to 166 hours without obvious fading. Moreover, the potential-driven dynamic behaviors of Ni-N4 sites and the contribution of the S dopant at different locations in the matrix to the OER activity are revealed by the operando X-ray absorption spectroscopy and theoretical calculations, respectively.

Highly Efficient Electrocatalytic Oxygen Evolution Over Atomically Dispersed Synergistic Ni/Co Dual Sites.

Single-atom catalysts (SACs) are being pursued as economical electrocatalysts. However, their low active-site loading, poor interactions, and unclear catalytic mechanism call for significant advances. Herein, atomically dispersed Ni/Co dual sites anchored on nitrogen-doped carbon (a-NiCo/NC) hollow prisms are rationally designed and synthesized. Benefiting from the atomically dispersed dual-metal sites and their synergistic interactions, the obtained a-NiCo/NC sample exhibits superior electrocatalytic activity and kinetics towards the oxygen evolution reaction. Moreover, density functional theory calculations indicate that the strong synergistic interactions from heteronuclear paired Ni/Co dual sites lead to the optimization of the electronic structure and the reduced reaction energy barrier. This work provides a promising strategy for the synthesis of high-efficiency atomically dispersed dual-site SACs in the field of electrochemical energy storage and conversion.

Engineering Platinum-Cobalt Nano-alloys in Porous Nitrogen-Doped Carbon Nanotubes for Highly Efficient Electrocatalytic Hydrogen Evolution.

Highly efficient electrocatalysts are essential for the production of green hydrogen from water electrolysis. Herein, a metal-organic framework-assisted pyrolysis-replacement-reorganization approach is developed to obtain ultrafine Pt-Co alloy nanoparticles (sub-10 nm) attached on the inner and outer shells of porous nitrogen-doped carbon nanotubes (NCNT) with closed ends. During the thermal reorganization, the migration of Pt-Co nano-alloys to both surfaces ensures the maximized exposure of active sites while maintaining the robust attachment to the porous carbon matrix. Density functional theory calculations suggest a nearly thermodynamically-neutral free energy of adsorption for hydrogen intermediates and diversified active sites induced by alloying, thus resulting in a great promotion in intrinsic activity towards the hydrogen evolution reaction (HER). Benefiting from the delicate structural design and compositional modulation, the optimized Pt3 Co@NCNT electrocatalyst manifests outstanding HER activity and superior stability in both acidic and alkaline media.

Phosphorized CoNi2 S4 Yolk-Shell Spheres for Highly Efficient Hydrogen Production via Water and Urea Electrolysis.

Exploring earth-abundant electrocatalysts with excellent activity, robust stability, and multiple functions is crucial for electrolytic hydrogen generation. Porous phosphorized CoNi2 S4 yolk-shell spheres (P-CoNi2 S4 YSSs) were rationally designed and synthesized by a combined hydrothermal sulfidation and gas-phase phosphorization strategy. Benefiting from the strengthened Ni3+ /Ni2+ couple, enhanced electronic conductivity, and hollow structure, the P-CoNi2 S4 YSSs exhibit excellent activity and durability towards hydrogen/oxygen evolution and urea oxidation reactions in alkaline solution, affording low potentials of -0.135 V, 1.512 V, and 1.306 V (versus reversible hydrogen electrode) at 10 mA cm-2 , respectively. Remarkably, when used as the anode and cathode simultaneously, the P-CoNi2 S4 catalyst merely requires a cell voltage of 1.544 V in water splitting and 1.402 V in urea electrolysis to attain 10 mA cm-2 with excellent durability for 100 h, outperforming most of the reported nickel-based sulfides and even noble-metal-based electrocatalysts. This work promotes the application of sulfides in electrochemical hydrogen production and provides a feasible approach for urea-rich wastewater treatment.

Construction of Co-Mn Prussian Blue Analog Hollow Spheres for Efficient Aqueous Zn-ion Batteries.

Prussian blue analogs (PBAs) are considered as reliable and promising cathode materials for aqueous Zn-ion batteries (AZIBs), but they suffer from low capacity and poor cycling stability due to insufficient active sites and structural damage caused by the ion insertion/extraction processes. Herein, a template-engaged ion exchange approach has been developed for the synthesis of Co-substituted Mn-rich PBA hollow spheres (CoMn-PBA HSs) as cathode materials for AZIBs. Benefiting from the multiple advantageous features including hollow structure, abundant active sites, fast Zn2+ ion diffusion, and partial Co substitution, the CoMn-PBA HSs electrode shows efficient zinc ion storage properties in terms of high capacity, decent rate capability and prolonged cycle life.

Nitrogen-Doped Amorphous Zn-Carbon Multichannel Fibers for Stable Lithium Metal Anodes.

The application of lithium metal anodes for practical batteries is still impeded by safety issues and low Coulombic efficiency caused mainly by the uncontrollable growth of lithium dendrites. Herein, two types of free-standing nitrogen-doped amorphous Zn-carbon multichannel fibers are synthesized as multifunctional hosts for lithium accommodation. The 3D macroporous structures endow effectively reduced local current density, and the lithiophilic nitrogen-doped carbon and functional Zn nanoparticles serve as preferred deposition sites with low nucleation barriers to guide uniform lithium deposition. As a result, the developed anodes exhibit remarkable electrochemical properties in terms of high Coulombic efficiency for more than 500 cycles at various current densities from 1 to 5 mA cm-2 , and symmetric cells show long-term cycling duration over 2000 h. Moreover, full cells based on the developed anode and a LiFePO4 cathode also demonstrate superior rate capability and stable cycle life.

Trimetallic Spinel NiCo2-x Fex O4 Nanoboxes for Highly Efficient Electrocatalytic Oxygen Evolution.

The development of efficient and low-cost electrocatalysts toward the oxygen evolution reaction (OER) is critical for improving the efficiency of several electrochemical energy conversion and storage devices. Here, we report an elaborate design and synthesis of porous Co-based trimetallic spinel oxide nanoboxes (NiCo2-x Fex O4 NBs) by a novel metal-organic framework engaged strategy, which involves chemical etching, cation exchange, and subsequent thermal oxidation processes. Owing to the structural and compositional advantages, the optimized trimetallic NiCo2-x Fex O4 NBs (x is about 0.117) deliver superior electrocatalytic performance for OER with an overpotential of 274 mV at 10 mA cm-2 , a small Tafel slope of 42 mV dec-1 , and good stability in alkaline electrolyte, which is much better than that of Co-based bi/monometallic spinel oxides and even commercial RuO2 .

Cluster expansion Monte Carlo study of indium-aluminum segregation and homogenization in CuInSe2-CuAlSe2 pseudobinary alloys.

The influence of temperature and Al content on the segregation and homogenization behaviour of In-Al atoms in CuIn1-xAlxSe2 (CIAS) pseudobinary alloys is studied using a combination of cluster expansion Monte Carlo simulations and first-principles calculations. Such alloys are promising materials for a number of solar-energy-related applications. We found that the segregation of In-Al atoms in CIAS alloys with different Al contents occurs at relatively low temperatures. The cluster morphology of Al(In) atoms in CIAS alloys at 73 K appears in an ellipsoidal, rod-like or lamellar form, depending on the Al(In) content. The spatial distribution of In-Al atoms becomes homogeneous as the temperature increases. By determining the inhomogeneity degree σ of In-Al distributions in CIAS alloys at a series of temperatures, we found that the variation of σ with temperature (T) for all the considered CIAS alloys are sigmoidal in general and the sharp decrease in σ within a certain temperature range implies the occurrence of inhomogeneous-to-homogeneous phase transition. The inhomogeneity degree σ of CIAS alloys before or after the phase transition (phase segregation) increases as the content of Al(x) and In(1 - x) atoms gets closer. The σ(T) data points obtained by us can be well fitted with the Boltzmann function, which can give several physically meaningful parameters such as the phase transition temperature T0, temperature range of phase transition ΔT and so on. The fitted T0 and ΔT values for CIAS alloys with different Al content were proved to be reliable. The novel method for predicting the T0 and ΔT may be applied to many other binary or pseudobinary material systems with positive formation energy.

NiMn-Based Bimetal-Organic Framework Nanosheets Supported on Multi-Channel Carbon Fibers for Efficient Oxygen Electrocatalysis.

Developing noble-metal-free bifunctional oxygen electrocatalysts is of great significance for energy conversion and storage systems. Herein, we have developed a transformation method for growing NiMn-based bimetal-organic framework (NiMn-MOF) nanosheets on multi-channel carbon fibers (MCCF) as a bifunctional oxygen electrocatalyst. Owing to the desired components and architecture, the MCCF/NiMn-MOFs manifest comparable electrocatalytic performance towards oxygen reduction reaction (ORR) with the commercial Pt/C electrocatalyst and superior performance towards oxygen evolution reaction (OER) to the benchmark RuO2 electrocatalyst. X-ray absorption fine structure (XAFS) spectroscopy and density functional theory (DFT) calculations reveal that the strong synergetic effect of adjacent Ni and Mn nodes within MCCF/NiMn-MOFs effectively promotes the thermodynamic formation of key *O and *OOH intermediates over active NiO6 centers towards fast ORR and OER kinetics.

Fabrication of Heterostructured Fe2 TiO5 -TiO2 Nanocages with Enhanced Photoelectrochemical Performance for Solar Energy Conversion.

Photocatalysts with well-designed compositions and structures are desirable for achieving highly efficient solar-to-chemical energy conversion. Heterostructured semiconductor photocatalysts with advanced hollow structures possess beneficial features for promoting the activity towards photocatalytic reactions. Here we develop a facile synthetic strategy for the fabrication of Fe2 TiO5 -TiO2 nanocages (NCs) as anode materials in photoelectrochemical (PEC) water splitting cells. A hydrothermal reaction is performed to transform MIL-125(Ti) nanodisks (NDs) to Ti-Fe-O NCs, which are further converted to Fe2 TiO5 -TiO2 NCs through a post annealing process. Owing to the compositional and structural advantages, the heterostructured Fe2 TiO5 -TiO2 NCs show enhanced performance for PEC water oxidation compared with TiO2 NDs, Fe2 TiO5 nanoparticles (NPs) and Fe2 TiO5 -TiO2 NPs.

Co3 O4 Hollow Nanoparticles Embedded in Mesoporous Walls of Carbon Nanoboxes for Efficient Lithium Storage.

Confining nanostructured electrode materials in porous carbon represents an effective strategy for improving the electrochemical performance of lithium-ion batteries. Herein, we report the design and synthesis of hybrid hollow nanostructures composed of highly dispersed Co3 O4 hollow nanoparticles (sub-20 nm) embedded in the mesoporous walls of carbon nanoboxes (denoted as H-Co3 O4 @MCNBs) as an anode material for lithium-ion batteries. The facile metal-organic framework (MOF)-engaged strategy for the synthesis of H-Co3 O4 @MCNBs involves chemical etching-coordination and subsequent two-step annealing treatments. Owing to the unique structural merits including more active interfacial sites, effectively alleviated volume variation, good and stable electrical contact, and easy access of Li+ ions, the H-Co3 O4 @MCNBs exhibit excellent lithium-storage performance in terms of high specific capacity, excellent rate capability, and cycling stability.

Metal-Organic Frameworks Based Electrocatalysts for the Oxygen Reduction Reaction.

In view of the clean and sustainable energy, metal-organic frameworks (MOFs) based materials, including pristine MOFs, MOF composites, and their derivatives are emerging as unique electrocatalysts for oxygen reduction reaction (ORR). Thanks to their tunable compositions and diverse structures, efficient MOF-based materials provide new opportunities to accelerate the sluggish ORR at the cathode in fuel cells and metal-air batteries. This Minireview first provides some introduction of ORR and MOFs, followed by the classification of MOF-based electrocatalysts towards ORR. Recent breakthroughs in engineering MOF-based ORR electrocatalysts are highlighted with an emphasis on synthesis strategy, component, morphology, structure, electrocatalytic performance, and reaction mechanism. Finally, some current challenges and future perspectives for MOF-based ORR electrocatalysts are also discussed.

Determination of multi-class antibiotic residues in compost by microwave-enhanced accelerated solvent extraction and ultra performance convergence chromatography with tandem mass spectrometry.

This work reports the development and application of a multi-class compound analysis method for the determination of 20 antibiotic residues in compost. Samples were processed by microwave-enhanced accelerated solvent extraction at 120°C for 7.5 min. Salting-out homogeneous liquid-liquid extraction was used to remove water and water-soluble impurities from the extract before ultra performance convergence chromatography with tandem mass spectrometry analysis. By using the supercritical fluid (carbon dioxide) and organic solvent (methanol) as the mobile phase, the 20 antibiotics and the internal standard were well separated in 8.2 min without obvious matrix effect. Method validation was performed and good trueness (relative error in the range of ±5.0%) and precision (inter- and intraday relative standard deviations < 10.8%) were obtained. Method detection and quantitation limits were 0.8-1.9 and 2.7-7.1 ng/g, respectively. Recoveries were assessed at three concentration levels (10, 60, and 400 ng/g) and acceptable mean values (70.4-111.9%) were found. This method has also been used to analyze real samples, and the average concentrations of antibiotics (excepting the concentrations < method quantitation limits) were determined up to 123.6 ng/g. The results showed the method could be helpful for the analysis of multi-class antibiotics in environmental samples.

Efficient Electrochemical Reduction of CO2 to HCOOH over Sub-2†nm SnO2 Quantum Wires with Exposed Grain Boundaries.

Electrochemical reduction of CO2 could mitigate environmental problems originating from CO2 emission. Although grain boundaries (GBs) have been tailored to tune binding energies of reaction intermediates and consequently accelerate the CO2 reduction reaction (CO2 RR), it is challenging to exclusively clarify the correlation between GBs and enhanced reactivity in nanostructured materials with small dimension (<10 nm). Now, sub-2 nm SnO2 quantum wires (QWs) composed of individual quantum dots (QDs) and numerous GBs on the surface were synthesized and examined for CO2 RR toward HCOOH formation. In contrast to SnO2 nanoparticles (NPs) with a larger electrochemically active surface area (ECSA), the ultrathin SnO2 QWs with exposed GBs show enhanced current density (j), an improved Faradaic efficiency (FE) of over 80 % for HCOOH and ca. 90 % for C1 products as well as energy efficiency (EE) of over 50 % in a wide potential window; maximum values of FE (87.3 %) and EE (52.7 %) are achieved.

Bi2 O3 Nanosheets Grown on Multi-Channel Carbon Matrix to Catalyze Efficient CO2 Electroreduction to HCOOH.

Bi2 O3 nanosheets were grown on a conductive multiple channel carbon matrix (MCCM) for CO2 RR. The obtained electrocatalyst shows a desirable partial current density of ca. 17.7 mA cm-2 at a moderate overpotential, and it is highly selective towards HCOOH formation with Faradaic efficiency approaching 90 % in a wide potential window and its maximum value of 93.8 % at -1.256 V. It also exhibits a maximum energy efficiency of 55.3 % at an overpotential of 0.846 V and long-term stability of 12 h with negligible degradation. The superior performance is attributed to the synergistic contribution of the interwoven MCCM and the hierarchical Bi2 O3 nanosheets, where the MCCM provides an accelerated electron transfer, increased CO2 adsorption, and a high ratio of pyrrolic-N and pyridinic-N, while ultrathin Bi2 O3 nanosheets offer abundant active sites, lowered contact resistance and work function as well as a shortened diffusion pathway for electrolyte.