Electrochemically Induced Ru/CoOOH Synergistic Catalyst as Bifunctional Electrode Materials for Alkaline Overall Water Splitting.

Efficient and affordable price bifunctional electrocatalysts based on transition metal oxides for oxygen and hydrogen evolution reactions have a balanced efficiency, but it remains a significant challenge to control their activity and durability. Herein, a trace Ru (0.74 wt.%) decorated ultrathin CoOOH nanosheets (≈4 nm) supported on the surface of nickel foam (Ru/CoOOH@NF) is rationally designed via an electrochemically induced strategy to effectively drive the electrolysis of alkaline overall water splitting. The as-synthesized Ru/CoOOH@NF electrocatalysts integrate the advantages of a large number of different HER (Ru nanoclusters) and OER (CoOOH nanosheets) active sites as well as strong in-suit structure stability, thereby exhibiting exceptional catalytic activity. In particular, the ultra-low overpotential of the HER (36 mV) and the OER (264 mV) are implemented to achieve 10 mA cm-2 . Experimental and theoretical calculations also reveal that Ru/CoOOH@NF possesses high intrinsic conductivity, which facilitates electron release from H2 O and H-OH bond breakage and accelerates electron/mass transfer by regulating the charge distribution. This work provides a new avenue for the rational design of low-cost and high-activity bifunctional electrocatalysts for large-scale water-splitting technology and expects to help contribute to the creation of various hybrid electrocatalysts.

Effect of morphological evolution and aggregation of plasmonic core-shell nanostructures on solar thermal conversion.

Achieving high solar energy absorption based on nanofluids (NFs) needs further study in solar photothermal conversion technology. In this work, we performed COMSOL simulations to investigate the solar energy absorption using a core-shell nanostructure composed of the Au core and shell with different materials. The influence of the radius of the Au core, the materials of the shell, and the shell thickness on the solar absorption efficiency factor (SAEF) are systematically studied. The results show that the SAEF of the Au@Li nanoparticle with ratio of 0.5 has the highest SAEF of 1.4779, increasing 1.99 times compared to that of the bare Au nanoparticle of 0.74326 with the same radius. Moreover, the optical properties, electric field distribution, and SAEF of the Au@Li dimer are further evaluated to demonstrate the aggregation effects on SAEF. We find that the SAEF of the Au@Li dimer reaches the maximum of 4.34 with a distance around 1 nm, where the LSPR coupling effect in the nanogap is sharply enhanced 700 times irradiated by light with wavelength of 760 nm. Finally, the direct absorber solar collector performance demonstrates that Au@Li dimer NFs can collect 93% of solar energy compared to 54% for Au@Li NFs and 51% for Au NFs. This work provides the possibility to achieve more efficient solar thermal conversion, and may have potential applications in efficient solar energy harvesting and utilization.

Absorption characteristics and solar absorption capacity of Au core NR coated with various shell material.

Au nanorods (NRs) can be used to improve the performance of direct absorption solar collectors (DASCs), however, the solar absorption of Au NRs should be further improved because the absorption of Au NRs in near-infrared range is strong while the absorption in visible range is relatively weak where the solar spectrum intensity is the strongest. Based on this tissue, a composite nanostructure composed of Au core NR and Mg shell is proposed to improve the solar absorption capacity. The choice of Mg material as the shell composition is explained. By optimizing the composition structure, the enhancement effect on the absorption properties of Au@Mg NR from visible range to near-infrared range is proven by the finite element method. Furthermore, the effect of imperfect shell on absorption capacity of Au@Mg NR is discussed. Finally, the DASCs performance based on optimal Au@Mg NR nanofluids is evaluated. The results show that when the volume fraction is lower than 2 ppm and the collector depth is 2 cm, the highest solar energy harvesting capacity (>92%) using Au@Mg NRs nanofluids can be obtained, showing an excellent Au-based material for DASCs application.

Inner Co Synergizing Outer Ru Supported on Carbon Nanotubes for Efficient pH-Universal Hydrogen Evolution Catalysis.

Exploring highly active but inexpensive electrocatalysts for the hydrogen evolution reaction (HER) is of critical importance for hydrogen production from electrochemical water splitting. Herein, we report a multicomponent catalyst with exceptional activity and durability for HER, in which cobalt nanoparticles were in-situ confined inside bamboo-like carbon nanotubes (CNTs) while ultralow ruthenium loading (~ 2.6 µg per electrode area ~ cm-2) is uniformly deposited on their exterior walls (Co@CNTsǀRu). The atomic-scale structural investigations and theoretical calculations indicate that the confined inner Co and loaded outer Ru would induce charge redistribution and a synergistic electron coupling, not only optimizing the adsorption energy of H intermediates (ΔGH*) but also facilitating the electron/mass transfer. The as-developed Co@CNTsǀRu composite catalyst requires overpotentials of only 10, 32, and 63 mV to afford a current density of 10 mA cm-2 in alkaline, acidic and neutral media, respectively, representing top-level catalytic activity among all reported HER catalysts. The current work may open a new insight into the rational design of carbon-supported metal catalysts for practical applications.

Binder-Free Air Electrodes for Rechargeable Zinc-Air Batteries: Recent Progress and Future Perspectives.

Designing an efficient air electrode is of great significance for the performance of rechargeable zinc (Zn)-air batteries. However, the most widely used approach to fabricate an air electrode involves polymeric binders, which may increase the interface resistance and block electrocatalytic active sites, thus deteriorating the performance of the battery. Therefore, binder-free air electrodes have attracted more and more research interests in recent years. This article provides a comprehensive overview of the latest advancements in designing and fabricating binder-free air electrodes for electrically rechargeable Zn-air batteries. Beginning with the fundamentals of Zn-air batteries and recently reported bifunctional active catalysts, self-supported air electrodes for liquid-state and flexible solid-state Zn-air batteries are then discussed in detail. Finally, the conclusion and the challenges faced for binder-free air electrodes in Zn-air batteries are also highlighted.

Porous Carbon Architecture Assembled by Cross-Linked Carbon Leaves with Implanted Atomic Cobalt for High-Performance Li-S Batteries.

The practical application of lithium-sulfur batteries is severely hampered by the poor conductivity, polysulfide shuttle effect and sluggish reaction kinetics of sulfur cathodes. Herein, a hierarchically porous three-dimension (3D) carbon architecture assembled by cross-linked carbon leaves with implanted atomic Co-N4 has been delicately developed as an advanced sulfur host through a SiO2-mediated zeolitic imidazolate framework-L (ZIF-L) strategy. The unique 3D architectures not only provide a highly conductive network for fast electron transfer and buffer the volume change upon lithiation-delithiation process but also endow rich interface with full exposure of Co-N4 active sites to boost the lithium polysulfides adsorption and conversion. Owing to the accelerated kinetics and suppressed shuttle effect, the as-prepared sulfur cathode exhibits a superior electrochemical performance with a high reversible specific capacity of 695 mAh g-1 at 5 C and a low capacity fading rate of 0.053% per cycle over 500 cycles at 1 C. This work may provide a promising solution for the design of an advanced sulfur-based cathode toward high-performance Li-S batteries.

Vacancy Occupation-Driven Polymorphic Transformation in Cobalt Ditelluride for Boosted Oxygen Evolution Reaction.

Transition-metal dichalcogenides (TMDs) hold great potential as an advanced electrocatalyst for oxygen evolution reaction (OER), but to date the activity of transition metal telluride catalysts are demonstrated to be poor for this reaction. In this study, we report the activation of CoTe2 for OER by doping secondary anions into Te vacancies to trigger a structural transition from the hexagonal to the orthorhombic phase. The achieved orthorhombic CoTe2 with partial vacancies occupied by P-doping exhibits an exceptional OER catalytic activity with an overpotential of only 241 mV at 10 mA cm-2 and a robust stability more than 24 h. The combined experimental and theoretical studies suggest that the defective phase transformation is controllable and allows the synergism of vacancy, doping as well as the reconstructed crystallographic structure, ensuring more exposure of catalytic active sites, rapid charge transfer, and energetically favorable intermediates. This vacancy occupation-driven strategy of structural transformation can also be manipulated by S- and Se-doping, which may offer useful guidance for developing tellurides-based electrocatalyst for OER.

In Situ Biomimetic Mineralization on ZIF-8 for Smart Drug Delivery.

The exploration of metal-organic frameworks (MOFs) with good biocompatibility and physiological stability as carrier platforms for biomedical applications is of great importance but remains challenging. Herein, we developed an in situ biomimetic mineralization strategy on zeolitic imidazolate framework (ZIF) nanocrystals to construct a drug release system with favorable cytocompatibility, improved stability, and pH responsiveness. With lysozyme (Lys) wrapped on the surface of Zn-based ZIF (ZIF-8), Lys/ZIF-8 could strongly bond metal ions to promote nucleation and growth of bone-like hydroxyapatite (HAp), leading to formation of HAp@Lys/ZIF-8 composites. In vitro investigations indicate that the composites with a hollow Lys/ZIF-8 core and a HAp shell exhibited a high drug-loading efficiency (56.5%), smart pH-responsive drug delivery, cytocompatibility, and stability under physiological conditions. The proposed biomimetic mineralization strategy for designing MOFs-based composites may open a new avenue to construct advanced delivery systems in the biomedical field.

Multifunctional Electrocatalysis on a Porous N-Doped NiCo2O4@C Nanonetwork.

Developing a multifunctional electrocatalyst with eminent activity, strong durability, and cheapness for the hydrogen/oxygen evolution reaction (HER/OER) and oxygen reduction reaction (ORR) is critical to overall water splitting and regenerative fuel cells. Herein, a nitrogen-doped nanonetwork assembled by porous and defective NiCo2O4@C nanowires grown on nickel foam (N-NiCo2O4@C@NF) is crafted via biomimetic mineralization and following carbonization of phase-transited lysozyme (PTL)-coupled NiCo2O4. The as-obtained N-NiCo2O4@C@NF electrocatalysts exhibit an exceptional catalytic activity with ultralow overpotentials for the HER (42 mV) and OER (242 mV) to afford 10 mA cm-2 while maintaining good stability in alkaline media. Meanwhile, the N-NiCo2O4@C electrocatalysts presents a superior catalytic activity for ORR and a favorable four-electron pathway. The unprecedented catalytic performance arises from a highly porous structure and abundant defects and synergistic effects of components. This work may offer a new possibility in the exploration of multifunctional electrocatalysts for various energy-related electrocatalytic reactions.

Phase-Transited Lysozyme-Driven Formation of Self-Supported Co3O4@C Nanomeshes for Overall Water Splitting.

The development of highly efficient catalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of paramount importance in water splitting. Herein, a phase-transited lysozyme (PTL) is employed as the platform to synthesize nitrogen-doped Co3O4@C nanomesh with rich oxygen vacancies supported on the nickel foam (N-Co3O4@C@NF). This PTL-driven N-Co3O4@C@NF integrates the advantages of porous structure, high exposure of surface atoms, strong synergetic effect between the components and unique 3D electrode configuration, imparting exceptional activity in catalyzing both HER and OER. Remarkably, an alkaline electrolyzer assembled by N-Co3O4@C@NF as both cathode and anode delivers a current density of 10 mA cm-2 at an ultralow cell voltage of 1.40 V, which is not only much lower than that of the commercially noble Pt/C and IrO2/C catalyst couple (≈1.61 V) but also a new record for the overall water splitting. The finding may open new possibilities for the design of bifunctional electrocatalysts for application in practical water electrolysis.

Ultrafine Co Nanoparticles Encapsulated in Carbon-Nanotubes-Grafted Graphene Sheets as Advanced Electrocatalysts for the Hydrogen Evolution Reaction.

The rational design of an efficient and inexpensive electrocatalyst based on earth-abundant 3d transition metals (TMs) for the hydrogen evolution reaction still remains a significant challenge in the renewable energy area. Herein, a novel and effective approach is developed for synthesizing ultrafine Co nanoparticles encapsulated in nitrogen-doped carbon nanotubes (N-CNTs) grafted onto both sides of reduced graphene oxide (rGO) (Co@N-CNTs@rGO) by direct annealing of GO-wrapped core-shell bimetallic zeolite imidazolate frameworks. Benefiting from the uniform distribution of Co nanoparticles, the in-situ-formed highly graphitic N-CNTs@rGO, the large surface area, and the abundant porosity, the as-fabricated Co@N-CNTs@rGO composites exhibit excellent electrocatalytic hydrogen evolution reaction (HER) activity. As demonstrated in electrochemical measurements, the composites can achieve 10 mA cm-2 at low overpotential with only 108 and 87 mV in 1 m KOH and 0.5 m H2 SO4 , respectively, much better than most of the reported Co-based electrocatalysts over a wide pH range. More importantly, the synthetic strategy is versatile and can be extended to prepare other binary or even ternary TMs@N-CNTs@rGO (e.g., Co-Fe@N-CNTs@rGO and Co-Ni-Cu@N-CNTs@rGO). The strategy developed here may open a new avenue toward the development of nonprecious high-performance HER catalysts.

Metal-organic framework-derived mesoporous octahedral copper oxide/titania composites for high-performance lithium-ion batteries.

A mesoporous octahedral copper oxide@titania (CuO/TiO2) composites with core-shelled structure have been successfully fabricated via a facile and cost-effective approach, which involves two main steps: the creation of homogeneous TiO2 shell onto the octahedral Cu-based metal-organic frameworks (MOFs) template and thermal decomposition of the template at controlled temperature in the air. The design of combining CuO with the TiO2 layer within a porous octahedra structure is beneficial to integrate the advantages of different components and address the severe volume change associated with pulverization issue that exists in most metal oxides-based electrodes. When assembled as an anode material for lithium-ion batteries, the as-fabricated mesoporous CuO/TiO2 octahedra can achieve outstanding electrochemical performance in terms of a high reversible capacity (692 mAh g-1 at 100 mA g-1 for over 200 cycles) and exceptional rate capability (441 and 387 mA h g-1 at 1600 and 3200 mA g-1, respectively).

In Situ Formation of Cobalt Nitrides/Graphitic Carbon Composites as Efficient Bifunctional Electrocatalysts for Overall Water Splitting.

Developing cost-effective and highly efficient bifunctional electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is of great interest for overall water splitting but still remains a challenging issue. Herein, a self-template route is employed to fabricate a unique hybrid composite constructed by encapsulating cobalt nitride (Co5.47N) nanoparticles within three-dimensional (3D) N-doped porous carbon (Co5.47N NP@N-PC) polyhedra, which can be served as a highly active bifunctional electrocatalyst. To afford a current density of 10 mA cm-2, the as-fabricated Co5.47N NP@N-PC only requires overpotentials as low as 149 and 248 mV for HER and OER, respectively. Moreover, an electrolyzer with Co5.47N NP@N-PC electrodes as both the cathode and anode catalyst in alkaline solutions can drive a current density of 10 mA cm-2 at a cell voltage of only 1.62 V, superior to that of the Pt/IrO2 couple. The excellent electrocatalytic activity of Co5.47N NP@N-PC can be mainly ascribed to the high inherent conductivity and rich nitrogen vacancies of the Co5.47N lattice, the electronic modulation of the N-doped carbon toward Co5.47N, and the hierarchically porous structure design.

2D Protein Supramolecular Nanofilm with Exceptionally Large Area and Emergent Functions.

2D nanofilms assembled by pure protein with a macroscopic area and multiple functions can be directly formed at the air/water interface or at the solid surface at a timescale of several minutes. The multifunctionality of the nanofilm coating is demonstrated by both top-down and bottom-up micro-/nanoscale interfacial engineering, including surface modification, all-water-based photo/electron-beam lithography, and electroless deposition.

A Superhydrophobic Surface Templated by Protein Self-Assembly and Emerging Application toward Protein Crystallization.

A proteinaceous superhydrophobic material for facile protein crystallization is reported. The lysozyme phase transition is rationally manipulated to form a reliable superhydrophobic coating on virtually arbitrary material surfaces with good thermostability and mechanical robustness. Such a surface exhibits a fascinating capability to drive protein crystallization, and the protein crystal array can be facilitated in a large area at an ultralow protein concentration.

Balloon kyphoplasty with calcium phosphate cement augmentation in treatment of osteoporotic vertebral compressive fractures / 中华骨科杂志

Objective To evaluate the efficacy and safety of balloon kyphoplasty in the treatment of painful osteoporotic vertebral compressive fractures. Methods From May 2000 to June 2002, 56 consecutive procedures were performed in 30 patients of painful osteoporotic vertebral compressive fractures with intact posterior vertebral body wall. Each procedure includes bilateral insertion of inflatable balloon, fracture reduction and fulfilled with bone cement. Preoperative and postoperative symptom levels, complications and radiographic findings were recorded and analyzed. Results All 30 patients tolerated the procedure well with immediate relief of their back pain in 48 hours. The mean loss of the anterior and mid vertebral body heights were (13.6?2.3) mm, (9.2?1.4) mm preoperatively and (4.7?1.5) mm, (3.4?1.1) mm postoperatively. The mean kyphosis was improved from 23.4??5.2? to 9.2??4.7?. Cement leakage and cerebrospinal fluid leakage occurred at one level respectively and resulted in no clinical symptoms, no other complication was found. Conclusion As a promising minimally invasive surgery, balloon kyphoplasty can provide early improvement of pain and function as well as spinal alignment in treatment of painful osteoporotic compressive fractures.