Copper-Nanoparticle-Induced Porous Si/Cu Composite Films as an Anode for Lithium Ion Batteries

“Welcome-mat”-like porous Si/Cu composite amorphous films are fabricated by applying the predeposited Cu-nanoparticle-assembled film as the growth direction template for the subsequent deposition of a Si active layer with the cluster beam deposition technique. When used as the binder-free anodes for lithium ion batteries, the acquired single-layer porous Si/Cu composite film exhibits a large reversible capacity of 3124 mA h g^–1 after 1000 cycles at 1 A g^–1. Even when cycled at 20 A g^–1 for 450 cycles, the porous Si/Cu composite film still delivers a decent reversible capacity of 2086 mA h g^–1. Also, multilayer porous Si/Cu composite films are synthesized through layer-by-layer sputtering and exhibit outstanding cyclability and relatively high specific capacity and initial Coulombic efficiency irrespective of increasing the layer number from two to four layers. The reasons for the excellent electrochemical properties of single-layer and multilayer porous Si/Cu composite films are discussed in detail

Nanoring Arrays on Fe Coated Substrate: Formation and Guidance for the Growth of Hierarchical CNTs

In this article, we report the formation of nanoring structures on Fe coated substrate and their application in guiding the growth of carbon nanotube (CNT) patterns with hierarchical structures. The formation of nanorings involves the etching of polystyrene (PS) monolayer colloidal crystals (MCCs) under reactive ion etching (RIE), and the redeposition and cross-linkage of the active degradation products at the contact line between the MCCs and the substrate. After washing out the MCCs, insoluble nanorings with hexagonal order on the substrate are developed. The RIE process can control the morphology of the nanorings, as well as the distribution of the Fe element on the substrate; thus, a continuous Fe layer and separated Fe discs on the substrate are created on substrate after washing, depending on the etching time and the shield of MCCs. The surviving Fe element can work as the catalyst to initiate the in situ growth of aligned CNTs in the following chemical vapor deposition (CVD) process, while the Fe element underneath the nanorings keep its inactivity. Eventually, CNT patterns with hierarchical structures are formed. One level originates from the surviving Fe layer; the other level is templated from the nanoring structures, which cause the blank area in the CNT bundles

Electrostatic Assembly of Sandwich-like Ag-C@ZnO-C@Ag‑C Hybrid Hollow Microspheres with Excellent High-Rate Lithium Storage Properties

Herein, we introduce a facile electrostatic attraction approach to produce zinc–silver citrate hollow microspheres, followed by thermal heating treatment in argon to ingeniously synthesize sandwich-like Ag-C@ZnO-C@Ag-C hybrid hollow microspheres. The 3D carbon conductive framework in the hybrids derives from the <i>in situ</i> carbonation of carboxylate acid groups in zinc–silver citrate hollow microspheres during heating treatment, and the continuous and homogeneous Ag nanoparticles on the outer and inner surfaces of hybrid hollow microspheres endow the shells with the sandwiched configuration (Ag-C@ZnO-C@Ag-C). When applied as the anode materials for lithium ion batteries, the fabricated hybrid hollow microspheres with sandwich-like shells reveal a very large reversible capacity of 1670 mAh g^–1 after 200 cycles at a current density of 0.2 A g^–1. Even at the very large current densities of 1.6 and 10.0 A g^–1, the high specific capacities of about 1063 and 526 mAh g^–1 can be retained, respectively. The greatly enhanced electrochemical properties of Ag-C@ZnO-C@Ag-C hybrid microspheres are attributed to their special structural features such as the hollow structures, the sandwich-like shells, and the nanometer-sized building blocks

Template-Free Synthesis of Amorphous Double-Shelled Zinc–Cobalt Citrate Hollow Microspheres and Their Transformation to Crystalline ZnCo₂O₄ Microspheres

A novel and facile approach was developed for the fabrication of amorphous double-shelled zinc–cobalt citrate hollow microspheres and crystalline double-shelled ZnCo₂O₄ hollow microspheres. In this approach, amorphous double-shelled zinc–cobalt citrate hollow microspheres were prepared through a simple route and with an aging process at 70 °C. The combining inward and outward Ostwald ripening processes are adopted to account for the formation of these double-shelled architectures. The double-shelled ZnCo₂O₄ hollow microspheres can be prepared via the perfect morphology inheritance of the double-shelled zinc–cobalt citrate hollow microspheres, by calcination at 500 °C for 2 h. The resultant double-shelled ZnCo₂O₄ hollow microspheres manifest a large reversible capacity, superior cycling stability, and good rate capability

Facile Preparation of Well-Dispersed CeO₂–ZnO Composite Hollow Microspheres with Enhanced Catalytic Activity for CO Oxidation

In this article, well-dispersed CeO₂–ZnO composite hollow microspheres have been fabricated through a simple chemical reaction followed by annealing treatment. Amorphous zinc–cerium citrate hollow microspheres were first synthesized by dispersing zinc citrate hollow microspheres into cerium nitrate solution and then aging at room temperature for 1 h. By calcining the as-produced zinc–cerium citrate hollow microspheres at 500 °C for 2 h, CeO₂–ZnO composite hollow microspheres with homogeneous composition distribution could be harvested for the first time. The resulting CeO₂–ZnO composite hollow microspheres exhibit enhanced activity for CO oxidation compared with CeO₂ and ZnO, which is due to well-dispersed small CeO₂ particles on the surface of ZnO hollow microspheres and strong interaction between CeO₂ and ZnO. Moreover, when Au nanoparticles are deposited on the surface of the CeO₂–ZnO composite hollow microspheres, the full CO conversion temperature of the as-produced 1.0 wt % Au–CeO₂–ZnO composites reduces from 300 to 60 °C in comparison with CeO₂–ZnO composites. The significantly improved catalytic activity may be ascribed to the strong synergistic interplay between Au nanoparticles and CeO₂–ZnO composites