Liquid crystal-nanoparticle composite systems have attracted particular attention for both academic interests and applications in inducing macroscopic alignment, altering electro-optic response of the liquid crystal hosts, and generating ordered, tunable soft metamaterials. Herein, the synthesis of two shapes of CuInS₂ nanoparticles, tremelliform-like CuInS₂ and frame-like CuInS₂, and their utilization in producing uniform homeotropic alignment of liquid crystals are reported. Through exploring the mechanism in detail, the crystal structures of CuInS₂ nanoparticles were found to rely heavily on the reaction solvents during the growth process, which in turn play a significant role on the anchor of liquid crystal molecules. The achieved homeotropic alignment shows high thermal stability, owing to the outstanding stability of the CuInS₂ nanoparticles. In addition, combining this feasible method with parallel-aligning technique, variable pretilt angles in a range of ~ 0.9º to ~ 7.2º could be continuously achieved.

Nickel based magnetic nanocrystals have been widely applied in magnetic and catalytic facilities. Tunable magnetic properties of nickel can be easily obtained via non-magnetic doping or phase transformation. However, phase transformation from face centered cubic (fcc) to hexagonal close packed (hcp) induced magnetism adjustment of Ni are always confused with nickel carbide (Ni₃C), due to the similar atomic structures of hcp-Ni and Ni₃C. Here, we present series of Au@Ni-carbide magnetic materials achieved from the controlled carbonation of Au@Ni core–shell structures, whose magnetism is tunable by adjusting the amount of carbon in the Ni layer. Ex-situ hard X-ray absorption spectroscopy (XAS) at the metal K edge and soft XAS at both metal L edge and carbon K edge provide solid evidence for the carbonation process from fcc-Ni to Ni_xC, rather than phase transformation to hcp-Ni. Further investigation reveals that the magnetism of the hybrids is mainly contributed from the residual fcc-Ni. The result represents an accurate and effective way to distinguish hexagonal Ni₃C from hcp-Ni, and provides the pathway to control magnetism of Ni-based materials for applications.

Ultrafine and highly dispersed Pd nanoparticles have drawn considerable attention with high activity, selectivity and atomic efficiency. In this paper, amorphous Pd(Ⅱ)-complex solid spheres with ~ 5 nm Pd nanoparticles loaded on were successfully achieved through a simple and gentle one-pot solution method with vitamin B1 simultaneously as complexing agent and reducing agent. An ultrathin mesoporous SiO₂ shell was then coated at the surface of Pd(Ⅱ-0) spheres as the armor which could prevent the dissolution of Pd(Ⅱ) during the catalytic process. The combination of Pd(Ⅱ) and Pd(0) endowed Pd(Ⅱ-0)@m-SiO₂ catalyst an excellent performance in eco-friendly aqueous media Suzuki reactions. The high activity, productivity and recyclability were all comparable with the best Pd catalysts ever reported. The ingenious formation of amorphous Pd(Ⅱ)/crystal Pd(0) with enhanced catalytic performances provides a new, scalable strategy to practical promotion of Suzuki cross-coupling reactions.

The growing concern for the exhaustion of fossil energy and the rapid revolution of electronics have created a rising demand for electrical energy storage devices with high energy density, for example, lithium secondary batteries (LSBs). With high surface area, low cost, excellent mechanical strength, and electrochemical stability, amorphous carbon-based materials (ACMs) have been widely investigated as promising platform for anode materials in the LSBs. In this review, we firstly summarize recent advances in the synthesis of the ACMs with various morphologies, ranging from zero- to three-dimensional structures. Then, the use of ACMs in Li-ion batteries and Li metal batteries is discussed respectively with the focus on the relationship between the structural features of the as-prepared ACMs and their roles in promoting electrochemical performances. Finally, the remaining challenges and the possible prospects for the use of ACMs in the LSBs are proposed to provide some useful clews for the future developments of this attractive area.

The current bottleneck facing further developments in fuel cells is the lack of durable electrocatalysts with satisfactory activity. In this study, a simple and fast one-pot wet-chemical method is proposed to synthesize novel Au@Pt star-like bimetallic nanocrystals (Au@Pt SLNCs) with a low Pt/Au ratio of 1:4, which show great electrocatalytic properties and outstanding stability toward the electro-oxidation reactions commonly found in fuel cells. The star-like Au core (90 ± 20 nm) is partially coated with 5 nm Pt nanocluster shells, a morphology which creates a large amount of boundaries and edges, thus tuning the surface electronic structure as demonstrated by X-ray photoelectron spectroscopy and CO-stripping measurements. This promotes excellent electrocatalytic performance towards the formic acid oxidation reaction in acidic media and the ethanol oxidation reaction in alkaline media, compared to commercial Pt or Au@Pt triangular nanoprisms, in which the Au core is fully coated by a Pt shell. Au@Pt SLNCs have the highest current density within the dehydrogenation potential range, needing the least potential to achieve a certain current density as well as the highest long-term stability. Because of the small amount of Pt usage, very fast synthesis, excellent electrocatalytic activity and durability, the proposed Au@Pt SLNCs have a promising practical application in fuel cells.

Excellent electro-optical (E-O) performances are essential for high-quality reflective cholesteric liquid crystal (LC) displays, but are often limited by the high driving voltages required by these displays. Dispersing functional nanomaterials into the LCs has emerged as a promising approach to achieve outstanding E-O properties. In this work, we report the facet-controlled E-O properties of a chiral nematic LC (N*LC) doped with cubic, octahedral, and rhombic dodecahedral Cu₂O. The outstanding E-O properties of the doped systems are related to the interaction between the liquid crystals and Cu₂O dopants with different exposed crystal planes. Doping with octahedral and rhombic dodecahedral Cu₂O reduces the stability of the planar state, as a result of both the surface abundance of active Cu atoms that interact with the polarized LC molecules, and the large amounts of vertexes and edges on the crystal surfaces, which accelerate the transition from the planar to the focal conic state under an applied electric field. Rhombic Cu₂O is the most effective dopant for improving the E-O properties of the present LCs, resulting in a 65.31% reduction of the threshold voltage. The facet and morphology effects highlighted in this work provide a new pathway to develop excellent energy-saving meso-materials with exposed high-reactivity facets, improving their potential applications in electro-optical technologies and information displays.

Nanoparticles (NPs) with flower-like and frame morphologies were synthesized from CuS, a remarkable transition-metal sulfide. We introduced two kinds of CuS NPs into a nematic liquid crystal (LC) 4-cyano-4'-n-pentylbiphenyl (5CB) and investigated the morphology- and concentration-dependent alignment and electro-optic (E-O) effects of CuS NPs on 5CB. A trace amount of flower-like CuS NPs induced a uniform homeotropic orientation of LC molecules; this is attributable to the obtained desirable compact nanosheet structure. Moreover, both flower-like and frame CuS NPs induced a remarkable improvement in the E-O properties of 5CB, and the flower-like CuS/5CB system exhibited a better performance. The doped CuS NPs in the LC host suppressed the shielding effect and strengthened the electric field, resulting in outstanding E-O properties. At a doping concentration of 0.05 wt.%, CuS NPs were well-dispersed and achieved the optimum E-O performance. This study provides a novel method for inducing a uniform orientation and enhanced E-O properties of LC molecules by doping with extraordinary CuS NPs, leading to potential applications in establishing flexible LC displays.

Manipulating the alignment of liquid crystals (LCs) is a hot and fundamental issue for their applications in block copolymers, photonics, actuators, biosensors, and liquid-crystal displays. Here, the surface characteristic of Cu₂O nanocrystals was well controlled to manipulate the orientation of the LCs. The mechanism of the orientation of the LCs induced by Cu₂O nanocrystals was elucidated based on the interaction between the LCs and Cu₂O nanocrystals. To comprehensively prove our assumption, different types of LCs (nematic, cholesteric, and smectic) as well as the same type of LCs with different polarities were selected in our system. Moreover, the photomechanical behaviors of the LC polymer composites demonstrated that the alignment of LCs can be effectively manipulated using Cu₂O nanocrystals.