Reaction-driven restructuring of defective PtSe into ultrastable catalyst for the oxygen reduction reaction.

PtM (M = S, Se, Te) dichalcogenides are promising two-dimensional materials for electronics, optoelectronics and gas sensors due to their high air stability, tunable bandgap and high carrier mobility. However, their potential as electrocatalysts for the oxygen reduction reaction (ORR) is often underestimated due to their semiconducting properties and limited surface area from van der Waals stacking. Here we show an approach for synthesizing a highly efficient and stable ORR catalyst by restructuring defective platinum diselenide (DEF-PtSe) through electrochemical cycling in an O-saturated electrolyte.

Increasing Iridium Oxide Activity for the Oxygen Evolution Reaction with Hafnium Modification.

Synthesis and implementation of highly active, stable, and affordable electrocatalysts for the oxygen evolution reaction (OER) is a major challenge in developing energy efficient and economically viable energy conversion devices such as electrolyzers, rechargeable metal-air batteries, and regenerative fuel cells. The current benchmark electrocatalyst for OER is based on iridium oxide (IrO) due to its superior performance and excellent stability. However, large scale applications using IrO are impractical due to its low abundance and high cost.

Nickel Sulfide Freestanding Holey Films as Air-Breathing Electrodes for Flexible Zn-Air Batteries.

In this work, a combination of bottom-up electrochemical deposition and top-down electrochemical etching strategies followed by a subsequent sulfuration treatment was employed to rationally synthesize a nickel sulfide (NiS ) freestanding holey film (FHF). Owing to the holey structure along with the optimal electrochemically active surface area and active sites, the as-prepared NiS FHF showed an impressive bifunctional electrocatalytic performance toward both oxygen evolution and reduction reactions. The holey and freestanding features provide the NiS FHF with promising characteristics to be used as an ideal air-breathing cathode in flexible Zn-air batteries (ZABs).

Integration of Au nanoparticles with a g-CN based heterostructure: switching charge transfer from type-II to Z-scheme for enhanced visible light photocatalysis.

Here, we demonstrate that a type-II g-C3N4 nanosheet (CNNS)/W18O49 heterostructure composite can be switched to Z-scheme through the deposition of Au nanoparticles (NPs) on the surface of CNNS. As a direct result, the designed Au/CNNS/W18O49 heterostructure shows enhanced photocatalytic performance for Cr(vi) reduction than the CNNS/W18O49 heterostructure and single components (CNNS and W18O49) under visible light irradiation.

Graphene-Supported Mesoporous Carbons Prepared with Thermally Removable Templates as Efficient Catalysts for Oxygen Electroreduction.

Graphene-supported mesoporous carbons with rich nitrogen self-doped active sites (N-MC/rGO) are prepared by direct pyrolysis of a graphene-oxide-supported polymer composite embedded with massive, evenly distributed amorphous FeOOH that serve as efficient thermally removable templates. The resulting N-MC/rGO catalysts exhibit high surface areas and apparent electrocatalytic activity for oxygen reduction reaction in alkaline media. Among the series, the sample prepared at 800 °C displays the best performance with a more positive onset potential, higher limiting currents, much higher stability, and stronger poison resistance than commercial Pt/C.

Oxygen electroreduction promoted by quasi oxygen vacancies in metal oxide nanoparticles prepared by photoinduced chlorine doping.

Quasi oxygen-deficient indium tin oxide nanoparticles (ITO NPs) were prepared by photoinduced chlorine doping, and exhibited much enhanced electrocatalytic activity for oxygen reduction reaction (ORR) in alkaline media, as compared with pristine ITO.

Mesoporous N-doped carbons prepared with thermally removable nanoparticle templates: an efficient electrocatalyst for oxygen reduction reaction.

Thermally removable nanoparticle templates were used for the fabrication of self-supported N-doped mesoporous carbons with a trace amount of Fe (Fe-N/C). Experimentally Fe-N/C was prepared by pyrolysis of poly(2-fluoroaniline) (P2FANI) containing a number of FeO(OH) nanorods that were prepared by a one-pot hydrothermal synthesis and homogeneously distributed within the polymer matrix. The FeO(OH) nanocrystals acted as rigid templates to prevent the collapse of P2FANI during the carbonization process, where a mesoporous skeleton was formed with a medium surface area of about 400 m(2)/g.

Bovine serum albumin-directed synthesis of biocompatible CdSe quantum dots and bacteria labeling.

A simple method was developed for preparing CdSe quantum dots (QDs) using a common protein (bovine serum albumin (BSA)) to sequester QD precursors (Cd(2+)) in situ. Fluorescence (FL) and absorption spectra showed that the chelating time between BSA and Cd(2+), the molar ratio of BSA/Cd(2+), temperature, and pH are the crucial factors for the quality of QDs. The average QD particle size was estimated to be about 5 nm, determined by high-resolution transmission electron microscopy.