Noble Metal (Pt, Rh, Pd, Ir) Doped Ru/CNT Ultra-Small Alloy for Acidic Hydrogen Evolution at High Current Density

There are still great challenges to prepare high-efficiency Ru-based catalysts that are superior to Pt/C under acidic conditions, especially under high current conditions. In this work, a series of surfactant-free noble metal doped Ru/CNT (M-Ru/CNT, M = Pt, Rh, Pd, Ir, CNT stands for carbon nanotube) are prepared by microwave reduction method in 1 minute with ≈3-3.5 nm in size for the first time. In 0.5 m H₂ SO₄ , the overpotential of Pt-Ru/CNT (Pt: 4.94 at %) is only 12 mV. What's more, it also has much larger electrochemical surface area and intrinsic activity than Pt/C. Pt-Ru/CNT still has an ultra-small overpotential under high current density (113 mV at 500 mA cm^-2 , 155 mV at 1000 mA cm^-2 ). At the same time, it possesses excellent stability regardless of high current or low current after the durability test of 100 h. Theoretical calculation also deeply reveals that Ru is the main adsorption site of H⁺ . The comparison of the electronic structure of a series of noble metals adjusted by Ru shows that Pt has the most excellent Gibbs free energy of the adsorbed hydrogen and promotes the desorption of the product.

Iron Doped in the Subsurface of CuS Nanosheets by Interionic Redox: Highly Efficient Electrocatalysts toward the Oxygen Evolution Reaction

Modifying the electronic structure of electrocatalysts by metal doping is favorable to their electrocatalytic activity. Herein, by a facile one-pot redox process of Fe(III) and Cu(I), Fe(II) was successfully doped into the subsurface of CuS nanosheets (NSs) for the first time to obtain a novel electrocatalyst (Fe_sub-CuS NSs) that possesses not only subtle lattice defects but also an atomic-level coupled nanointerface, greatly enhancing the oxygen evolution reaction (OER) performances. Meanwhile, Fe(II) and Fe(III) coexisting in Fe_sub-CuS nanosheets are favorable to OER through valence regulation. As expected, by simultaneously controlling the abovementioned three factors to optimize Fe_sub-CuS nanosheets, they display a lower overpotential of 252 mV at a current density of 20 mA cm^-2 for OER, better than 389 mV for pristine CuS nanosheets. This discovery furnishes low-cost and efficient Cu-based electrocatalysts by metal doping. Density functional theory (DFT) calculations further verify that Fe_sub-CuS(100) is thermodynamically stable and is more active for OER. This research provides a strategy for the atomic-scale engineering of nanocatalysts and also sheds light on the design of novel and efficient electrocatalysts.

Porous N-Doped Carbon Prepared from Triazine-Based Polypyrrole Network: A Highly Efficient Metal-Free Catalyst for Oxygen Reduction Reaction in Alkaline Electrolytes

Metal-free N-doped carbon (NC) materials have been regarded as one of the most promising catalysts for the oxygen reduction reaction (ORR) in alkaline media because of their outstanding ORR catalytic activity, high stability, and good methanol tolerance. Up to now, only a small minority of such catalysts have been synthesized from triazine-based polymeric networks. Herein, we report the synthesis of such NC catalyst by directly pyrolyzing a nitrogen-rich, triazine-based polypyrrole network (TPN). The TPN is fabricated by oxidative polymerization of 2,4,6-tripyrrol-1,3,5-triazine monomer using TfOH as the protonating agent and benzoyl peroxide as the oxidizing agent. The obtained NC-900 (pyrolyzed at 900 °C) catalyst exhibits excellent ORR activity in alkaline media with a high ORR onset potential (0.972 V vs RHE), a large kinetic-limiting current density (15.66 mA cm^-2 at 0.60 V), and good MeOH tolerance and durability. The as-synthesized NC-900 material is a potential candidate as a highly active, stable, and low-cost ORR catalyst for alkaline fuel cells.

Selenium-Doped Black Phosphorus for High-Responsivity 2D Photodetectors

Se-doped black phosphorus (BP) crystal, in centimeter scale, is synthesized by a scalable gas-phase growth method under mild conditions. The Se-doped BP exhibits high quality with excellent electrical properties. The Se dope induces over 20-fold enhancement of responsivity (R) for BP-based 2D photodetectors, resulting in a high R and external quantum efficiency of 15.33 A W^-1 and 2993%, respectively.

Thiourea-Modified TiO2 Nanorods with Enhanced Photocatalytic Activity

Semiconductor TiO₂ photocatalysis has attracted much attention due to its potential application in solving the problems of environmental pollution. In this paper, thiourea (CH₄N₂S) modified anatase TiO₂ nanorods were fabricated by calcination of the mixture of TiO₂ nanorods and thiourea at 600 °C for 2 h. It was found that only N element was doped into the lattice of TiO₂ nanorods. With increasing the weight ratio of thiourea to TiO₂ (R) from 0 to 8, the light-harvesting ability of the photocatalyst steady increases. Both the crystallization and photocatalytic activity of TiO₂ nanorods increase first and then decrease with increase in R value, and R2 sample showed the highest crystallization and photocatalytic activity in degradation of Brilliant Red X3B (X3B) and Rhodamine B (RhB) dyes under visible light irradiation (λ > 420 nm). The increased visible-light photocatalytic activity of the prepared N-doped TiO₂ nanorods is due to the synergistic effects of the enhanced crystallization, improved light-harvesting ability and reduced recombination rate of photo-generated electron-hole pairs. Note that the enhanced visible photocatalytic activity of N-doped nanorods is not based on the scarification of their UV photocatalytic activity.

Hierarchical porous carbon materials with high capacitance derived from Schiff-base networks

A type of hierarchical porous carbon material was prepared using a Schiff-base network as the precursor and ZnCl2 as the activation agent, and their electrochemical performances were investigated in acid and alkaline aqueous solutions, respectively. The as-prepared materials have high surface areas, appropriate distributions of hierarchical pore sizes, and various forms of nitrogen/oxygen derivatives. These structural advantages guarantee the outstanding performances of such carbon materials as electrodes for supercapacitors, which include high specific capacitances, fast current responses, and high cycling stabilities.

Characteristics of functionalized nano-hydroxyapatite and internalization by human epithelial cell

Hydroxyapatite is the main inorganic component of biological bone and tooth enamel, and synthetic hydroxyapatite has been widely used as biomaterials. In this study, a facile method has been developed for the fabrication of arginine-functionalized and europium-doped hydroxyapatite nanoparticles (Arg-Eu-HAP). The synthesized nanoparticles characterized by transmission electron microscopy, X-ray diffractometry, Fourier transform infrared, and Zeta potential analyzer. Its biological properties with DNA binding, cell toxicity, cell binding and intracellular distribution were tested by agarose gel electrophoresis assay, flow cytometry, and fluorescence microscope and laser scanning confocal microscope. The synthesized Arg-Eu-HAP could effectively bind DNA without any cytotoxicity and be internalized into the cytoplasm and perinuclear of human lung epithelial cells.

The interaction energies of cholesterol and 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine in spread mixed monolayers at the air-water interface

The interaction of cholesterol with 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) was investigated in insoluble miscible mixed monolayers at the air-water interface using a Langmuir balance technique. The strong condensation effects observed at all compositions were quantified on the basis of excess thermodynamic properties of the system. It was found that partial molar areas and work of compression of cholesterol in the mixed monolayers were greatly reduced and increased, respectively, at xDOPE of 0.8, while, in accord with the "umbrella model", the character of cholesterol monolayers was drastically affected even at mole fractions of DOPE as low as 0.2. Calculated Gibbs free energies of mixing were shown to be symmetric about equimolar lipid quantities and considerably decreased at high surface pressures. Interaction energy parameters calculated from values of excess Gibbs energy are found to decrease linearly with surface pressure at a rate of 100 kT m.N(-1), regardless of composition. All evidence points out that cholesterol-DOPE molecular interactions can be adequately simulated using a simple regular mixture model.