Search

SnS nanoparticles (SnS NPs) electrostatically anchored on a 3D N-doped graphene (3DNG) network exhibit the best cycling performance reported so far for SnS-based anodes. The stronger affinity of 3DNG to SnS NPs and to the discharge product compared to pure graphene is the fundamental reason for achieving a stable electrode architecture during cycling.

The interaction of CO molecules adsorbed on Au–Rh bimetallic nanoclusters supported on an ordered thin film of Al2O3/NiAl(100) was studied, primarily with infrared reflection absorption spectroscopy and density-functional-theory calculations. The bimetallic clusters, grown by sequential deposition of vapor Au and Rh onto the Al2O3/NiAl(100) surface at 300 K, had diameters of 1.2–3.0 nm and heights of 0.4–1.2 nm; they had a fcc phase and grew in the orientation (100). The infrared absorption line for CO adsorbed on Au sites (COAu) of the bimetallic clusters at 110 K was narrow (centered about 2100 cm−1) and intense, which results largely from the small adsorption energy and large dipole moment of COAu, whereas that on Rh sites (CORh) was broad (1880–2100 cm−1) and weak, which contrasts also with its counterpart on pure Rh clusters. Upon increasing the temperature to remove COAu, the absorption line for CORh narrowed and the intensity increased; at 300 K, the line width decreased by 30–40% and the absorption intensity was enhanced by 40–60%. The former arose, after the desorption of COAu, from a decreased CO–CO interaction and inhomogeneous broadening; the latter corresponded to an enhanced dipole moment of CORh, attributed to a promoted charge transfer from the CORh-binding Rh to the neighboring Au and consequently increased charge donated from CORh to Rh. The varied IR absorption for adsorbed CO can thus serve as an indicator for the charge transfer between the components in bimetallic clusters.

Self-organized alloying of Au with Rh in nanoclusters on an ordered thin film of Al2O3/NiAl(100) was investigated via various surface probe techniques under ultrahigh-vacuum conditions and calculations based on density-functional theory. The bimetallic clusters were formed on the sequential deposition of vapors of Au and Rh onto Al2O3/NiAl(100) at 300 K. The formation was more effective on the oxide seeded with Rh, since all post-deposited Au joined the pregrown Rh clusters; for metal deposition in the reverse order, some separate Rh clusters were formed. The contrasting behavior is rationalized through the easier nucleation of Rh on the oxide surface, due to the stronger Rh-oxide and Rh-Rh bonds. The alloying in the clusters proceeded, regardless of the order of metal deposition, toward a specific structure: an fcc phase, (100) orientation and Rh core-Au shell structure. The orientation, structural ordering and lattice parameters of the Au-Rh bimetallic clusters resembled Rh clusters, rather than Au clusters, on Al2O3/NiAl(100), even with Rh in a minor proportion. The Rh-predominated core-shell structuring corresponds to the binding energies in the order Rh-Rh > Rh-Au > Au-Au. The core-shell segregation, although active, was somewhat kinetically hindered, since elevating the sample temperature induced further encapsulation of Rh. The bimetallic clusters became thermally unstable above 500 K, for which both Rh and Au atoms began to diffuse into the substrate. Moreover, the electronic structures of surface elements on the bimetallic clusters, controlled by both structural and electronic effects, show a promising reactivity.

Sodium ion batteries (SIBs) have been considered a promising alternative to lithium ion batteries for large-scale energy storage. However, their inferior electrochemical performances, especially cyclability, become the major challenge for further development of SIBs. Large volume change and sluggish diffusion kinetics are generally considered to be responsible for the fast capacity degradation. Here we report the strong chemical bonding of nanostructured Sb2S3 on sulfur-doped graphene sheets (Sb2S3/SGS) that enables a stable capacity retention of 83% for 900 cycles with high capacities and excellent rate performances. To the best of our knowledge, the cycling performance of the Sb2S3/SGS composite is superior to those reported for any other Sb-based materials for SIBs. Computational calculations demonstrate that sulfur-doped graphene (SGS) has a stronger affinity for Sb2S3 and the discharge products than pure graphene, resulting in a robust composite architecture for outstanding cycling stability. Our stu...

This paper investigates the embodied performance of ‘doing citizen science’. It examines how ‘citizen scientists’ produce scientif c data using the resources available to them, and how their socio-technical practices and emotions impact the construction of a crowdsourced data infrastructure. We found that conducting citizen science is highly emotional and experiential, but these individual experiences and feelings tend to get lost or become invisible when user-contributed data are aggregated and integrated into a big data infrastructure. While new meanings can be extracted from big data sets, the loss of individual emotional and practical elements denotes the loss of data provenance and the marginalisation of individual ef orts, motivations, and local politics, which might lead to disengaged participants, and unsustainable communities of citizen scientists. The challenges of constructing a data infrastructure for crowdsourced data therefore lie in the management of both technical and social issues which are local as well as global.Keywords: crowdsourcing, big data infrastructure, citizen science

In this paper, we focused on the study of electromagnetic (EM) wave propagation in a particular anisotropic medium—Infinity-anisotropic (IA) metamaterial. IA metamaterials, which include infinity index-anisotropic and infinity loss-anisotropic metamaterial, have the ability to suppress the diffraction limit of EM wave. Thus the deep subwavelength wave could propagate in the IA metamaterials without diffraction. Through proper design and combination of IA metamaterials, we have successfully realized a subwavelength beam splitter, a subwavelength compressor, as well as a device to transfer irradiation from a line source into multiple directional subwavelength beams. We have performed full-wave simulations to validate our designs and realized the IA metamaterial devices with the multilayer dielectric/metal structure.

The surface structures and compositions of Au-Rh bimetallic nanoclusters on an ordered thin film of Al2O3/NiAl(100) were investigated, primarily with infrared reflection absorption spectra and temperature-programmed desorption of CO as a probe molecule under ultrahigh-vacuum conditions and calculations based on density-functional theory. The bimetallic clusters were formed by sequential deposition of vapors of Au and Rh onto Al2O3/NiAl(100) at 300 K. Alloying in the clusters was active and proceeded toward a specific structure-a fcc phase, (100) orientation, and Rh core-Au shell structure, regardless of the order of metal deposition. For Au clusters incorporating deposited Rh, the Au atoms remained at the cluster surface through position exchange and became less coordinated; for deposition in reverse order, deposited Au simply decorated the surfaces of Rh clusters. Both adsorption energy and infrared absorption intensity were enhanced for CO on Au sites of the bimetallic clusters; both of them are associated with the bonding to Rh and also a decreased coordination number of CO-binding Au. These enhancements can thus serve as a fingerprint for alloying and atomic inter-diffusion in similar bimetallic systems.