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The TiO 2 has the problems of low utilization of visible light and high photogenerated carrier recombination rate. The photocatalytic activity of TiO 2 can be significantly improved by introducing F ion and narrow band gap material Ag 2 S. When F ions are present on the {001} surface of TiO 2 , surface F ions drive positively charged holes across the {001} surface, creating a synergistic effect that promotes the separation of electron-hole pairs. During the sample composite process, a certain amount of Ag will be precipitated to form an all-solid Z-type heterojunction structure of Ag 2 S, Ag and F-TiO 2 , which can improve the electron-hole separation efficiency. The results of XPS characterization confirmed the migration of F ion and the precipitation of Ag. The Ag 2 S/F-TiO 2 composite sample was referred to as AT for short, and the corresponding ratio was 1:10,1:20,1:30,1:40, the optimal sample AT 1:20 degraded 95.6% tetracycline hydrochloride within 2 hours. This work simultaneously realizes TiO 2 self-modification (synergistic effect of F ion migration and TiO 2 {001} crystal surface) and composite modification (formation of all-solid Z-type heterojunction), a new idea of studying TiO 2 self-modified cooperative heterostructures is proposed, and the good application potential of AT nanocomposites in photocatalytic water treatment technology is demonstrated. • The construction of TiO 2 {001} crystal surface and F ion migration have a synergistic effect to improve the electron-hole separation efficiency. • Ag precipitates in the reaction process and constructs a Z-type heterojunction structure with Ag 2 S and F-TiO 2. Ag acts as a bridge for electron transfer and promotes electron transfer. [ABSTRACT FROM AUTHOR]

The spinel LiMn 2 O 4 cathode material shows severe capacity degradation due to Jahn–Teller distortion and dissolution of Mn during the charge-discharge process. Herein, a series of single crystal truncated octahedral of LiFe 0.03 B x Mn 1.97−x O 4 (0≤x≤0.10) were synthesized by simple solid-state combustion combined with Fe-B co-doping, morphology and particle size controlling strategy. Through Fe-B co-doping, not only the LiFe 0.03 Mn 1.97 O 4 containing {111}, {100} and {110} planes are successfully controlled to the particles containing only {111} and {100} planes, but also the near-nanometer particles are controlled to bigger submicron sizes. It is found that Fe-B co-doping can enhance the stability of the crystal structure, inhibit Jahn-Teller distortion and reduce the dissolution of Mn. Among them, the optimized LiFe 0.03 B 0.08 Mn 1.89 O 4 forms a truncated octahedral single crystal particle with good crystallization and only {111} and {100} crystal faces, and the particle size is around 349.3 nm, showing exceptional high rate capacity and long cycle life. The LiFe 0.03 B 0.08 Mn 1.89 O 4 releases a high initial discharge capacity of 107.1 mAh/g with a capacity retention of 77.7% after 1000 cycles at 10 C, which is higher than that of the LiFe 0.03 Mn 1.97 O 4 (58.8%). Even at 20 C, LiFe 0.03 B 0.08 Mn 1.89 O 4 still achieves a high reversible specific capacity (90.4 mAh/g) and outstanding long-cycle stability (81.3%, 1000th). This work provides a scientific basis for the crystal surface control and particle size control of spinel LiMn 2 O 4 , which is of great significance for the development of the next generation of high-power lithium-ion batteries. [Display omitted] • The spinel-type LiMn2O4 was modified by the strategy combining Fe-B co-doping, regulation of crystal surface and particle size. • Through Fe-B co-doping, not only the LiFe0.03Mn1.97O4 containing {111}, {100} and {110} planes are successfully controlled to the particles containing only {111} and {100} planes, but also the near-nanometer particles are controlled to bigger submicron sizes. • The optimized truncated octahedral LiFe0.03B0.08Mn1.89O4 exhibited excellent high rate performance and long cycle life. [ABSTRACT FROM AUTHOR]

In this paper, the molecular adsorption behavior and photoelectric properties of tungsten trioxide monohydrate (WO 3 ·H 2 O) (002) crystal plane into tungsten trioxide (WO 3) (002) crystal plane were studied by Density Functional Theory (DFT) and Electrochemical Impedance Spectrum (EIS). DFT simulation shows that the adsorption active sites change from two to one after the transformation of WO 3 ·H 2 O (002) crystal plane to WO 3 (002) crystal plane, which further affects the molecular adsorption behavior of the crystal plane. The crystal plane conversion leads to the decrease of the adsorption energy of water (H 2 O) molecules and the increase of the adsorption energy of oxygen (O 2) molecules, which reduces the adverse effect of water molecules on the gas sensing performance of the material and enhances the adsorption of O 2 molecules. Like O 2 molecules and H 2 O molecules, the adsorption of four kinds of organic molecules on two crystal planes will lead to an increase in the conductivity of the crystal plane. The competitive adsorption of organic molecules with O 2 molecules leads to the decrease of the conductivity of both crystal planes. However, acetone (C 2 H 6 CO) molecules are combined in the form of hydrogen bond on the WO 3 ·H 2 O (002) crystal plane, and the contribution to the increase of the conductivity of the crystal plane is significantly higher than that of O 2 molecules. After the conversion to the WO 3 (002) crystal plane, this hydrogen bond disappears. These results were confirmed by EIS test experiments. The UV-Vis diffuse reflectance absorption spectra and photocurrent spectra show that the band gap increases after the WO 3 ·H 2 O (002) crystal plane is converted into the WO 3 (002) crystal plane. Understanding the influence of crystal plane transformation on molecular adsorption behavior and photoelectric properties is of great significance for optimizing the gas sensing properties and regulating the photoelectric properties of materials. • Crystal transformation affects the surface adsorption and photoelectric properties. • Density functional theory is used to simulate the crystal plane molecular adsorption. • The change of the active sites affects the molecular adsorption behavior. • Different molecules have competitive adsorption at the same adsorption active site. • The adsorption of molecules will change the crystal surface conductivity. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) hybrid perovskite single crystals are promising photovoltaic materials. However, the single crystals grown from solution usually respond poorly to light and other charged particles. The 2D (BDA)CsPb 2 Br 7 single crystals (BDA = 1,4-butanediamine) are grown from a supersaturated solution. The macroscopical growth steps are present on the surface, leading to a large leakage current during device operation. The surface defects are removed to expose a clean and flat surface. This well-defined crystallographic surface enables an Ohmic contact with the electrode, which minimized the dark current and baseline drift. Consequently, the assembled devices exhibit an enhanced response to LED light and X-rays, revealing the surface defect to be one of the culprits underneath the poor performance of solution-grown perovskite single crystals. • The (BDA)CsPb 2 Br 7 perovskite single crystal was grown by solution cooling method. • Surface defects worsen the detection performance of crystals for photons and X-rays. • A surface treatment method was used to remove defects and improve device performance. [ABSTRACT FROM AUTHOR]

Here in we have grown bulk single crystals of NaAu 2 for the first time to enable surface studies on the nature of the (111) bulk surface. This intermetallic compound exhibits surprisingly high catalytic activity for CO oxidation, a benchmark reaction. Theory predicts NaAu 2 to be the most thermodynamically stable composition in the Na-Au binary phase diagram and NaAu 2 has been seen to preferentially form in experiments containing Na and Au which supports this prediction. The (111) surface was also predicted to be the most stable and is nearly bulk-terminated making single crystal samples prepared with this crystallographic orientation a fitting choice. The crystal quality and surface composition of the metallographically prepared surface was determined by x-ray diffraction methods in addition to optical and electron microscopy. Image 1 • Bulk crystal growth of NaAu 2 by a modified Bridgman method; centimeter size grains. • Preparation of bulk terminated (111) surface by metallographic techniques. • Bulk (111) termination renewed by metallographic technique after surface degradation. • Surface quality characterization by x-ray techniques and electron microscopy. [ABSTRACT FROM AUTHOR]

Spinel LiMn 2 O 4 has been identified as a cathode material with extensive application potential for Li-ion batteries. However, during cycling, the Jahn−Teller effect and Mn dissolution have a substantial impact on its specific capacity and cycle span. Herein, combining Fe and Cr elements co-doping with single crystal truncated octahedron morphology is proposed to solve these problems. The Fe−Cr co-doping markedly restrains the Jahn−Teller effect, and promotes the development of crystal and selective growth of crystal surfaces in spinel LiMn 2 O 4. The high exposure (111) surfaces of the truncated octahedron reduce the dissolution of Mn, and a tiny proportion of (110) and (100) surfaces increase the diffusion channels of Li+. HAADF-STEM characterization indicates that the Fe and Cr elements largely replace the Mn atoms at the octahedral 16d site. Because of these advantages, the optimal LiFe 0.05 Cr 0.08 Mn 1.95- x O 4 (LFCMO-8) delivers excellent electrochemical performance with 119.6 mAh·g−1 discharge capacity and 78.1% capacity retention after 500 cycles at 1 C. At comparatively higher current densities of 20 C and 30 C, the superior capacity retention ratios of 79.8% and 87.3% are still achieved after 2000 cycles. Even at 40 C, the LFCMO-8 sample can still reach 98.8% capacity retention rate after 2000 cycles. After 1000 cycles at 5 C, the LFCMO-8 sample still maintained a capacity retention of 45.4% at high temperature (55 °C). ICP-OES test combined with a V-shaped tube device indicates that the Mn dissolution of LCFMO-8 only accounted for 11.8% of LiFe 0.05 Mn 1.95 O 4 (LFMO). This study serves as a meaningful reference for the preparation of high-performance LiMn 2 O 4 cathode materials. • Dual-strategy modified were used to rapidly prepared LiFe 0.05 Cr x Mn 1.95−x O 4 cathode materials. • The optimal LiFe 0.05 Cr 0.08 Mn 1.88−x O 4 exhibited excellent cycling and rate properties. • The Fe and Cr elements replaced the Mn atoms at the octahedral 16d site. [ABSTRACT FROM AUTHOR]

According to the advantages of Zn doped BST (ZBST) and Mg doped BST (MBST) films, Zn and Mg sandwiches alternate doped BST film were designed: ZBST/MBST/ZBST (ZMZ) and MBST/ZBST/MBST (MZM). The film varactors were prepared on the Pt/Ti/SiO2/Si substrate by sol-gel method, their structures and dielectric properties were investigated. X ray diffraction shows that the film is cubic perovskite structure with an average grain size of 19–35 nm, grows along (110) crystal surface and the crystallization is obviously enhanced. SEM shows that ZMZ films are more compact and finer grains than ZBST films. Compared with MBST films, MZM films have little change except that the grains are slightly smaller. When the bias voltage is 20 V and 30 V respectively, the dielectric properties of ZMZ films are similar at low frequency and high frequency. It is worth noting that the ZMZ films exhibited excellent frequency stability, which can meet the needs of tuning electronic devices. Meanwhile, the related mechanisms are also discussed. [ABSTRACT FROM AUTHOR]

We show quasicrystal formation by annealing multilayers of Al, Cu and Fe. The mechanical and surface properties of quasicrystals are affected by the parameters of annealing process. Here, multilayer Al-Cu-Fe thin film samples with different compositions were sputtered on Si/SiO 2 substrates and subjected to a two-step annealing process for different durations (5, 10 and 15 h). X-ray diffraction analyses indicated that the 15-h annealed sample had a sharper quasicrystal peak, which was more stable than any other phases. From the XRD data, the amount of each phase was calculated; the sample with longer annealing duration revealed a high amount of ψ-phase (84.3% crystallinity of quasicrystal) with a small amount of cubic Al 50 (CuFe) 50 phase. Nanoindentation tests and contact angle measurements showed that this sample also had the greatest hardness (∼11 GPa) and the highest contact angle (127°), respectively. [ABSTRACT FROM AUTHOR]

Optical Thermometry is popular among researchers because of its non-contact, high sensitivity, and fast measurement properties. In the present experiment, Er3+/Yb3+/K+ co-doped NaYF 4 nanoparticles with different K+ concentrations were synthesized by solvothermal method, and the samples showed bright upconversion green emission under the excitation of a 980 nm laser. The powder X-ray diffractometer and transmission electron microscope were used to characterize the crystal structure and its surface morphology, respectively. The spectral characteristics of nanoparticles with K+ doping concentration from 10% to 30% (Molar ratio) were investigated by fluorescence spectroscopy, and it was observed that the fluorescence intensity reached the maximum at the K+ concentration of 20%, after which the intensity weakened when the K+ content continued to increase. According to the dependence between the luminescence intensity of the sample and the laser power density and fluorescence lifetime, the intrinsic mechanism was carefully investigated. Temperature-dependent spectra of the samples were recorded in the temperature range of 315–495 K， and the maximum values of absolute sensitivity (S a) and relative sensitivity (S r) were measured at 0.0041 K−1 (455 K) and 0.9220%K−1 (315 K). The experimental results show that K+/Er3+/Yb3+ triple-doped NaYF 4 green fluorescent nanoparticles (GFNs) have good prospects for applications in display devices, temperature sensing, and other fields. • Effect of K+ tri-doping on structural, luminescence behaviour and fluorescence lifetime of the Er3+-Yb3+ codoped NaYF 4 phosphors has been discussed. • The Er3+/Yb3+/K+ triple-doped NaYF 4 phosphors presented green emission and red emission. • Based on FIR, the maximum S a and S r were 0.0041 K−1 (455 K) and 0.9220%K−1 (315 K), respectively. [ABSTRACT FROM AUTHOR]

Transition metal-based electrocatalysts are the promising candidates to substitute noble metal-based catalysts for water electrolysis, owing to its abundant earth reserves and inexpensive fabrication costs. Interface engineering and cation doping engineering are verified as the effective methods to improve the sluggish electrocatalytic performance of transition metal-based electrocatalysts. Here, we synthesized a self-supported heterostructure of Ce doped Co(OH) 2 nanosheets/CoP nanowires on the support of nickel foam (Ce-Co(OH) 2 /CoP/NF) by simple hydrothermal method, low-temperature phosphorization method. The Ce atom doping can lead to lattice distortion and abundant superficial defects on crystal surface, which will generate more active sites and faster charges transformation. The heterointerface between Ce-Co(OH) 2 and CoP also can lead to electronic structure modulation at interface domain, which not can induce much fresh active sites in this area, but can optimize the active sites to the optimal state for superior catalytic activity. Benefitting from these, it only needs the overpotentials of 253 and 56 mV to realize 10 mA/cm2 for OER and HER under 1 M KOH solution, which is much enhance than single-phased samples. As the bifunctional electrocatalyst for two-electrode system, it merely requires 1.53 V to attain 10 mA/cm2 in 1 M KOH, and it also exhibits outstanding overall water splitting performance in alkaline natural electrolyte, along with excellent catalytic long-time durability. In addition, the Ce-Co(OH) 2 /CoP/NF-based electrolyzer also could achieve energy-saving hydrogen production, and simultaneously oxidative degradation of organic materials or biomass upgrading at anode under lower voltages. This work paves a novel idea to fabricate high-efficient bifunctional electrocatalysts for energy-saving H 2 production. [Display omitted] • Self-supported Ce-Co(OH) 2 /CoP/NF was prepared via a simple and environmental strategy. • Interface strong interaction modulate the electronic structure of interfacial domain. • Ce atoms doping induces lattice distortion and abundant defects on crystal surface. • Ce-Co(OH) 2 /CoP/NF exhibits excellent bifunctional performance for OER and HER process. • The electrode possesses the good property in urea degradation and biomass upgrading. [ABSTRACT FROM AUTHOR]

Ni-rich layered LiNi 0.80 Co 0.15 Al 0.05 O 2 (NCA) cathode materials have attracted extensive attention in power lithium ion batteries on account of their high specific capacities and low voltage delay. However, they still suffer from inferior cycling stability, especially operating at a high cutoff voltage. In this paper, a surface modification strategy was proposed by utilizing Al(PO 3) 3 as a coating material to enhance the cycling performance of NCA in 2.7–4.6 V (vs. Li/Li+). The surface modification effects of Al3+ lattice doping and Al(PO 3) 3 coating were verified to be well achieved. In particular, besides the functions in stabilizing surface crystal structure of the NCA and isolating the erosion from electrolyte, the Al(PO 3) 3 coating could eliminate the residual lithium on the NCA surface to in-situ generate the Li 3 PO 3 which was conductive to the rate performance. Accordingly, the Al(PO 3) 3 -modified NCA cathode delivered excellent cycling performance, of which the initial discharge capacity was 235.9 mAh.g−1 at high cutoff voltage of 4.6 V, with a capacity retention of 71.6% after 100 cycles at 1 C. This work demonstrates the feasibility of surface modification on NCA via the phosphate coating with multiple functions, and provides an efficient approach to improve the cycling stability of Ni-rich layered cathode materials at higher cutoff voltage. [Display omitted] • The dual functions of Al doping and Al(PO 3) 3 coating are realized for NCA cathode. • The residual lithium on the NCA is removed to generate the good conductor Li 3 PO 4. • A capacity retention of 71.6% is well achieved at 1 C after 100 cycles under 4.6 V. [ABSTRACT FROM AUTHOR]

On the example of the PbTe compound we present the results of the study of the interplay between the crystallographic orientation of the surfaces of high reticular density and easy cleaving of the crystals of cubic symmetry and the shape of surface structures induced by prolonged ion sputtering. We found that in case of right combination of the crystallographic orientation of both the sputtering surface and the planes of high reticular density in the aggregate with easy cleaving of the crystals, the pyramidal structures of pseudo-hexagonal shape can be formed on the sputtering surface of cubic crystals. In case of PbTe these are the surfaces of (111) crystallographic orientation subject to the presence of sputter-resistant protective shields on them. When the protective shields are destroyed, the hexagonal structures are transformed into trihedral pyramids. The pseudo-hexagonal pyramidal structures are characterized by indistinct edges and terrace-shaped lateral facets, whereas the facets of the trihedral pyramids, into which they are transformed during the ion bombardment, are mirror-smooth. We prove that: (a) the maximally sharpened pseudo-hexagonal pyramids, ion-induced on PbTe (111) sputtering surfaces, are formed as a result of self-organization of the crystallographic planes of the family {0ī2}, the reticular density of which directly follows the reticular density of the plane of the sputtered surface; (b) the roughness of the lateral facets of pseudo-hexagonal pyramids, as well as the mirroring of the facets of the trihedral pyramids is due to the impact of crystallographic planes of the {100}family, which are the planes of the greatest reticular density and easiest cleaving for PbTe crystals. [Display omitted] • We show the formation of pseudo-hexagonal pyramids on cubic crystal sputtering surfaces. • Right combination of the planes of sputtering and easy cleaving is needed for this. • Such combination is realized on PbTe crystals with (111) sputtering surfaces. • The pseudo-hexagonal pyramids are formed by the terrace-shaped lateral facets. • They are transformed into the trihedral pyramids during prolonged sputtering. [ABSTRACT FROM AUTHOR]

g-C 3 N 4 powders with different morphology and surface charged property were obtained by acidification, oxidation and exfoliation treatment of melamine. Acid treatment converts -NH 2 group in melamine into -NH 3 NO 3 group, and further oxidation reduces the existing C N H bond, promotes the formation of C N C and N (C) 3 bond in g C 3 N 4 , and ensures the formation of layered g-C 3 N 4 structure; acid treatment and exfoliation were beneficial to increase the pore volume of g-C 3 N 4 and enhance the redox ability of g-C 3 N 4. The degradation rate of acid treated g-C 3 N 4 to Rhodamine B in visible light was 3.13 times that of untreated g-C 3 N 4 , and the degradation rate of acid treated g-C 3 N 4 to ciprofloxacin was 5.04 times that of untreated g-C 3 N 4 , further indicating that acid treated-oxidation-exfoliated treatment can improve the photocatalytic degradation effect of g-C 3 N 4 and expand the application range of g-C 3 N 4. The layered g-C 3 N 4 with different surface charges can be selectively loaded onto the semiconductor materials with exposed active crystal surfaces, providing conditions for controllable preparation of Z-type heterojunction with enhanced redox ability. • g-C 3 N 4 powders with different redox ability and surface charges was prepared. • Acid treatment promotes the formation of CNC and N-(C) 3 bonds in g-C 3 N 4. • Acid-oxidation-exfoliation can improve the photocatalytic degradation of g-C 3 N 4. [ABSTRACT FROM AUTHOR]

• ZnO nanoparticles were successfully synthesized by chemical precipitation method and doped on the surface of Co2+. • The effects of Co2+ doping on the characteristic adsorption species and optoelectronic properties of the ZnO crystal surface have been simulated by density functional theory (DFT). • The simulated data show the characteristic adsorption species of crystal plane changed before and after doping with Co2+. • The conductivity is proportional to the coverage rate before doping with Co2+, The conductivity is inversely proportional to the coverage rate after doping with Co2+. • The photocurrent spectrum fitting data is consistent with the regular of experimental data, indicating that the chemical adsorption of characteristic adsorbed O 2 and the conductivity of materials can be regulated by crystal plane Co2+ doping. The effects of Co2+ doping on the characteristic adsorption species and optoelectronic properties of the ZnO crystal plane have been simulated by Density Functional Theory (DFT). Because of the linear relationship between the Fermi level density of states and the conductivity, the conductivity is reacted by the Fermi level density of states. The simulated data show the characteristic adsorption species of crystal plane changed before and after doping with Co2+: The characteristic chemisorption species (CCS) O 2 molecules disappear after the ZnO (002) plane is doped with Co2+, CCS O 2 molecules appear after (200) plane is doped with Co2+, CCS H 2 O molecules appear after (110) plane is doped with Co2+. The conductivity decreases after doping with three crystal planes. The CCS of O 2 molecules has a significant effect on the conductivity. The CCS of H 2 O molecules has no obvious effect on the conductivity. The effect of O 2 molecular coverage rate of CCS on conductivity: The conductivity is proportional to the coverage rate of CCS before doping with Co2+, the conductivity is inversely proportional to the coverage rate of CCS after doping with Co2+. The photocurrent spectrum fitting data is consistent with the regular of experimental data, indicating that the chemical adsorption of characteristic adsorbed O 2 and the conductivity of materials can be regulated by crystal plane Co2+ doping, which plays a guiding role in regulating and making use of the characteristic O 2 absorption properties of the material plane. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) contain a variety of toxic inorganic and organic compounds, and the spent cathode materials are high quality resources of Ni, Co, Mn, and Li elements. In this case, how to efficiently deal with spent materials has become an urgent problem. In this work, the regeneration of spent ternary materials via molten salt solid-liquid method and traditional solid-solid method are studied comparatively. Ordered and uniform crystals in MS-NCM are successfully grown in liquid medium of molten salts. The regenerated TS-NCM by traditional sintering method still presents inhomogeneous larger and smaller crystals. Moreover, only regeneration by molten salt method effectively removes F-contained impurity on the surface of spent materials, and the Ni3+ and Mn3+ on the crystal surface of MS-NCM are close to the values in commercial sample (Com-NCM). After 100 cycles at 0.2 C rate, MS-NCM and TS-NCM respectively deliver 149.1 mA h g−1 and 123.2 mA h g−1, maintaining 98.1% and 84.4% of their initial capacity. MS-NCM presenting better electrochemical performance than TS-NCM is attributed to the efficient regeneration of the spent cathode material in liquid medium of molten salts. [Display omitted] • Spent NCM regeneration via solid-liquid better than traditional via solid-solid. • Uniform NCM crystals successfully re-grown in liquid medium of molten salts. • Regeneration in molten salts effectively supplement Li+ and remove F-impurity. • MS-NCM delivers much higher capacity than TS-NCM after 100 cycle. [ABSTRACT FROM AUTHOR]

• We demonstrate that multi-wavelength emission can be achieved within individual microrods. • The excitonic properties of GaZnO microrods are mediated by local Ga concentration. • Self-induced defect engineering is revealed by DFT calculations. • The geometry of ZnO microrods can be altered by Ga additive. • We establish the role of crystal facet surface energy in the growth of tapered microrods. Multi-wavelength emission in wide bandgap semiconductors is commonly achieved through ternary alloying or quantum size effects. However, multi-wavelength emission within a single microstructure is highly challenging using these approaches. Here, we demonstrate that the luminescence wavelength within individual GaZnO microrods can be tailored via defect engineering. Fast chemical vapor growth of oxygen-rich ZnO microrods with Ga 2 O 3 as an additive in the ZnO vapour leads to formation of a tapered morphology with graded distribution of Ga dopants, while the Ga incorporation does not significantly alter their crystal structure. With increasing Ga content from 1 to 6 at% from tip to base, the GaZnO microrods increase in diameter towards the substrate in accordance with the birth-and-spread mechanism. The local near-band-edge emission within single ZnO microrods, analyzed by nanoscale cathodoluminescence spectroscopy, exhibits a red shift of ~0.6 eV with increasing Ga content and exhibits signature characteristics of an excitonic emission. Density Functional Theory calculations reveal that the variation in the emission wavelength arises from bandgap narrowing due to the merging of the electronic states of Ga defect complexes with ZnO energy bands. The experimental and theoretical results demonstrate (i) the utility of using the self-regulation of defect compensation effects for band gap engineering and (ii) the possibility of multi-wavelength light sources within individual microrods. [ABSTRACT FROM AUTHOR]

• We observed peculiar form changes of micron-sized ion-induced structures on PbTe surface. • The first is transformation of the ion-induced micro-sized cones into micropyramids. • Another is formation of well-ordered ripples on the facets of micropyramids. • Cones transformation is caused by planes of easy cleavage and high reticular density. • Ripples appear due to self-organization of {111} and {110} planes forming the facets. [Display omitted] Formation and transformation of micron-sized structures on PbTe crystal surfaces under impact of low energy Ar+ ions is studied. New phenomena occurring due to interaction of energetic ions and atoms forming the main crystallographic planes of solid crystalline compounds, namely the transformation of ion-induced conical structures into pyramidal ones and the formation of facets of the micropyramids with well-ordered ripples during the process of transformation are revealed. We show that conical-pyramidal transformations occur on any PbTe sputtering surface, but the shape of pyramidal structures depends on the surface crystallographic orientation. If the pyramid originates from the ion-induced conical structure on PbTe target of (100) orientation it has the tetrahedral shape and its facets are covered with pronounced well-ordered ripples arranged in parallel to the base of the pyramid and closed at its edges. We show that: (i) micro-sized conical structures ion-induced on PbTe surface are transformed into pyramidal ones due to the tendency of the PbTe compound to the easy cleavage along crystallographic planes of high reticular density; (ii) the well-ordered ripples on the facets of the tetrahedral pyramids forming from conical structures appear due to self-organization of {111} and {110} crystallographic planes shaping pyramidal facets. [ABSTRACT FROM AUTHOR]

• Preparation of precious metal-based nanocrystalline catalysts by ion beam sputtering. • Preparation of porous hydrogen evolution membrane electrode by ultrasonic enhanced electrochemical dealloying method. • Controlling the exposed crystal surface of the porous hydrogen evolution membrane electrode can affect its electrochemical active specific surface area and hydrogen evolution activity stability. Porous carbon-supported PtNi alloy catalyst obtained by ion beam sputtering and ultrasonic-assisted electrochemical dealloying showed low Pt loading, high specific surface area, and superior hydrogen evolution activity, thereby promising for broad large-scale application in hydrogen energy. [Display omitted] The development of catalysts for high-efficient hydrogen evolution reaction (HER) is important for future sustainable energy conversion. Herein, porous carbon-supported PtNi alloy catalysts were fabricated by ion beam sputtering and ultrasonic-assisted electrochemical corrosion dealloying methods, and their performances toward the catalysis of HER were evaluated. The effects of corrosion dealloying on the hydrogen evolution activity, as well as stability, phase structure, surface composition, and active sites of PtNi alloys were analyzed by various analytical methods combined with orthogonal experiments. The results showed increased catalytic activity of HER by 51.39% after corrosion of the material in 0.2 mol/L H 2 SO 4 at 40 °C for 0.5 h. The hydrogen evolution deteriorated as Pt-loading decreased by 25.83%, and corrosion temperature displayed significant influence. The pore structure of the catalyst surface raised the relative content of the exposed Pt element, and the zero-dimensional defect generated by the Ni atom deletion led to promotion in reaction area and active sites on the catalyst surface. The interplanar spacing of alloys (NiPt) was below 3%−6% of the standard value, and the lattice compressive strain of Pt was the reason that led to improved catalytic performance of PtNi alloy catalysts. The binding energy of the Pt 4f 7/2 decreased by 0.74 eV, leading to enhanced electrochemical active sites and promoted hydrogen release. [ABSTRACT FROM AUTHOR]

• Al-doped hydroxyapatite nanorods with a large surface area were synthesized. • The surface of Al-HAp nanorods was modified with hyaluronic acid (HA). • The Al-HAp/HA compound showed a higher DOX loading capacity. In this paper, we reported Al-doped hydroxyapatite (Al-HAp) nanorods with surface functionalization of hyaluronic acid (HA) for pH-responsive delivery of doxorubicin (DOX) for cancer treatment. The specific surface area and the crystal structure of both HAp and Al-HAp are studied. It is learned that the HAp and Al-HAp have similar crystal structures, but Al-HAp shows 10% larger specific surface area than HAp, which results in 30% higher DOX loading capacity than HAp nanorods, due to the increased surface area and enlarged pore size by Al doping. Moreover, the DOX loaded Al-HAp/HA was highly pH-responsive and exhibited outstanding biocompatibility and significantly enhanced anti-cancer killing effects. [ABSTRACT FROM AUTHOR]

• Er3+–Yb3+ co-doped Na 3 Y(PO 4) 2 phosphors were investigated for optical thermometry. • The phosphor displays intense UC emissions in the red and blue region. • The phosphor has high thermal sensitivity. [Display omitted] Upconverting Er3+–Yb3+ co-doped Na 3 Y(PO 4) 2 phosphors were synthesized by employing the solution combustion method for optical thermometry application. The fundamental physicochemical properties of the prepared phosphors were examined. X-ray powder diffraction analysis and field emission scanning electron microscopy had been used to characterize the crystal structure and surface morphology of the nanophosphors, respectively. The prepared phosphors retained the monoclinic crystal structure even after the addition of the Er3+/Yb3+ dopant ions. Up-conversion (UC) luminescence studies showed that the emission bands of the prepared phosphors appear in the green and red region under 980 nm laser excitation. The green and red bands arising from the transition 2H 11/2 and 4S 3/2 , 4F 9/2 levels to the ground level (4I 15/2) in the Er3+ ions had been accomplished via analyzing the temperature dependence intensity variations. The UC mechanism had been interpreted on the grounds of laser power-induced UC properties. Temperature sensing behavior of the Na 3 Y(PO 4) 2 :Yb3+/Er3+ phosphors using the fluorescence intensity ratio of thermally and non-thermally coupled emission bands had been explored. The results exhibit that the maximum sensitivity of the thermally coupled green band was 0.0027 K−1 and of the red band was 0.0034 K−1 at 670 K and 330 K, respectively. Whereas the maximum sensitivity of the non-thermally coupled bands was 0.16 K−1. The temperature sensing results reveal the capability of the prepared phosphor Na 3 Y(PO 4):Er3+/Yb3+ in temperature sensing devices using a dual-color scheme. [ABSTRACT FROM AUTHOR]

In this paper,β-Ga 2 O 3 films were grown on epi-GaN/sapphire (0001) substrates at 600,700 and 800 °C by low pressure MOCVD, respectively.And the influences of temperature on the crystal structure, surface morphology and element chemical state were investigated.XRD analysis found that β-Ga 2 O 3 films were preferentially grown along the (−201) crystal plane, and crystal quality of the films improved with increasing temperature.AFM and SEM indicated that the surface morphology of films was obviously changed with the increasing temperature, and the surface became compact and flat.The FWHM value of XRD rocking curve at 800 °C less than those grown at 600 and 700 °C, indicating that the β-Ga 2 O 3 film grown at 800 °C has better crystal quality.XPS showed that the intensity of the Ga 2p, Ga 3d and O 1s peaks increased with temperature, and epitaxial relationship of β-Ga 2 O 3 was confirmed by HRTEM, consistent with the XRD results. • β-Ga 2 O 3 films were grown on epi-GaN/sapphire (0001) substrates by low-pressure MOCVD. • β-Ga 2 O 3 films wwere preferentially grown along the (−201) direction. • The surface morphology and crystal quality changed significantly with increasing temperature. • XPS indicated that the intensity of the Ga 2p, Ga 3d and O 1s peaks increased with increasing temperature. • The Raman analysis detected low-frequency and intermediate-frequency Raman vibration mode of β-Ga 2 O 3. [ABSTRACT FROM AUTHOR]

To improve the surface activity of molybdenum (Mo), a method combining anodizing and deoxidizing annealing in a H 2 atmosphere has been proposed to prepare nanocone-structured active Mo foils (NCSAMFs) in this paper. The morphology, composition and catalytic properties of the as-prepared NCSAMF were characterized by field-emission scanning electron microscopy (FESEM), energy dispersive spectrometry (EDS) and electrochemical measurements. Nanoconical structures were generated under a voltage of 20 V for 15 min in the optimized electrolyte, and all the oxygen atoms in the nanoconical structure layer were removed under deoxidation at 650 °C for 3 h in a H 2 atmosphere while retaining the nanoconical structure and activity. Compared with the Mo foils treated under different conditions, the NCSAMFs exhibit superior hydrogen evolution reaction (HER) activity with a low onset overpotential of 123 mV and a Tafel slope of 96 mV dec−1, indicating that the NCSAMFs possess high activity and outstanding long-term stability in acidic media. Therefore, the NCSAMFs prepared in this paper are promising transition metal HER electrocatalysts and serve as active matrix materials for Mo-based materials. In addition, the surface energies of the NCSAMF and the Mo foils without nanotreatment were calculated at the atomic and mesoscopic scales, respectively, to provide more insights into the origin of the studied process, and the calculation results demonstrate that the high activity of NCSAMFs is mainly derived from the increase in Mo crystal surface area with high surface energy caused by the nanotreatment and the corresponding increase in the amount of active sites. Image 1 • Molybdenum foils were anodized in NH 4 F electrolytes to prepare a nanocones on the surface. • A deoxiding annealing process is carried out to obtain nanocone-structured active Mo foils (NCSAMFs). • The electrochemical catalytic activity is tested. • The surface energies are calculated at atomic and mesoscopic scales, respectively. [ABSTRACT FROM AUTHOR]

The relationship between crystal facet and anticorrosion performance is studied by controlling the microstructure of hydroxyapatite (HAP). HAP in shape of rectangular plate exposing (002) facets promotes it exerting anticorrosion activity. The displacement reaction occurs between OH− groups on (002) facet and corrosive Cl−, which reduces the corrosion rate. At the same time, anion exchange forms a stable chlorapatite to further enhance shielding effect of coatings. Moreover, self-supporting mechanism is proposed to explain the conversion between tetracalcium phosphate (TTCP) and HAP is benefited to making up for HAP consumed in the anticorrosion process. The rectangular plate-like HAP also prolongs the diffusion path of corrosive substances. Therefore, HAP with bare (002) facet raises the impedance by 110.3% compared with common HAP with exposed (300) facet. This research provides a direction for reducing the consumption and effective use of materials in the coatings industry. Image 1 • HAP with exposed (002) facet by adjusting synthesis is obtained to promote anticorrosion activity. • Anion exchange between OH- on (002) facet and Cl- reduces corrosion rate. • The chlorapatite formed through ion displacement improves shielding performance. • Self-supporting mechanism of conversion from TTCP to HAP is proposed. • This study provides reference for reducing consumption and effective use of materials. [ABSTRACT FROM AUTHOR]

Because of its excellent safety and sustainability, spinel-structured lithium titanate (LTO, Li 4 Ti 5 O 12) has recently attracted intensive attention as a promising anode material for lithium-ion batteries (LIBs) for large-scale applications. However, several obstacles impede the use of LTO in practical applications, including its high cost and relatively low capacity due to poor electron conductivity. To reduce the synthesis cost and increase the efficiency of LTO, LTO microspheres assembled with nanoparticles were prepared from a titanium(IV) oxysulfate (TiOSO 4) solution, which is generally produced during the sulfate process in titanium mining of ilmenite (FeTiO 3). Before LTO microspheres were synthesized, 1–2 μm microsphere scaffolds consisting of TiO 2 nanoparticles were prepared through the urea-based hydrolysis of TiOSO 4. The LTO microspheres were obtained through a sequential hydrothermal reaction–calcination process using LiOH and the as-prepared TiO 2 microsphere scaffolds. According to the synthesis conditions, LTO–TiO 2 (LTO-500), nonporous LTO (LTO-800), and porous LTO (LTO-HT3-500) microspheres were synthesized. The electrochemical performances of the synthesized LTO microspheres were most strongly affected by the microspheres' crystal size and surface area. The presence of TiO 2 in the LTO microspheres also affected their performance. The LTO-HT3-500 microspheres (pure spinel LTO phase) showed an excellent initial discharge capacity of 158.7 mAh/g, superior cyclic ability (<7.3% capacity decay, 100 cycles at 1C), and rate capability (capacity loss 11%) at high current rates (0.1C–10C) because of their small crystal size (17.6 nm) and large specific surface area (44.4 m2/g). These results demonstrate that high-performance LTO microspheres for LIBs can be produced from TiOSO 4 solution as a low-cost Ti source. Image 1 • 3D structured lithium titanate(LTO) was prepared from TiOSO 4 for lithium ion battery. • TiOSO 4 is inexpensive titanium(Ti)-source commonly produced from Ti-mining process. • Porous TiO 2 microsphere scaffold was prepared by urea based hydrolysis of TiOSO 4. • Through several hydrothermal-calcination processes, LTO microsphere was prepared. • The LTO microsphere prepared from TiOSO 4 shows excellent cyclic and rate capability. [ABSTRACT FROM AUTHOR]

In this study, α-zirconium phosphate (α-ZrP) is used as an accelerator for phosphate coatings on carbon steel. A more compact phosphate coating with enhanced corrosion resistance is obtained with the incorporation of α-ZrP. Scanning electron microscopy (SEM) was used to observe the growth of phosphate crystals and the surface morphology of phosphate coatings during the phosphating process. The phosphate crystals composition was analyzed by X-ray diffraction (XRD) spectra. Coating weight and surface roughness tests were also performed. Results of all these characterizations reveal that the incorporation of α-ZrP reduces the phosphate crystals size, coating weight and decreases coating roughness. The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests demonstrate that the incorporation of α-ZrP effectively improves corrosion resistance of phosphate coatings (i.e. the corrosion rate is decreased by one order of magnitude). Optimally when the concentration of α-ZrP in the phosphating solution is 0.8 g/L, the minimum corrosion rate (0.17 mpy) is obtained. Image 1 • α-zirconium phosphate (α-ZrP) is used as a new eco-friendly accelerator of phosphate coatings. • α-ZrP effectively increase phosphating efficiency, reduce the phosphate grain size, and form a denser phosphate coating. • α-ZrP increases the corrosion resistance of phosphate coating by one order of magnitude. [ABSTRACT FROM AUTHOR]

Some dendritic structures with well-dispersed active sites exposed can often act as electrocatalysts. In this paper, we have developed a kind of composite electrocatalyst Ni:Fe = 7.5:2.5/CF (copper foil) with dendritic FeNi 3 phase prepared by electrodeposition for OER (oxygen evolution reaction). The synthetic material with more crystal surface area and more metal active sites exposed exhibits an excellent electrocatalytic activity. The Ni:Fe = 7.5:2.5/CF electrode sample can drive the OER reaction with the overpotential(ƞ) of 330 mV at 15 mA cm−2 and 490 mV at 50 mA cm−2 respectively. And there is no significant overpotential increase for the Ni:Fe = 7.5:2.5/CF sample at the end of 50000s. The composite synergistic effect between the high active FeNi 3 phase, dendritic morphology and copper foil substrate are the main reason for its excellent electrocatalytic activity. • Electrochemical deposition is one relatively simple synthesis process for electrocatalysts. • The Ni:Fe = 7.5:2.5/CF composite can use the overpotential(ƞ) of 330 mV to drive 15 mA cm−2. • There is no significant overpotential increase for the Ni:Fe = 7.5:2.5/CF at the end of 50000s. • This is mainly attributed to the structure of containing the FeNi 3 dendrite phase. [ABSTRACT FROM AUTHOR]

VO 2 microrods (MRs) have been successfully synthesized by the reduction of V 2 O 5 thin films. The effects of reduction temperature and thickness of the precursor V 2 O 5 thin films on the stochiometry and morphology of the resulting VO 2 MRs have been studied in this work. Results show that size of the VO 2 MRs increases with increasing precursor thickness due to the enlargement of the droplets during the melting of V 2 O 5 thin films. Further, the growth of VO 2 MRs from V 2 O 5 droplets on a sapphire substrate form a unique angle between each other, which is probably due to epitaxial growth. Reduction temperatures between 600 °C and 650 °C are preferred for the growth of VO 2 MRs, while temperatures lower or higher than this range produce V 2 O 5 nanostructures or VO 2 nanoparticles, respectively. HRTEM shows that during VO 2 MR's growth, the (110) plane remains parallel to the Si substrate, and a 10 nm amorphous interface was formed between the VO 2 MR and the Si substrate. Optical properties of the MRs were examined by carrying out light scattering experiments as a function of temperature to identify the temperature range of insulator-to-metal (IM) and metal-to-insulator (MI) transition characteristics. The optical scattering experiments show the large influence of microrod (MR) size and distribution on the characteristics of MI and IM transitions. The transition behavior can range from polycrystalline film type transition to new unique features. Image 1 • The size of the VO 2 microrods has been successfully controlled by the precursor V 2 O 5 film thickness. • Temperature range for producing VO 2 microrods was found to be between 600 °C and 650 °C. • Microrods growth is aligned along two directions on the sapphire crystal surface. • Optical properties have been studied by light scattering through metal-insulator transition (MIT). • The MIT characteristics depend on the microrod size and distribution, and exhibits memory-like behavior during cooling. [ABSTRACT FROM AUTHOR]

The problem of intermediate phase in pure single PbZrO 3 crystal, appearing below the main transformation from the paraelectric to antiferroelectric state, was investigated and analysed based on changes in the birefringence, secondary ion mass spectroscopy, and x-ray photoelectron spectroscopy. Controlled changes in stoichiometry of the crystal were achieved by thermal treatment of the crystal in ultra-high vacuum and at high temperatures, thereby creating defects in all sublattices which influence the appearance of this intermediate phase. The results obtained have allowed correlating changes in the distribution of individual elements in surface and crystal volume, as well as their concentration and their electron states, with changes in the intermediate phase temperature range. • Influence of intrinsic and extrinsic crystal defects on phase transitions in PbZrO 3. • Existence of chemical inhomogeneity in surface layer of PbZrO3 single crystal. • Types and concentration of defects influence the existence of intermediate phase. [ABSTRACT FROM AUTHOR]

A typical hydrothermal preparation approach was successfully exploited and designed for the in situ growth of highly ordered Co 3 O 4 nanostructure precursors on a Ni foam substrates, a series of Co 3 O 4 nanoarray-based electrocatalysts was obtained via a subsequent calcination procedure. The formation of Co 3 O 4 hierarchical structures with different morphologies depended upon the hydrothermal time, which was used to further reveal the growth mechanism of the Co 3 O 4 nanostructures. H 2 O and CO(NH 2) 2 were selected as probe molecules to evaluate the electrocatalytic activity over the resulting Co-based electrocatalysts, and the influence of the morphology on the electrocatalytic performance was further investigated via employing different hydrothermal times. It is worth noting that Co 3 O 4 /NF-11h nanosheets@nanoneedles heterostructures with a low density of nanosheets presents superior electrocatalytic performance and long-term durability owing to an increased exposure to active sites in the hierarchical nanostructure. The Density Functional Theory (DFT) calculations results show that H 2 O molecules are preferentially adsorbed at the top of the Co 3 O 4 (111) crystal surface. This work emphasizes the significance of effective structure design for the development of robust and precious metal-free electrocatalysts via the precise control of catalyst morphology. The core–shell Co 3 O 4 NAs-11h revealing nanosheets@nanoneedles heterostructures presents the highest catalytic performance and long-term durability owing to the more exposure to active sites of the hierarchical structure. Image 1 • Co 3 O 4 is prepared by one-step hydrothermal reaction. • Co 3 O 4 /NF-11h can serve as electrocatalytic water oxidation and urea splitting catalysts. • Co 3 O 4 /NF-11h presents an excellent long-term electrochemical durability. [ABSTRACT FROM AUTHOR]