Synthesizing Pd-based high entropy alloy nanoclusters for enhanced oxygen reduction.

We report the synthesis of uniform Pd-based high-entropy alloy clusters via rapid Joule heating. The quinary PdMnFeCuNi clusters exhibit 4.95 times higher mass activity than the Commercial Pt/C for the oxygen reduction reaction, and outstanding stability with only 2 mV decay in the half-wave potential after 20 000 cycles of testing.

A universal strategy for green and surfactant-free synthesis of noble metal nanoparticles.

We propose a universal, green, and surfactant-free strategy to synthesize noble metal particles with high monodispersity using gaseous H2 as a reducing agent in a solution at 60 °C. The prepared Pt nanoparticles have a 24 mV more positive half-wave potential than the commercially available Pt/C in the oxygen reduction reaction, while showing high durability with negligible half-wave potential decay after 10 000 cycles of testing.

Selective edge etching of Pd metallene for enhanced formic acid electrooxidation.

We develop a facile, selective edge etching strategy to create edge sites in Pd metallene using acetic acid. The created edge sites remarkably increase the electrochemically active surface area but reduce the charge transfer resistance, resulting in significant enhancement of catalytic activity and stability toward formic acid oxidation.

Tensile-Strained Holey Pd Metallene toward Efficient and Stable Electrocatalysis.

Noble metal-based metallenes are attracting intensive attention in energy catalysis, but it is still very challenging to precisely control the surface structures of metallenes for higher catalytic properties on account of their intrinsic thermodynamic instability. Herein, the synthesis of tensile-strained holey Pd metallene by oxidative etching is reported using hydrogen peroxide, which exhibits highly enhanced catalytic activity and stability in comparison with normal Pd metallene toward both oxygen reduction reaction and formic acid oxidation. The pre-prepared Pd metallene functions as a catalyst to decompose hydrogen peroxide, and the Pd atoms in amorphous regions of Pd metallene are preferentially removed by the introduced hydrogen peroxide during the etching process. The greatly enhanced ORR activity is mainly determined by the strong electrostatic repulsion between intermediate O* and the dopant O, which balances the adsorption strength of O* on Pd sites, ultimately endowing a weakened adsorption energy of O* on TH-Pd metallene. This work creates a facile and economical strategy to precisely shape metallene-based nanoarchitectures with broad applications for energy systems and sensing devices.

Kinetically and thermodynamically controlled one-pot growth of gold nanoshells with NIR-II absorption for multimodal imaging-guided photothermal therapy.

Since the successful clinical trial of AuroShell for photothermal therapy, there is currently intense interest in developing gold-based core-shell structures with near-infrared (NIR) absorption ranging from NIR-I (650-900 nm) to NIR-II (900-1700 nm). Here, we propose a seed-mediated successive growth approach to produce gold nanoshells on the surface of the nanoscale metal-organic framework (NMOF) of UiO-66-NH2 (UiO = the University of Oslo) in one pot. The key to this strategy is to modulate the proportion of the formaldehyde (reductant) and its regulator / oxidative product of formic acid to harness the particle nucleation and growth rate within the same system. The gold nanoshells propagate through a well-oriented and controllable diffusion growth pattern (points → facets → octahedron), which has not been identified. Most strikingly, the gold nanoshells prepared hereby exhibit an exceedingly broad and strong absorption in NIR-II with a peak beyond 1300 nm and outstanding photothermal conversion efficiency of 74.0%. Owing to such superior performance, these gold nanoshells show promising outcomes in photoacoustic (PA), computed tomography (CT), and photothermal imaging-guided photothermal therapy (PTT) for breast cancer, as demonstrated both in vitro and in vivo.

Controllable Synthesis of Web-Footed PdCu Nanosheets and Their Electrocatalytic Applications.

Morphological control of noble-metal-based nanocrystals has attracted enormous attention because their catalytic behaviors can be optimized well by adjusting the size and shape. Herein, the controllable synthesis of web-footed PdCu nanosheets via a facile surfactant-free method is reported. It is discovered that the Cu(II) precursor in this synthetic system displays a critical role in growing branches along the lateral of nanosheets. This work demonstrates a Pd-based alloy nanoarchitecture for efficient and stable electrocatalysis of both ethanal and formic acid oxidation reactions.

Dynamically self-assembled adenine-mediated synthesis of pristine graphene-supported clean Pd nanoparticles with superior electrocatalytic performance toward formic acid oxidation.

Pd-based catalysts with maximized exposure of active sites, ultrafast electron transport, and cocatalyst-promoted intrinsic activity are highly desirable for the formic acid oxidation reaction (FAOR), but their fabrication presents a formidable challenge. For the first time, dynamic self-assembly of adenine has been utilized for growth of ultrasmall, highly dispersed, and clean Pd NPs on pristine graphene. The obtained nanohybrid shows remarkably enhanced FAOR catalytic activity and durability compared to Pd NPs directly grown on pristine graphene and commercial Pd/C. The activity is also among the highest for Pd-based catalysts. The excellent catalytic performance is due to well-dispersed, ultrasmall, and clean Pd NPs intimately grown on pristine graphene offering numerous electrochemically accessible active sites and preserving high intrinsic catalytic activity of Pd, great cocatalytic effect of pristine graphene enhancing CO tolerance and intrinsic activity of Pd, and robust attachment of Pd with high CO tolerance on graphene providing high durability. This study develops a facile, mild, and economical strategy to create pristine graphene supported clean Pd NPs with outstanding FAOR catalytic performance, and also sheds light on the mechanism of dynamically self-assembled adenine-mediated synthesis, which is extendable to fabricate other nanohybrids.

Directionally In Situ Self-Assembled, High-Density, Macropore-Oriented, CoP-Impregnated, 3D Hierarchical Porous Carbon Sheet Nanostructure for Superior Electrocatalysis in the Hydrogen Evolution Reaction.

3D ZIF-67-particles-impregnated cellulose-nanofiber nanosheets with oriented macropores are synthesized via directional-freezing-assisted in situ self-assembly, and converted to 3D CoP-nanoparticle (NP)-embedded hierarchical, but macropores-oriented, N-doped carbon nanosheets via calcination and phosphidation. The obtained nanoarchitecture delivers overpotentials at 10 and 50 mA cm-2 and Tafel slope of 82.1 and 113.4 mV and 40.8 mV dec-1 in 0.5 M H2 SO4 , and of 97.1 and 136.6 mV and 51.2 mV dec-1 in 1 M KOH, all of which are superior to those of the most reported non-noble-metal-based hydrogen evolution reaction (HER) catalysts. This catalyst even surpasses commercial Pt/C for a much lower overpotential at high current densities, which is essential for large-scale hydrogen production. Its catalytic activity can be further optimized to become one of the best in both 0.5 M H2 SO4 and 1 M KOH. The outstanding catalytic activity is ascribed to the uniformly-dispersed small CoP NPs in the 3D carbon sheets and the hierarchical nanostructure with rich oriented pores. This work develops a facile, economical, and universal self-assembly strategy to fabricate uniquely nanostructured hybrids to simultaneously promote charge transfer and mass transport, and also offers an inexpensive and high-performance HER catalyst toward industry-scale water splitting.

In situ self-assembled N-rich carbon on pristine graphene as a highly effective support and cocatalyst of short Pt nanoparticle chains for superior electrocatalytic activity toward methanol oxidation.

Highly conductive cocatalysts with great promotion effects are critical for the development of pristine graphene supported Pt-based catalysts for the methanol oxidation reaction (MOR) in direct methanol fuel cells (DMFCs). However, identification of these cocatalysts and controlled fabrication of Pt/cocatalyst/graphene hybrids with superior catalytic performance present great challenges. For the first time, pristine graphene supported N-rich carbon (NC) has been controllably fabricated via ionic-liquid-based in situ self-assembly for in situ growth of small and uniformly dispersed Pt NP chains to improve the MOR catalytic activity. It is discovered that the NC serves simultaneously as a linker to facilitate in situ nucleation of Pt, a stabilizer to restrict its growth and aggregation, and a structure-directing agent to induce the formation of Pt NP chains. The obtained nanohybrid shows a much higher forward peak current density than commercial Pt/C and most reported noncovalently functionalized carbon (NFC) supported Pt catalysts, a lower onset potential than almost all commercial Pt/C and NFC supported Pt, and greatly enhanced durability compared to graphene supported Pt NPs and commercial Pt/C. The superior catalytic performance is ascribed to the uniformly dispersed, small-diameter, and short Pt NP chains supported on highly conductive G@NC providing high ECSA and improved CO tolerance and the NC with high content of graphitic N greatly enhancing the intrinsic activity and CO tolerance of Pt and offering numerous binding sites for robustly attaching Pt. This work not only identifies and controllably fabricates a novel cocatalyst to significantly promote the catalytic activity of pristine graphene supported Pt but provides a facile and economical strategy for the controlled synthesis of high-performance integrated catalysts for the MOR in DMFCs.

Hierarchical defective palladium-silver alloy nanosheets for ethanol electrooxidation.

Tuning the chemical composition and surface structure of electrodes is demonstrated as a feasible and effective strategy to tailor advanced catalysts for energy electrocatalysis. In this work, hierarchical palladium-silver alloy nanosheets (PdAg NS) with the thickness ~7 atoms and rich atomic defects are successfully prepared, using the carbon monoxide (CO) confinement approach. The optimized Pd7Ag3 NS/C exhibits 8.8 times higher catalytic peak current density and much better stability toward ethanol electrooxidation than Pd NS/C catalyst. The catalytic enhancement mechanism could be attributed to the synergetic effects among optimized electronic structure of Pd, novel architecture, and rich atomic defects.

Simple and effective synthesis of zinc ferrite nanoparticle immobilized by reduced graphene oxide as anode for lithium-ion batteries.

In this work, a simple and effective method is developed to synthesize zinc ferrite nanoparticles (ZnFe2O4) in a redox coprecipitation reaction system containing only ferrous and zinc salt followed by a solid-state reaction. On this foundation, ZnFe2O4 nanoparticles with reduced size are further immobilized by reduced graphene oxide (RGO) to engineer a ZnFe2O4/RGO composite by simply introducing graphene oxide (GO) in the above reaction system. The ZnFe2O4/RGO composite electrode exhibits attractive lithium-ion storage capability with a reversible capacity of about 760 mAh·g-1 for 200 charge/discharge cycles and 603 mAh·g-1 for 700 cycles under a current rate of 1.0 A·g-1. The robust and porous RGO supporting framework, well immobilized ZnFe2O4 nanoparticles with controlled size and pseudocapacitive behavior of the composite jointly ensure the good battery performance. Moreover, the synthetic route for ZnFe2O4 nanoparticles and ZnFe2O4/RGO composite is simple and economic, which may be further developed for massive production and applied in other fields.

ZIF-67-Derived CoSe/NC Composites as Anode Materials for Lithium-Ion Batteries.

As a typical metal selenide, CoSe is a kind of foreground anode material for lithium-ion batteries (LIBs) because of its two-dimensional layer structure, good electrical conductivity, and high theoretical capacity. In this work, the original CoSe/N-doped carbon (CoSe/NC) composites were synthesized using ZIF-67 as a precursor, in which the CoSe nanoparticles are encapsulated in NC nanolayers and they are connected through C-Se bonds. The coating structure and strong chemical coupling make the NC nanolayers could better effectively enhance the lithium storage properties of CoSe/NC composites. As a consequence, the CoSe/NC composites deliver a reversible capacity of 310.11 mAh g-1 after 500 cycles at 1.0 A g-1. Besides, the CoSe/NC composites show a distinct incremental behavior of capacity.

Perforated Pd Nanosheets with Crystalline/Amorphous Heterostructures as a Highly Active Robust Catalyst toward Formic Acid Oxidation.

Perforated ultrathin Pd nanosheets with crystalline/amorphous heterostructures are rationally synthesized to offer a large electrochemically active surface area of 172.6 m2 g-1 and deliver a 5.6 times higher apparent reaction rate in comparison to commercial Pd/C, thus offering a facile confined growth method to generate superior catalysts.

γ-Fe2O3 nanoparticles stabilized by holey reduced graphene oxide as a composite anode for lithium-ion batteries.

Integrating nanoscale active materials on conductive holey reduced graphene oxide (RGO) framework is an effective strategy to synthesize composite electrode materials for advanced lithium-ion batteries. Herein, a composite of γ-Fe2O3 nanoparticles stabilized by the engineered holes on RGO was successfully synthesized by using a facile in-situ etching route, which exhibited high lithium storage performance. The fundamental insight of its enhancement mechanism was discussed. This work offers a newly route to synthesize the composite of holey RGO confined metal oxide nanoparticles for the applications in lithium ion batteries and beyond.

Hierarchical zinc oxide/reduced graphene oxide composite: Preparation route, mechanism study and lithium ion storage.

A novel and simple approach to preparing hierarchical zinc oxide/reduced graphene oxide (ZnO/RGO@RGO) composite is demonstrated using few-layered graphene oxide (GO) and metal zinc as starting materials following combined processes, including in-situ metal zinc reduction and catalyzed GO deoxygenation. Metal zinc can directly reduce GO sheets in aqueous GO suspension at room temperature to obtain a porous composite precursor (ZnO/RGO) with ZnO nanoparticles anchored on the RGO sheets. Then another RGO protecting layer is directly coated on the ZnO/RGO precursor to obtain the hierarchical ZnO/RGO@RGO composite. In this step, the exposed ZnO nanoparticles on the surface of ZnO/RGO play the role of catalyst to accelerate the deoxygenation of GO from the extra added GO aqueous suspension under mild hydrothermal condition. The reaction mechanism of metal zinc with GO aqueous suspension has been explored and the catalyst role of ZnO has been verified in this work. The prepared ZnO/RGO@RGO composite exhibited both stable cycling performance and good rate capability as anode for lithium-ion batteries. The method to prepare ZnO/RGO composite is economic and eco-friendly, and the ZnO catalyzing GO reduction opens a new approach to prepare graphene derivates.

Twisted palladium-copper nanochains toward efficient electrocatalytic oxidation of formic acid.

Twisted PdCu nanochains are synthesized successfully via a staged thermal treatment route, offering rich twin boundaries as catalytic "active sites" and modified electronic effects. Toward formic acid oxidation, the twisted PdCu nanochains hold the highest catalytic peak current density (1108.2 mA mg-1Pd) over previous reported PdCu alloy catalysts, and also much higher catalytic activity and durability comparing with Pd nanochains and commercial Pd/C. The catalytic enhancement mechanism to PdCu nanochains is proposed and discussed. Additionally, we found that the formation of PdCu nanochains follows a typical anisotropic growth approach, and the multiple steps of staged thermal treatment route displays a vital role in fabricating the unique PdCu nanochains while the introduced Cu precursors might affect the reduction rate of Pd species and act as deposition or nucleation sites for twisted structure in terms of rich twin boundaries. This work describes an efficient, low-Pd loading catalyst for electrooxidation of formic acid, and also demonstrates a universal method to fabricate other defect-rich catalysts for broad applications in energy conversion and storage systems and sensing devices.

Ir-Alloyed Ultrathin Ternary PdIrCu Nanosheet-Constructed Flower with Greatly Enhanced Catalytic Performance toward Formic Acid Electrooxidation.

Ternary metal-element alloys have been reported as efficient electrocatalysts toward various electrochemical reactions, but a unique three-dimensional (3D) Ir-alloyed ternary nanosheet-composed flower (NCF) structure has not been explored yet. Herein, an innovated 1.8 nm Ir-alloyed ultrathin ternary PdIrCu NCF structure is synthesized via one-pot solvothermal reduction without using any surfactant. The as-prepared PdIrCu/C NCF catalyst remarkably improves the stability than commercial Pd/C toward formic acid electrooxidation while resulting in significantly increased mass activity. The improvement of electrocatalytic properties depends on the introduction of Ir and Cu atoms, which greatly prevented poisoning from CO while modifying the electronic structure of Pd for increased reaction active sites and accelerated charge-transfer rate as well as facilitated mass transport by ultrathin NCF 3D structure. Therefore, this catalyst possesses a promising application prospect in electrochemical energy storage/conversion systems.

Synthesis of defect-rich palladium-tin alloy nanochain networks for formic acid oxidation.

Unique and novel Pd4Sn nanochain networks were successfully synthesized with an average diameter of 5 nm, rendering a modified Pd electronic structure with rich defects such as atomic corners, steps or ledges as catalytic active sites for great enhancement of charge transfer and electrode kinetics. The prepared Pd4Sn nanochain networks held an electrochemically active surface area as high as 119.40 m2 g-1, and exhibited higher catalytic activity and stability toward formic acid oxidation compared with Pd3Sn nanochain networks, Pd5Sn nanochain networks, Pd4Sn dendrites and Pd/C. The fundamental insight of the enhancement mechanism is discussed, and this work offers a novel, less expensive but highly active catalyst for direct formic acid fuel cells.

Role of Diabetes Mellitus on Treatment Effects in Drug-susceptible Initial Pulmonary Tuberculosis Patients in China.

We assessed the role of diabetes mellitus (DM) on treatment effects in drug-susceptible initial pulmonary tuberculosis (PTB) patients. A prospective study was conducted in eight provinces of China from October 2008 to December 2010. We enrolled 1,313 confirmed drug-susceptible initial PTB patients, and all subjects received the treatment regimen (2H3R3E3Z3/4H3R3) as recommended by the national guidelines. Of the 1,313 PTB patients, 157 (11.9%) had DM; these patients had more sputum smear-positive rates at the end of the second month [adjusted odds ratios (aOR) 2.829, 95% confidence intervals (CI) 1.783-4.490], and higher treatment failure (aOR 2.120, 95% CI 1.565-3.477) and death rates (aOR 1.536, 95% CI 1.011-2.628). DM was a contributing factor for culture-positive rates at the end of the second month and treatment failure and death of PTB patients, thus playing an unfavorable role in treatment effects of PTB.

Growing Platinum-Ruthenium-Tin ternary alloy nanoparticles on reduced graphene oxide for strong ligand effect toward enhanced ethanol oxidation reaction.

Uniform Pt1Ru0.5Sn0.5 ternary alloy nanoparticles are in situ deposited on reduced graphene oxide (Pt1Ru0.5Sn0.5-RGO) through its functional groups and defects as nucleation sites to greatly electrocatalyze ethanol oxidation reaction for much higher mass current densities, larger apparent specific current densities and better stability than commercial Pt-C catalyst (Pt-C(commer)). Mechanistic studies indicate that the excellent electrocatalytic activity and anti-poisoning are resulted from a strong ligand effect of the ternary alloy components, in which the charge transfer is boosted while decreasing the density of states close to the Fermi level of Pt to reduce bond energy between Pt and CO-like adsorbates for greatly improved anti-poisoning ability. This work holds a great promise to fabricate a high performance anode catalyst with a low Pt loading for direct ethanol fuel cells.