Xiaolong Yang

Bio: Xiaolong Yang is an academic researcher from Xi'an Jiaotong University. The author has contributed to research in topics: Optical burst switching & Phonon. The author has an hindex of 24, co-authored 279 publications receiving 2270 citations. Previous affiliations of Xiaolong Yang include Purdue University & University of Science and Technology Beijing.

Facile fabrication of acidified g-C3N4/g-C3N4 hybrids with enhanced photocatalysis performance under visible light irradiation

Abstract: A highly efficient visible-light-driven acidified g-C3N4 (ACNS)/g-C3N4 isotype heterojunction photocatalysts were synthesized by ultrasonic dispersion assisted electrostatic self-assembly strategy for the first time. The photocatalytic oxidation ability of the novel photocatalysts were evaluated using methyl orange (MO) as a target pollutant. The obtained ACNS/g-C3N4 photocatalysts were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectrometry (FTIR), UV–vis diffuse reflection spectroscopy (DRS), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) methods. The photocatalysts exhibited a significantly enhanced photocatalytic performance in degrading MO under visible light illumination (λ > 420 nm) compared with the pristine ACNS and g-C3N4 solely. The optimal ACNS content for the photocatalytic activity of the heterostructured composites was determined. The 30 wt.% ACNS/g-C3N4 exhibited the highest photocatalytic activity, which showed a reaction rate constant as high as 0.0216 min−1, 4.3 times higher than that of bare g-C3N4. The mechanism of the photocatalysts was investigated by determination of reactive species in the photocatalytic reactions and photoluminescence technique. The quenching effects of different scavengers displayed that the reactive h+ and O2− played major role in the reaction systems. The synergic effect between the ACNS and g-C3N4 was found to lead to an improved photo-generated carrier separation and hence the photocatalytic activities of the composite photocatalysts were increased significantly.

Mastering the surface strain of platinum catalysts for efficient electrocatalysis

Abstract: Platinum (Pt) has found wide use as an electrocatalyst for sustainable energy conversion systems1–3. The activity of Pt is controlled by its electronic structure (typically, the d-band centre), which depends sensitively on lattice strain4,5. This dependence can be exploited for catalyst design4,6–8, and the use of core–shell structures and elastic substrates has resulted in strain-engineered Pt catalysts with drastically improved electrocatalytic performances7,9–13. However, it is challenging to map in detail the strain–activity correlations in Pt-catalysed conversions, which can involve a number of distinct processes, and to identify the optimal strain modification for specific reactions. Here we show that when ultrathin Pt shells are deposited on palladium-based nanocubes, expansion and shrinkage of the nanocubes through phosphorization and dephosphorization induces strain in the Pt(100) lattice that can be adjusted from −5.1 per cent to 5.9 per cent. We use this strain control to tune the electrocatalytic activity of the Pt shells over a wide range, finding that the strain–activity correlation for the methanol oxidation reaction and hydrogen evolution reaction follows an M-shaped curve and a volcano-shaped curve, respectively. We anticipate that our approach can be used to screen out lattice strain that will optimize the performance of Pt catalysts—and potentially other metal catalysts—for a wide range of reactions. By depositing platinum shells on palladium-based nanocubes, the strain can be controlled by through phosphorization and dephosphorization, making it possible to tune the electrocatalytic activity of the platinum shells.

Inflating hollow nanocrystals through a repeated Kirkendall cavitation process.

Abstract: The Kirkendall effect has been recently used to produce hollow nanostructures by taking advantage of the different diffusion rates of species involved in the chemical transformations of nanoscale objects. Here we demonstrate a nanoscale Kirkendall cavitation process that can transform solid palladium nanocrystals into hollow palladium nanocrystals through insertion and extraction of phosphorus. The key to success in producing monometallic hollow nanocrystals is the effective extraction of phosphorus through an oxidation reaction, which promotes the outward diffusion of phosphorus from the compound nanocrystals of palladium phosphide and consequently the inward diffusion of vacancies and their coalescence into larger voids. We further demonstrate that this Kirkendall cavitation process can be repeated a number of times to gradually inflate the hollow metal nanocrystals, producing nanoshells of increased diameters and decreased thicknesses. The resulting thin palladium nanoshells exhibit enhanced catalytic activity and high durability toward formic acid oxidation.

Highly permeable and antifouling reverse osmosis membranes with acidified graphitic carbon nitride nanosheets as nanofillers

Abstract: Ultrathin graphitic carbon nitride (gCN) nanosheets, due to their two-dimensional graphene-like structure, regularly distributed triangular nanopores and structural defects on the laminar network, have attracted great research attention in fabricating high-performance water selective membranes. However, the poor dispersity of gCN limited its application in thin film nanocomposite (TFN) membranes. Here, we synthesized acidified graphitic carbon nitride (aCN) with smaller size and higher solubility. Both aCN and gCN were incorporated into a polyamide (PA) selective layer by interfacial polymerization. The aCN embedded TFN membrane (TFN-aCN) possessed supreme reverse osmosis (RO) performance among the prepared membranes. Compared with the reference TFC membrane, the TFN-aCN50 membrane exhibited a 79.3% increase in permeate flux accompanied by a quite high NaCl rejection of 98.6%. Moreover, the introduction of aCN and gCN generated a more hydrophilic and negatively charged membrane surface, and thus resulted in an improved antifouling performance.

Fast parallel algorithms for short-range molecular dynamics

Abstract: Three parallel algorithms for classical molecular dynamics are presented. The first assigns each processor a fixed subset of atoms; the second assigns each a fixed subset of inter-atomic forces to compute; the third assigns each a fixed spatial region. The algorithms are suitable for molecular dynamics models which can be difficult to parallelize efficiently—those with short-range forces where the neighbors of each atom change rapidly. They can be implemented on any distributed-memory parallel machine which allows for message-passing of data between independently executing processors. The algorithms are tested on a standard Lennard-Jones benchmark problem for system sizes ranging from 500 to 100,000,000 atoms on several parallel supercomputers--the nCUBE 2, Intel iPSC/860 and Paragon, and Cray T3D. Comparing the results to the fastest reported vectorized Cray Y-MP and C90 algorithm shows that the current generation of parallel machines is competitive with conventional vector supercomputers even for small problems. For large problems, the spatial algorithm achieves parallel efficiencies of 90% and a 1840-node Intel Paragon performs up to 165 faster than a single Cray C9O processor. Trade-offs between the three algorithms and guidelines for adapting them to more complex molecular dynamics simulations are also discussed.

Graphitic Carbon Nitride (g-C3N4)-Based Photocatalysts for Artificial Photosynthesis and Environmental Remediation: Are We a Step Closer To Achieving Sustainability?

Abstract: As a fascinating conjugated polymer, graphitic carbon nitride (g-C3N4) has become a new research hotspot and drawn broad interdisciplinary attention as a metal-free and visible-light-responsive photocatalyst in the arena of solar energy conversion and environmental remediation. This is due to its appealing electronic band structure, high physicochemical stability, and “earth-abundant” nature. This critical review summarizes a panorama of the latest progress related to the design and construction of pristine g-C3N4 and g-C3N4-based nanocomposites, including (1) nanoarchitecture design of bare g-C3N4, such as hard and soft templating approaches, supramolecular preorganization assembly, exfoliation, and template-free synthesis routes, (2) functionalization of g-C3N4 at an atomic level (elemental doping) and molecular level (copolymerization), and (3) modification of g-C3N4 with well-matched energy levels of another semiconductor or a metal as a cocatalyst to form heterojunction nanostructures. The constructi...

Gate-tunable Room-temperature Ferromagnetism in Two-dimensional Fe 3 GeTe 2

Abstract: Materials research has driven the development of modern nano-electronic devices. In particular, research in magnetic thin films has revolutionized the development of spintronic devices1,2 because identifying new magnetic materials is key to better device performance and design. Van der Waals crystals retain their chemical stability and structural integrity down to the monolayer and, being atomically thin, are readily tuned by various kinds of gate modulation3,4. Recent experiments have demonstrated that it is possible to obtain two-dimensional ferromagnetic order in insulating Cr2Ge2Te6 (ref. 5) and CrI3 (ref. 6) at low temperatures. Here we develop a device fabrication technique and isolate monolayers from the layered metallic magnet Fe3GeTe2 to study magnetotransport. We find that the itinerant ferromagnetism persists in Fe3GeTe2 down to the monolayer with an out-of-plane magnetocrystalline anisotropy. The ferromagnetic transition temperature, Tc, is suppressed relative to the bulk Tc of 205 kelvin in pristine Fe3GeTe2 thin flakes. An ionic gate, however, raises Tc to room temperature, much higher than the bulk Tc. The gate-tunable room-temperature ferromagnetism in two-dimensional Fe3GeTe2 opens up opportunities for potential voltage-controlled magnetoelectronics7-11 based on atomically thin van der Waals crystals.