P-doped binary Ni/Fe-N-C for enhanced oxygen electrocatalysis performance.

Adjusting the micro-environment of highly dispersive metals on carbon supports has been proved to be effective for achieving enhanced electrocatalysis performance. Herein, we delicately design a phosphorus-doped binary NiFe-nitrogen-carbon material (denoted as P-NiFe-NC), taking advantage of the coupling reaction between phenylphosphonamide (P dopant) and formamide (the carbon and nitrogen sources). The XPS N 1s fine scan reveals the strong interplay of N and P by the positively shifted binding energy of pyridinic N species after P incorporation, and the chemical state of Fe species is influenced accordingly. In addition, the P doping can enlarge the specific surface area and increase the meso/macroporosity of NiFe-NC, thus contributing to the enhancement of mass transfer inside the pores. The P-NiFe-NC sample exhibits favorable bifunctional oxygen electrocatalysis performance, rendering an ORR half-wave potential of 0.85 V and an OER potential of 1.69 V@10.0 mA cm-2, superior to those of P-free NiFe-NC. Assembled into Zn-air batteries, P-NiFe-NC delivers a high specific power of 161.36 mW cm-2 and stable charge/discharge for over 100 h (corresponding to 300 cycles).

Constructing S-deficient nickel sulfide/N-doped carbon interface for improved water splitting activity.

Transition-metal sulfides are an intriguing family of electrocatalysts, yet their water-splitting applications are severely hampered by uncontrollable phase reconstruction and unsatisfactory in-service durability. Herein, we developed an efficient method to construct nickel sulfide (NiS) nanoarrays on foam nickel (NF) while being protected by highly N-doped formamide-derived carbon (termed NiS-NC@NF). The NiS nanocrystals were transformed in situ from highly dispersed Ni-N-C deposited on NF, ensuring a strong coupling effect that tunes the surface properties of NiS nanocrystals via the in situ constructed NiS/N-doped carbon interface. Electrochemical measurements reveal that very low overpotentials of 88.0 and 170.0 mV (vs. RHE) are required to achieve a current density of 10.0 mA cm-2 for hydrogen and oxygen evolution, respectively. The highly N-doped carbon matrix additionally regulates the potential-driven reconstruction of NiS in a controlled extent. Remarkably, the water electrolyzer built with NiS-NC@NF as both anode and cathode delivers an extremely low cell voltage of 1.51 V to initiate water splitting in the alkaline medium.

Nano-elemental selenium particle developed via supramolecular self-assembly of chondroitin sulfate A and Na2SeO3 to repair cartilage lesions.

Cartilage repair is a significant clinical issue due to its restricted ability to regenerate and self-heal after cartilage lesions or degenerative disease. Herein, a nano-elemental selenium particle (chondroitin sulfate A­selenium nanoparticle, CSA-SeNP) is developed by the supramolecular self-assembly of Na2SeO3 and negatively charged chondroitin sulfate A (CSA) via electrostatic interactions or hydrogen bonds followed by in-situ reducing of l-ascorbic acid for cartilage lesions repair. The constructed micelle exhibits a hydrodynamic particle size of 171.50 ± 2.40 nm and an exceptionally high selenium loading capacity (9.05 ± 0.03 %) and can promote chondrocyte proliferation, increase cartilage thickness, and improve the ultrastructure of chondrocytes and organelles. It mainly enhances the sulfation modification of chondroitin sulfate by up-regulating the expression of chondroitin sulfate 4-O sulfotransferase-1, -2, -3, which in turn promotes the expression of aggrecan to repair articular and epiphyseal-plate cartilage lesions. The micelles combine the bio-activity of CSA with selenium nanoparticles (SeNPs), which are less toxic than Na2SeO3, and low doses of CSA-SeNP are even superior to inorganic selenium in repairing cartilage lesions in rats. Thus, the developed CSA-SeNP is anticipated to be a promising selenium supplementation preparation in clinical application to address the difficulty of healing cartilage lesions with outstanding repair effects.

Highly N-Doped Fe/Co Phosphide Superstructures for Efficient Water Splitting.

Developing an inexpensive bifunctional electrocatalyst for overall water splitting is critical for acquiring scalable green hydrogen and thereby realizing carbon neutralization. Herein, an "all-in-one" method is developed for the fabrication of highly N-doped binary FeCo-phosphides (N-FeCoP) with hierarchical superstructure, this delicately designed synthesis route allows the following merits for benefiting water splitting electrocatalysis in alkaline, including high N/defect-doping for mediating the surface property of the as-made N-FeCoP, binary Fe and Co components exhibiting strong coupling interaction, and 3D hierarchical superstructure for shortening diffusion length and thereby improving reaction kinetics. Electrochemical measurements reveal that the N-FeCoP sample exhibits very low overpotentials for initiating the hydrogen and oxygen evolution reactions. Remarkably, overall water splitting can be promoted on N-FeCoP using a commercial primary Zn-MnO2 battery. The developed synthesis strategy may potentially inspire the preparation of other N-doped metal-based nanostructures for broad electrocatalysis.

Nanostructured IrO x supported on N-doped TiO2 as an efficient electrocatalyst towards acidic oxygen evolution reaction.

Reducing the Ir consumption without compromising the catalytic performance for the oxygen evolution reaction (OER) is highly paramount to promote the extensive development of the environmentally-friendly solid polymer electrolyte water electrolysis (SPEWE) system. Herein, TiO2 is doped with N through facile NH3 gas treatment and innovatively employed to support IrO x nanoparticles towards acidic OER. N-doping action not only dramatically boosts the electrical conductivity and dispersing/anchoring effects of TiO2, but also effectively improves the electron-transfer procedure. As a result, the IrO x /N-TiO2 electrocatalyst exhibits prominent catalyst utilization, catalytic activity and stability. Specifically, the overpotential required to deliver 10 mA cm-2 is only 270 mV, and the mass activity climbs to 278.7 A gIr -1 @ 1.55 VRHE. Moreover, the single cell voltage is only 1.761 V @ 2.0 A cm-2 when adopting IrO x /N-TiO2 as the anode catalyst, which is 44 mV lower than that of the commercial IrO2 counterpart.

Facile Fabrication of Transparent and Upconversion Photoluminescent Nanofiber Mats with Tunable Optical Properties.

A facile fabrication strategy of transparent and upconversion photoluminescent nylon 6 (PA6) nanofiber mats was developed based on PA6 nanofiber mats, carboxylic acid-functionalized upconversion nanoparticles (UCNP-COOH), and poly(methyl methacrylate) (PMMA) solution. UCNP-COOH were prepared by a solvothermal method, followed by the ligand exchange process. The electrospinning method and the spin-coating process were employed to combine PA6 nanofiber mats with UCNP-COOH and PMMA to introduce upconversion photoluminescent properties and transparency into the nanocomposite mats, respectively. The prepared UCNP-COOH/PA6/PMMA nanofiber mats are transparent and exhibit green emission, which are similar to UCNP-COOH when they were excited under 980 nm laser. The upconversion luminescent intensity of the functional nanofiber mats can be tailored by adjusting the weight fraction of UCNP-COOH as fillers. This facile strategy can be readily used to other types of intriguing nanocomposites for diverse applications.