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[Display omitted] • Illustrating the interface reaction characteristics between diamond and Al. • Unveiling the underlying crystal orientation-dependent growth of Al 4 C 3 theoretically. • Clarifying the fracture mechanism of diamond/Al(Al 4 C 3) by first-principles calculation. • First-principles calculation provides theoretical basis for experimental phenomena. In this work, both first-principles calculations and experimental results revealed different interface characteristics of (111) and (100) diamond/Al interfaces. Tensile simulations were applied to examine the fracture behavior of diamond(111)/Al(111), diamond(100)/Al(111), and diamond(100)/Al 4 C 3 (003) interfaces. The results demonstrate that the work of adhesion and the tendency for Al-C bond formation are significantly greater at the diamond(100)/Al(111) compared to the the diamond(111)/Al(111) interface. The growth morphology arising from reactions between Al and various diamond crystal planes is closely linked to the distinct surface characteristics of the diamond. The diamond(100)/Al 4 C 3 (003)-C terminal interface shows the highest work of adhesion due to the synergistic effects of C–C and Al-C bonding, as well as the reconstruction of diamond C atoms. During the tensile calculations, multilayer relaxation occurred on the Al 4 C 3 (003) side for diamond(100)/Al 4 C 3 (003)-C terminal interface, with the highest ultimate tensile strength. While the Al atoms near the diamond(111)/Al(111) interface undergoing a clean, cohesive fracture at a tensile strain of 16 %, making it the weakest point prone to failure. The theoretical tensile strength of the diamond(100)/Al 4 C 3 (003)-C terminal interface is about 2.5 times that of the diamond(111)/Al(111) interface. Our work unveils the underlying crystal orientation-dependent growth of Al 4 C 3 and the fracture mechanism of diamond/Al by first-principles calculations and experiments. [ABSTRACT FROM AUTHOR]

[Display omitted] • Firstly, developed CsPbI 2 Br based PSC using fully hot air-assisted methodology. • Hot air-assisted process enabled to formation of highly quality thin films. • Achieved decent PCE of 13.74 % (1-Sun), and indoor PCE of 22.50 % (3200 K, 1000 lx). • Hot air processed PSCs showed superior thermal stability compared to hot plate. • Introduced methodology is a promising approach for scalable production of PSCs. The all-inorganic α-CsPbI 2 Br perovskite has emerged as a promising material for photovoltaic applications due to its superior optoelectronic properties and thermal stability. However, achieving a defect-free, crystalline CsPbI 2 Br perovskite film remains challenging due to the rapid crystal growth induced via high-temperature hot plate processing, which causes surface defects including pinholes and voids. This study introduces a novel hot plate-free methodology in which the perovskite film is fully processed using a dynamic hot air treatment under ambient conditions. Crystallographic and microscopic analyses reveal that hot air-assisted method produces highly crystalline, uniform, and compact perovskite film. The controlled crystal growth mechanism facilitated by the hot air process involves the formation of an intermediate phase (CsI-DMSO:PbX 2), followed by gradual solvent evaporation, resulting in improved film quality. The resulting perovskite solar cells (PSCs) exhibited a champion power conversion efficiency (PCE) of 13.74 % and maintained around 51.60 % of its initial PCE after thermal aging at 85 ℃ under ambient conditions over 1440 h. Furthermore, under indoor white LED illumination (3200 K, 1000 lx), the optimized PSC achieved an impressive PCE of 22.50 %. These findings demonstrate that the dynamic hot air process is a viable and scalable technique for producing high-performance, stable PSCs under ambient conditions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Crystallization kinetics affects the crystal morphology of α-MoO 3 nanorods. • α-MoO 3 nanorods (12 h growth) exhibit higher bactericidal performance against S. aureus and E. coli. • The crystal size and morphology determine the antimicrobial activity of α-MoO 3 nanorods. Our work evaluates the impact of crystallization rate during the synthesis of α-MoO 3 nanorods and their bactericidal performance against Gram (+) S. aureus and Gram (−) E. coli. For this purpose, α-MoO 3 nanorods were synthesized by varying the crystallization times to 12, 24, and 48 h. XRD patterns reveal that crystallization time changes crystal size. The growth of α-MoO 3 does not show chemical modifications. However, SEM and TEM reveal the characteristic nanorods morphology, where the crystallization times affect the diameter. Crystal growth also changes the atomic percentage of Mo/O, which is determined by XPS. The above was reflected in the antibacterial performance of α-MoO 3 , evaluated at different nanoparticle concentrations (0.5–4 mg/mL). The α-MoO 3 is an efficacious antibacterial for both pathogens by the enhanced crystal size, with higher bactericidal performance against Gram-positive bacteria, indicating that the rod architecture improves their interaction through electrostatic attraction with the peptidoglycan structure of S. aureus bacteria. In addition, electrochemical measurements indicate that the electroactive area of α-MoO 3 plays a key role in the nanoparticle/bacteria interaction. As a result, the intrinsic characteristics of α-MoO 3 nanorods, including crystal size, morphology, nanorod diameter, oxygen vacancies, and EASA, influence the antibacterial activity, generating materials with potential biomedical applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Surface facet engineering of ZnIn 2 S 4 was achieved via supercritical hydrothermal synthesis. • Transformation from flower-like to hexagonal plate morphology enhances NO gas sensing. • Hexagonal ZnIn 2 S 4 exhibits a significant increase in the (003)/(011) facet ratio. • Enhanced NO sensing performance due to optimized surface interaction with ZnIn 2 S 4 facets. In this study, we investigate the novel application of ZnIn 2 S 4 as an NO gas detection device by precisely modulating its surface facets through crystal growth control in a supercritical water environment. The supercritical hydrothermal synthesis successfully transforms ZnIn 2 S 4 from a flower-like structure into a hexagonal plate morphology, driven by the preferential growth of the basal plane (003) surface facet. This morphological control, which is unattainable in a subcritical environment, is evidenced by a substantial increase in the (003)/(011) facet ratio from 0.52 to 1.98 with rising temperature. NO detection results indicate that this surface morphology modification significantly accelerates sensor response, attributed to enhanced interaction between the ZnIn 2 S 4 surface and NO gas, as well as reduced diffusion limitations compared to the flower-like morphology. The hexagonal plates exhibit a remarkably fast response time of approximately 25 s, in contrast to 181 s for the flower-like counterpart. These findings underscore the crucial role of surface facet engineering in optimizing the gas-sensing properties of ZnIn 2 S 4 , highlighting its potential for advanced gas sensor applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • TS-1 membrane immobilization using oriented aggregation of nanocrystals. • A new immobilized micron-sized spherical TS-1 membrane catalyst was designed. • The compatibility of carriers with different shapes and materials was demonstrated. • The catalyst recycling was efficient and the catalytic activity remained stable. Molecular sieve membranes are widely used in separation and catalysis due to their good chemical and thermal stability, resistance to contamination, long life, and easy modification. Although immobilized molecular sieve membranes combine catalytic reactivity with recycling separation properties, preparing high-performance TS-1 molecular sieve membrane catalysts is still challenging. In this study, the oriented aggregation of nanocrystals was used in constructing molecular sieve membrane catalysts. By interfering with the crystallization of TS-1, pre-crystal modification with cetyltrimethoxysilane was employed to change the crystal growth behavior. Thus, uniform and dense molecular sieve membranes were prepared through the modulated crystallization of TS-1. This method reduced the requirements of the carrier surface properties for the loading of the membrane layer to enable the construction of membrane layers on carriers of different materials and shapes. Using this method, the effective H 2 O 2 utilization and the epichlorohydrin yield of the micron-sized spherical film catalyst prepared with the inexpensive templating agent TPABr in the chloropropene epoxidation reaction reached 95.89% and 90.22%, respectively. [ABSTRACT FROM AUTHOR]

Integrating β-Ga 2 O 3 film with varying thicknesses onto Si and GaN substrates achieves a high-performance, self-powered broadband photodetector. [Display omitted] • Developed self-powered BBPDs covering UVC to NIR using β-Ga 2 O 3 (GO) films on Si and GaN substrates. • High-temperature seed layer improved film quality, enhancing crystal growth and reducing defects. • GO/Si device achieved maximum responsivity of 10.29 A/W (266 nm) and 0.049 A/W (1064 nm) under self-powered mode. • Peak responsivity of 561 A/W (GO/Si) and 414 A/W (GO/GaN) achieved with high detectivity and low noise @5V under 266 nm. The demand for versatile applications, from ultraviolet-C (UVC) to near-infrared (NIR), has led to the need for broadband photodetectors (BBPDs). This study introduces high-performing, self-powered BBPDs by integrating gallium oxide (GO) films with varying thicknesses onto silicon (Si) and gallium nitride (GaN) substrates. The absorption coefficient shows that shorter wavelengths are absorbed near the surface while longer wavelengths penetrate deeper into the GO/Si and GO/GaN films. Under self-powered mode, the GO/Si device demonstrates maximum responsivity of 10.29 A/W, 0.031 A/W, 0.034 A/W, 0.038 A/W, and 0.049 A/W for 266 nm, 355 nm, 532 nm, 860 nm, and 1064 nm, respectively, with a fast response speed of 28/67 ms. In contrast, the GO/GaN device shows responsivity of 7.29 A/W and 0.30 A/W for 266 nm and 355 nm with a response speed of 0.75/0.95 s under 266 nm irradiation. Further, the as-fabricated GO/Si (GO/GaN) device exhibits the highest responsivity of 561 A/W (414 A/W) with high detectivity and ultralow NEP of 8.83 × 1012 Jones (4.37 × 1012 Jones) and 1.4 × 10−15 W/Hz−½ (2.96 × 10−15 W/Hz−½), respectively, at 5 V for 266 nm. The GO/Si devices perform better due to Si's smaller bandgap and higher carrier mobility, making them suitable for high-performance, self-powered broadband photodetectors and next-gen optoelectronics. [ABSTRACT FROM AUTHOR]

[Display omitted] • Propose introduction of 1,2-PDADI to the SnO 2 /perovskite interface. • 1,2-PDADI can effectively passivate oxygen vacancy defects and lead-related defects. • Modification promotes perovskite crystal growth and suppresses defect formation. • The optimized perovskite solar cell achieved a champion efficiency of 24.70 % and excellent long-term stability. SnO 2 has attracted significant attention as a potential replacement for TiO 2 in perovskite solar cells (PSCs) due to its high optical transmittance, stable physicochemical properties, and ability to process at low temperatures. However, when an SnO 2 electron-transport layer is prepared using solution gel spin coating, many oxygen vacancy defects are generated in the SnO 2 bulk and on its surface. These defects may result in nonradiative recombination at the SnO 2 /perovskite interface. This study proposes a novel and effective multibottom interfacial modification strategy that introduces 1,2-propanediamine hydroiodic acid (1,2-PDADI) molecules with multiple functional groups at the SnO 2 /perovskite interface. The incorporation of 1,2-PDADI molecules effectively passivates the oxygen vacancy defects at the SnO 2 surface and considerably improves the electronic properties of SnO 2 by reducing nonradiative recombination. Additionally, the interaction between the –NH 3 group in 1,2-PDADI and PbI 2 substantially reduces the PbI 2 content, thereby inhibiting defects forming in perovskite films. As a result, PSCs modified with 1,2-PDADI achieve a higher efficiency of 24.70% and demonstrate reduced hysteresis characteristics compared to the control (22.86 %). Thus, this study offers a cost-effective, straightforward, and effective approach for realizing high-efficiency PSCs. [ABSTRACT FROM AUTHOR]

[Display omitted] • In situ growth of an LDH/ZIF-8 hybrid coating on the MAO film surface of LA93 alloy by a one-step method. • The formation of ZIF-8 efficiently seals the intergranular defects in LDH, enhancing the stability of the film and increasing the tortuosity of the diffusion paths for corrosive agents. • LDH/ZIF-8 film effectively seals defects in the MAO film and constructs a robust physical barrier, significantly enhancing the protective capacity of the film. An in-situ grown LDH/ZIF-8 hybrid film on the surface of MAO film based on the LA93 alloy was successfully fabricated by the one-step method. The composite film, called as MLZ, demonstrates exceptional corrosion resistance. The corrosion current density is reduced by two orders of magnitude compared to the MAO film. Furthermore, it possesses significant long-term protective capabilities. Experimental measurement and density functional theory (DFT) calculations were conducted to investigate the formation mechanism of MLZ composite film. During the hydrothermal, Zn ions from the in-situ generated LDH on the MAO surface serves as active nucleation sites, facilitating the nucleation and growth of ZIF-8 crystals. The formation of ZIF-8 effectively compensates for the intergranular defects in LDH, enhancing the integrity of the film. LDH/ZIF-8 film effectively seals defects in the MAO film and constructs a robust physical barrier, significantly enhancing the protective capacity of the film. [ABSTRACT FROM AUTHOR]

We report a one-step fabrication method for large-area single-crystal organic thin films guided through vertically confined lateral crystal growth via capillary force lithography (VC-LCG via CLF). In this method, organic molecules in ink solutions self-assemble and crystallize within the vertically confined channels of patterned molds. Vertical confinement, determined by the channel depth, played a major role with regard to the crystallization and formation of single-crystalline organic thin films. We also demonstrated its usefulness by fabricating wafer-scale arrays of single-crystal organic thin film transistors with high performance and uniformly distributed electrical properties, which could be attributed to their large-scale single-crystalline nature, homogeneous film morphologies and the suppression of multiple crystal orientations. Especially, the versatility to various organic molecules, ease of processing optimization, and uniform crystallinity all over the patterned area increase the possibility of VC-LCG to apply in the industrial process. Unlabelled Image • One-step fabrication method for large-area single-crystal organic thin films guided through VC-LCG via CLF was developed. • Self-assembly of organic molecules within shallow channel depth is crucial for the formation of single-crystalline organic films. • The crystalline nature of resulting homogenous films was carefully characterized by 2D XRD, out-of-plane XRD, and SEAD. • The versatility of the technique was demonstrated by using three different ink solution of TIPS-PEN, C8-BTBT, and P3HT. • Wafer-scale arrays of single-crystal OTFTs exhibited high performance and uniform electrical properties over large area. [ABSTRACT FROM AUTHOR]

Sb 2 S 3 /perylene diimide derivatives composite micro-spheres composed of slight dendrites were synthesized by solvothermal reaction. Perylene diimide derivative with two carboxyl groups at amine position as morphology-controlling reagent is the key factor for determining the microscopic morphology of Sb 2 S 3 in this system. Time-dependent experiments have been conducted to track the formation of Sb 2 S 3 micro-spheres. Moreover, the composite material showed an excellent sensitivity of 29.8 μA mM−1 cm2 with a low detection limit of 50 pM, it also showed better stability and selectivity in hydrazine detection. This approach not only regulate the morphology and composition of Sb 2 S 3 submicron materials effectively, but also provide new ideas for the manufacture of metal sulfide- perylenediimide amino acid derivative materials, which will be suitable for sensing, catalysis, and photovoltaic applications. Rod-like Sb 2 S 3 crystal converted to microspheres composed of dendrites by using perylenediimide derivative as crystal directing agent. Due to the synergetic effect through rationally assembling of different materials, the product shown excellent sensing performance toward hydrazine. Unlabelled Image • Perylene diimide amino acid derivative used as crystal growth directing agent to convert the original rod-shaped Sb 2 S 3 into microsphere composed of dendritic crystals. • The modified Sb 2 S 3 crystal exhibited excellent electrochemical detection performance for hydrazine. [ABSTRACT FROM AUTHOR]

There is a great need for depositing SnO 2 film onto micro/nano-structures in various fields. However, the growth of SnO 2 on micro/nano-structures by atomic layer deposition (ALD) using tetrakis(dimethylamido)tin and water needs to be further investigated. In this work, ultrathin SnO 2 were deposited uniformly and conformally on carbon nanotubes (CNTs) by ALD. The effects of deposition temperature on ALD-growth and the effect of film thickness on crystallographic state were investigated in detail. There is exceptionally high deposition rate at low deposition temperature. SnO 2 tends to be deposited on the surface layer of CNTs substrate with CVD-like manner below 165 °C, but it can be deposited uniformly on each CNT mainly by chemical adsorption at high deposition temperature. In addition, the crystallographic state of SnO 2 can also be controlled by regulating the film thickness. Using this feature, the electrochemical performances of SnO 2 @CNT composites with various thicknesses as the anode materials for lithium ion batteries (LIBs) were studied. The enhanced cycling stability and rate capability of SnO 2 @CNT could be attributed to small SnO 2 thickness and limited crystal growth in ultrathin SnO 2 , which can overcome electrode degradation and enhance the lithium ion diffusion coefficient and electron kinetics of electrode. Unlabelled Image • Ultrathin SnO 2 can be deposited uniformly and conformally on carbon nanotubes by atomic layer deposition using tetrakis(dimethylamido)tin and water. • The crystallization of SnO 2 /CNTs can be controlled by regulating the number of ALD cycles. • The limited crystallization and small SnO 2 thickness can enhance the cycling performance and rate capability of the SnO 2 @CNTs composite as the anode for Lithium ion battery. [ABSTRACT FROM AUTHOR]

The stability of the Nitrogen-polar (000-1) surface of single-crystal bulk GaN substrates is studied for layers grown by plasma-assisted molecular beam epitaxy (PAMBE) in Nitrogen-rich conditions at 730 °C. It is shown that smooth GaN layers with parallel atomic steps are obtained for substrates when the surface crystal miscut angle is larger than 2o, revealing a highly stable epitaxial growth regime on single crystals. A step meandering pattern is observed on layers grown on lower miscut angle substrates. The meandering periodicity is found to have an inverse dependence on growth rate and miscut angle. This is opposite to what is observed for epitaxy on the Ga-polar surface. Combining analytic modeling and kinetic Monte Carlo simulations, it is shown that the existence of an Ehrlich-Schwoebel Barrier (ESB) in the PAMBE growth of GaN in nitrogen-rich conditions on (000-1) GaN reproduces the experimentally observed periodicity of step meandering. Assuming that ESB height depends on interactions between diffusing adatoms, all experimental phenomena are reproduced. • Nitrogen-rich growth of high quality GaN layers in plasma-assisted MBE • High miscut angle bulk N-polar GaN substrates used to obtain atomically smooth layers • Meandering steps with periodicity increasing with increasing inter step distance • kMC simulations reproduce experimental results assuming Ehrlich-Schwoebel barrier dependent on the adatom concentration [ABSTRACT FROM AUTHOR]

Single crystal pseudo-wurtzite ZnSnN 2 films were grown successful for the first time with [ 11 2 ¯ 0 ] growth direction. The ZnSnN 2 films were grown as single crystal on sapphire substrate using ZnO buffers. There was no formation of an orthorhombic structure detected in all the samples. The epitaxy relationship found in the grown single crystal ZnSnN 2 films was: [ 1 1 ¯ 00 ] ZnSnN 2 //[ 1 1 ¯ 00 ] ZnO//[ 10 1 ¯ 0 ] Al 2 O 3 and [0001] ZnSnN 2 //[0001] ZnO//[ 1 1 ¯ 0 1] Al 2 O 3. By changing the films' composition, the optical bandgap of the single crystal wurtzite ZnSnN 2 films were tuned from 1.6 to 2.0 eV. The densities and mobilities of the grown ZnSnN 2 films were investigated and compared. The successful growth of non-polar ZnSnN 2 films on commercial sapphire substrate will promote study in this material and related device fabrication. Unlabelled Image • First report of successful growth of (11 2 ¯ 0) single crystal ZnSnN 2 films • Determine the epitaxial relationship between (11 2 ¯ 0) ZnSnN 2 , (11 2 ¯ 0) ZnO and 1 1 ¯ 02 Al 2 O 3 • Optical bandgap of single crystal wurtzite ZnSnN 2 films were tuned from 1.65 to 2.0 eV. • Employing ZnO buffer is a simple process which is applicable to growth nonpolar ZnSnN 2 films on various substrates' surface. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Conformal growth of an amorphous Al 2 O 3 layer covering 2D Ag NPs–arrays is shown. • Nanodomes with tapered shape that mimic the 2D NPs-arrays topography are observed. • Tapered shape relates to angular dependence of deposition rate and self-sputtering. • a-Al 2 O 3 cover modifies the reflectance and SPR modes of 2D NPs-arrays. Abstract We demonstrate successful nanometric conformal coverage by pulsed laser deposition (PLD) of Ag nanoparticle (NP) arrays with a transparent amorphous Al 2 O 3 layer. The Ag NPs-arrays are formed by a bimodal distribution of well separated spheroidal Ag NPs with an average in-plane diameter of 40 or 90 nm and a maximum height of ∼70 nm. The cover layer induces no relevant alteration of the morphology and organization of the underlying Ag NPs-arrays. The conformal nature of the Al 2 O 3 cover layer is confirmed by its surface topography that shows the presence of characteristic nanodomes, with sizes determined by those of the underlying Ag NPs. The distinctive tapered shape of the nanodomes is related to the angular dependence with respect to the NPs surface normal of the deposition rate and the self-sputtering induced by energetic Al+ ions present in the laser generated plasma. The presence of the amorphous Al 2 O 3 cover layer red-shifts the characteristic dipolar and quadrupolar Surface Plasmon Resonances of Ag NPs and increases the total and diffuse reflectance of the NPs arrays. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights: • Growth of single crystal thick (30 nm) Ag(1 1 1) films on Si(1 1 1) 7 × 7 at room temperature. • Initial linear evolution of surface coverage by Ag islands with amount of Ag deposited. • Average size of Ag terrace widths 5–6 nm; terrace heights 2–3 monolayers. • Low surface barrier height on strongly n-doped Si(1 1 1): 0.4 eV. Abstract Growth of Ag films of up to 30 nm thickness on Si(1 1 1) 7 × 7 at room temperature is investigated by low energy electron diffraction (LEED), X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM). LEED revealed the coexistence of Ag and Si spots starting with 1 monolayer (ML) of Ag deposited. The Ag lattice constant, starting with 25 ML, is slightly higher than for bulk Ag and increase linearly with Ag thickness, reaching about 4.2 nm for the thickest films. The average terrace widths detected from LEED spot profile analysis are about 30 nm for clean Si(1 1 1) 7 × 7 and about 5.5 nm for the thickest Ag(1 1 1) film, in agreement with STM observations. The intensity variation of core levels analyzed by XPS is taken into account by a model assuming the initial formation of Ag islands with linear variation of coverage vs. the amount of Ag deposited, followed by growth in a quasi layer-by-layer mode. The interface barrier is in the range of 0.4 eV, lower than all values reported previously. Ag deposited on Si(1 1 1) 7 × 7 at room temperature provides flat Ag(1 1 1) for synthesis of 2D materials, and may be used for low barrier Schottky diodes. [ABSTRACT FROM AUTHOR]

Highlights • NiAl-layered double hydroxides are grown on Si substrate by hydrothermal method. • Growth mechanism of the NiAl-layered double hydroxides is investigated. • Band gap energy of the NiAl-layered double hydroxide is found to be 4.15 eV. Abstract We report on the growth mechanism of NiAl-based layered nanostructures on rigid substrates using a low-temperature hydrothermal method. NiAl-layered double hydroxide (LDH) structures were grown with various source concentrations and growth times. Structural and optical investigations showed that uniform NiAl-LDHs were grown on the substrates because Al(OH) 3 was sufficiently supplied from the aluminum thin film seed layer when the Ni source concentration was low and in the initial stage of the growth. However, a bilayer of NiAl-LDH and α-Ni(OH) 2 was formed when the Ni sources were sufficiently supplied and the growth time was long enough because of the deficient Al(OH) 3 sources at the growth front. [ABSTRACT FROM AUTHOR]

Highlights • c-axis (0 0 1) oriented Bi 2 Se 3 thin films can be grown by PLD under a high ultra-pure Ar pressure on (0 0 1)-oriented SrTiO3 substrates, with no trace of secondary phases or other crystallographic orientation. • In-situ STM experiments show that surface roughness of Bi 2 Se 3 thin films grown on STO substrates does not sizebly increase (i.e. RMS is about 0.5 nm and 0.7 nm for films grown on Al 2 O 3 and SrTiO 3 , respectively); however, clear step-terraces with a 1 quintuple-layer height are no longer visible in case of SrTiO 3. • ARPES data show a single Dirac cone with a well-defined texture of the topological surface states, fully comparable to what observed in thin films and single-crystals. Such results, showing the very intrinsic electron properties of the as grown material, open perspectives in the development of devices based on multi-layered heterostructures including the topological insulator Bi 2 Se 3 and the family of oxide perovskites. Abstract We report on the reproducible surface topological electron states in Bi 2 Se 3 topological insulator thin films when epitaxially grown by Pulsed Laser Deposition (PLD) on (0 0 1)-oriented SrTiO 3 (STO) perovskite substrates. Bi 2 Se 3 has been reproducibly grown with single (0 0 1)-orientation and low surface roughness as controlled by ex-situ X-ray diffraction and in situ scanning tunnel microscopy and low-energy electron diffraction. Finally, in situ synchrotron radiation angle-resolved photo-emission spectroscopy measurements show a single Dirac cone and Dirac point at E B ∼ 0.38 eV located in the center of the Brillouin zone likewise found from exfoliated single-crystals. These results demonstrate that the topological surface electron properties of PLD-grown Bi 2 Se 3 thin films grown on (0 0 1)-oriented STO substrates open new perspectives for applications of multi-layered materials based on oxide perovskites. [ABSTRACT FROM AUTHOR]

Highlights • Nano-structured ZnO films were grown on c-plane sapphire substrates using PLD. • Crystalline properties and morphology of the films were studied by XRD and SEM. • Various film nanostructures were obtained depending on growth conditions. • The surface and volume structure of the films were found to be correlated. • Growth at 825 °C and a pressure of 10 mTorr lead to nearly epitaxial ZnO films. Abstract In this work, we report on the synthesis of highly textured c-oriented zinc oxide (ZnO) thin films on single crystal c-plane sapphire substrates using pulsed laser deposition (PLD). The growth experiments were performed at different substrate temperatures and oxygen pressures. The crystalline properties and surface morphology of the resulting films were studied using XRD peak analysis, rocking curve measurements, and SEM imaging. By varying deposition pressure and temperature, we observe different surface morphologies of the ZnO thin films, from smooth surfaces to clusters of grains and nanorods. The surface and volume structure of the films were found to be correlated. Within the range of experimental parameters used in this work, a growth temperature of 825 °C and a pressure of 10 mTorr lead to nearly epitaxial ZnO thin films having the largest grain size and the lowest strain perpendicular to the substrate surface i.e. along the growth axis. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • ZIF-8 films were grown for the first time on CVD deposited amorphous Si layers. • The role of solvents and surface chemistry on the growth process was studied. • The silanol density and the Lewis basic strength of the surfaces affect the relevant reaction steps. • Experimental results were validated by the DFT modelling of the proton exchange. Abstract Thin amorphous silicon films, deposited at low temperature by Inductively Coupled Plasma Chemical Vapor Deposition, have, for the first time, been employed as substrate for ZIF-8 growth. In order to investigate the role of the surface chemistry on the nucleation process, films have also been grown on other silicon-based substrates such as H-terminated Si(1 0 0), SiO 2 and quartz. Film preparation was carried out at room temperature using a mixed Zn nitrate and imidazole solution in methanol or ethanol. Using methanol, continuous ZIF-8 films were obtained on amorphous Si and H-terminated Si(1 0 0), while less homogeneous films were formed on the other surfaces. In ethanol, slower growth rates occurred and thinner films, compared to the ones in methanol, were obtained. These slower rates highlight the different effects of the four surfaces on the growth process. These differences have been related to the silanol density of the surfaces and to the Lewis basic strength which affect imidazole moiety deprotonation. H-terminated Si(1 0 0) and amorphous Si turned out to be the most reactive surfaces, whereas on quartz and, especially, on SiO 2 reactivity was much lower. Experimental results have been validated by the DFT modelling of the proton exchange, which takes place between the imidazole group and the surface. Finally, the VOCs adsorption capability of ZIF-8 films grown on amorphous silicon has been evaluated through temperature desorption experiments. [ABSTRACT FROM AUTHOR]

[Display omitted] • Super-flat and uni-oriented cobalt film achieved via one-step electrodeposition using benzenesulfinic acid (BNS). • The highly electron-donating sulfite group in BNS enhances adsorption and cathodic polarization. • Progressive nucleation with BNS leads to a more uniform and compact cobalt film morphology. • Selective adsorption of BNS on cobalt planes promotes preferential orientation of (0 0 2) crystal plane growth. • Obvious crystal growth of the film is observed after annealing, leading to a desired electrical property. A precise control of the microstructure of electrodeposited cobalt film is crucial for attaining the desired and reproducible electrical performance in edge nanoelectronic devices. Here we realize the super-flat and uni-oriented cobalt film through a one-step electrodeposition process using benzenesulfinic acid (BNS) as additive. We find that the unsaturated sulfite group in BNS plays a key role in the super-flat cobalt electroplating. Molecular activity analysis and electrochemical test results suggested that the electron donating ability of the sulfite group was higher than that of the sulfonate group, resulting in stronger adsorption of BNS on the cobalt surface and enhanced cathodic polarization. Nucleation model fitting and surface morphology evolution studies revealed that the cobalt nucleation with BNS shifted to progressive nucleation from instantaneous nucleation in the additive-free electrolyte, leading to a more uniform and compact film morphology. Furthermore, equilibrium adsorption calculations indicated that the selective and strong adsorption of BNS on cobalt planes was responsible for the preferential orientation of the (0 0 2) crystal plane growth. After annealing, cobalt films prepared with BNS exhibited substantial grain growth and impurity diffusion, which further improved the electrical performance. [ABSTRACT FROM AUTHOR]

Graphical abstract Steric hindrance of diethylzinc adsorption disappears at 150–200 °C. Highlights • Governing factors of growth per cycle (gpc) were identified depending on growth temperature. • The saturated gpc values at T < 150 °C are governed by steric hindrance. • Above 200 °C, the saturated gpc values are decided by surface hydroxyl concentration. • Effective activation energy of the DEZ adsorption was found to be ∼8.50 kJ/mol. Abstract We present a kinetic model for the reaction of diethylzinc (DEZ) adsorption in atomic layer deposition (ALD) of ZnO from DEZ and water. The proposed model has been verified by comparing kinetic experimental data to the prediction of the model in the temperature range of 60–200 °C. In this model, DEZ molecules are molecularly adsorbed on the hydroxyl-terminated surface in the first elementary reaction. Then the molecularly-adsorbed DEZs either desorb from the surface, or undergo an irreversible ligand exchange reaction and form monoethylzinc (MEZ)-terminated surface by liberating ethane molecules. According to the integrated rate law of the model, as the exposure time of DEZ increases, the growth per cycle (gpc) of ALD, i.e., the thickness increment per cycle, rapidly increases and then saturates showing the self-limiting growth behavior. The required DEZ exposure time to reach the saturated gpc value is shortened when the chemical equilibrium between the molecular adsorption and desorption shifts toward the adsorption, as this leads to higher effective rate constant in the overall mechanism of the DEZ adsorption. Although the saturated gpc value is primarily governed by the hydroxyl concentration on the ZnO surface, it is also heavily influenced by the steric hindrance due to the bulkiness of the ethyl ligands. We have determined that the critical temperature at which the steric hindrance disappears is around 150–200 °C, by investigating the variation of the hydroxyl concentration with temperature. At temperatures lower than 150 °C, we have observed that the saturated gpc value is governed by the steric hindrance rather than the hydroxyl concentration. However, the saturated gpc value at 200 °C has been achieved purely by the hydroxyl concentration. In other words, all hydroxyl groups at 200 °C have been consumed and saturated by the MEZ molecules of which the steric hindrance-free concentration has been evaluated to be ∼7.1 /nm2. In addition, the effective activation energy was estimated to be ∼8.50 kJ/mol by using the effective rate constants of all temperatures investigated. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Cr 3 C 2 -VC/Co-based cladding layers was fabricated by laser cladding. • Plastic deformation and carbides/cobalt interfaces were characterized and evaluated by HAADF-EDS, EBSD and HRTEM. • The agglomeration of a substructure of nanostructured powders was found to influence the carbide growth strongly. Abstract Cladding layers were prepared on carbon steel using nanostructured carbide-strengthened cobalt (Co)-based alloy (using nanostructured tungsten carbide as hard phases) as a deposited material by multi-track laser cladding. In addition to Co-based alloy, the deposited materials contained nanostructured chromium carbide (Cr 3 C 2), vanadium carbide (VC), or Cr 3 C 2 and VC. Compared with the substrate, all cladding layers had an improved oxidation resistance with an increased time (0–50 h) at 800 °C. Cr 2 C 3 had a higher oxidation-resistance performance than VC and the mutual reaction of Cr 2 C 3 and VC. The constitution and phases of the cladding layers indicated hexagonal-close-packed-α and body-centered-cubic-β cobalt and hard carbides, such as CoC x , V 8 C 7 , and Cr 3 C 2 , and some decarburization as Co 3 W 3 C and WC 1-x. Elemental inter-diffusion occurred between the different phases as indicated by transmission electron microscopy and electron backscattered diffraction. Mixed carbide has a larger misorientation than the cobalt matrix, and electron backscattered diffraction has considerable potential to evaluate plastic deformation. The average grain size of the hard carbides was much larger than that of the original deposited material. The carbides grew rapidly through interfacial diffusion, boundary migration, and coalescence, which followed the Kirkendall effect and Ostwald-coarsening mechanism. This research helps to understanding the microstructure, oxidation resistance, grain growth, and interfacial behavior in multi-track laser-cladding layers. [ABSTRACT FROM AUTHOR]

Graphical abstract Few layer 2D MoS 2 vertical grown on biomass-based hollow carbon fibers showed excellent lithium and sodium storage performance. Highlights • Porous, hollow, individual carbon fibers are prepared by processing the palm silk. • Fewer layer 2D MoS 2 are vertically grown on BHCFs via a facile hydrothermal method. • The MoS 2 @BHCF electrodes display excellent lithium and sodium storage performance. • DFT calculations verify an optimized structure of MoS 2 vertically grown on BHCF. • A lower energy barrier of Li diffusing through MoS 2 crystals than Na is testified. Abstract 2D MoS 2 sheets have been extensively served as the anode materials for lithium and sodium ion batteries (LIBs, SIBs) due to its high theoretical capacity. However, its low electrical conductivity and large volume change during cycles impair the rate performance and lifespan of the electrodes. Herein, few layer MoS 2 nanosheets vertically grown on biomass-based hollow carbon fibers (BHCFs) derived from palm silk are prepared via a facile hydrothermal method. The density functional theory (DFT) calculations verify an optimized structure of MoS 2 vertically grown on BHCF surface and the strong interaction between the S edges of MoS 2 and the carbon surface. The few layer nanosheets structure and the enhanced conductivity of MoS 2 by biomass derived hollow BHCF ameliorate the diffusion of both Li and Na ions and electrons, as well as the electrode reaction kinetics. Deservedly, the MoS 2 @BHCF electrodes display excellent lithium and sodium storage performance, especially remarkable high-rate capabilities in LIBs. The higher reversible capacity in LIBs than in SIBs reflects the better kinetics of MoS 2 @BHCF in LIBs, owing to a much lower energy barrier of Li atoms diffusing through MoS 2 crystals than the Na counterparts. [ABSTRACT FROM AUTHOR]

Highlights • Co, Mn-LDH nanoneedle arrays grown on Ni foam with strong adhesion is fabricated. • The unique structure had good conductivity, and relieved volume change. • It exhibits large specific capacitance, superior rate capability and cyclability. Abstract To solve the agglomeration of layered double hydroxides (LDH) for improving their supercapacitor performances, Co, Mn-LDH nanoneedle arrays grown on Ni foam (Co, Mn-LDH@NF hybrid) was fabricated via a one-step hydrothermal strategy. The Ni foam served as the skeleton frame for anchoring Co, Mn-LDH nanoneedles to form three dimensional net structures, and open spaces among Co, Mn-LDH nanoneedles. When Co, Mn-LDH@NF hybrid was used as binder-free electrodes for supercapacitors, it displayed outstanding supercapacitor performances with a high specific capacitance of 2422 F g−1 at 1 A g−1, and superior cyclic stability for maintaining a capacitance of 2096 F g−1 after 3000 cycles, which was only 13.5% capacity loss ratio. The excellent supercapacitor performances were ascribed to three dimensional net structure and LDH nanoneedle structure, which provided abundant electrochemical active sites, alleviated volume expansion, and had good electrical conductivity. [ABSTRACT FROM AUTHOR]

Highlights • Ferromagnetic patterns can be written into paramagnetic Fe 78 Ni 22 thin films by FIB. • So far this system was possible to grow only on copper single crystal. • We show that it is possible to use also silicon wafer as a substrate. • Wet etching and UHV processes for sample preparation are shown and discussed. • Writing of magnetic patterns by FIB is demonstrated. Abstract We have studied the growth of metastable face-centered-cubic, non-magnetic Fe 78 Ni 22 thin films on silicon substrates. These films undergo a magnetic (paramagnetic to ferromagnetic) and structural (fcc to bcc) phase transformation upon ion beam irradiation and thus can serve as a material for direct writing of magnetic nanostructures by the focused ion beam. So far, these films were prepared only on single-crystal Cu(1 0 0) substrates. We show that transformable Fe 78 Ni 22 thin films can also be prepared on a hydrogen-terminated Si(1 0 0) with a 130-nm-thick Cu(1 0 0) buffer layer. The H-Si(1 0 0) substrates can be prepared by hydrofluoric acid etching or by annealing at 1200 °C followed by adsorption of atomic hydrogen. The Cu(1 0 0) buffer layer and Fe 78 Ni 22 fcc metastable thin film were deposited by thermal evaporation in ultra-high vacuum. The films were consequently transformed in-situ by 4 keV Ar+ ion irradiation and ex-situ by a 30 keV Ga+ focused ion beam, and their magnetic properties were studied by magneto-optical Kerr effect magnetometry. The substitution of expensive copper single crystal substrate by standard silicon wafers dramatically expands application possibilities of metastable paramagnetic thin films for focused-ion-beam direct magnetic patterning. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Edge enriched Au-NPs patterns were fabricated by using agarose stamps. • HNO 2 modified surfaces show high affinity to Au-NPs. • A "cylindrical droplet" model, analogous to "coffee-ring" effect, was proposed. • Au-NPs patterns serve as templates for the growth of ZnO-NRs patterns. Abstract Amino functionalized surfaces were selectively modified via the combination of a wet agarose stamping technique and microcontact printing technique. Because of the specific reaction environments and diffusion of HNO 2 confined in agarose stamp, the reaction of amino groups in the edge of the strip pattern was much more intense than other areas. The modified amino groups in the edge areas show higher affinity to Au-NPs than other areas, consequently, edge enriched Au-NPs patterns were observed after the self-assembly of Au-NPs. A "cylindrical droplet" model, in a manner analogous to "coffee-ring" effect, was proposed to describe the diffusion of HNO 2 from the bulk to the edge in agarose stamp. By using such density varied Au-NPs patterns as templates for the growth of ZnO nanorods, we observed high density of Au-NPs resulting in high density and highly (0 0 1) oriented ZnO nanorods. In contrast, sparse and non-oriented ZnO nanorods were grew on low density of Au-NPs areas. Our findings might open new routes for the fabrication of gradient patterns and extend applications of Au-NPs patterns in surface enhanced Raman scattering and catalysis. [ABSTRACT FROM AUTHOR]

Highlights • Molecular dynamics simulations studied the stress generation during thin film growth. • A larger tensile stress occurs with a larger contact area between adjacent islands. • The width of the grain boundary region narrowed upon ceasing deposition. • The inverse relationship between grain size and stress breaks at a critical size. • The deposited roughness changed depending on the texture of the film. Abstract Molecular Dynamics (MD) simulations have been employed to model the growth stresses of body-centered cubic (BCC) metal thin films, with tungsten being the primary case study, as a function of various embryonic island textures, grain sizes, grain morphologies, deposition rates, and deposition energies. Depending on the shape and size of the islands, the tensile stress varied as a function of the available contact area. If the adatoms were sufficiently confined to the surface, the tops of these islands initiated the elastic strain for coalescence. This was particularly relevant for island morphologies that had varied curvature gradients near the contact points. Depending on the texture of the film, the roughness changed, with the 〈1 1 1〉 orientation being the roughest and 〈0 0 1〉 orientation being the smoothest. These topologies are explained by differences in surface diffusivities. The injection energy of adatoms was found to have a dramatic effect on film stress. Species with injection energies in excess of 50 eV resulted in a notable increase in the structural disorder at the grain boundary-free surface intersection which corresponded to a reduction of the tensile stress. Upon ceasing deposition, these disordered regions experienced a recovery to the BCC structure with an increase in the tensile stress. Upon resuming deposition, at the same energies, the disordered structure re-developed and the stress became less tensile and matched the prior deposited stress evolution. Finally, reducing the grain size resulted in an increase in tensile stress up to a critical size, whereupon it decreased. This reversion is explained in terms of grain growth and grain boundary structure during deposition. Through these series of systemically controlled MD simulations, the paper addresses the significance of different microstructures on the evolution of thin film stress. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Simulation of carbide layer growth during carburizing and annealing tantalum. • Effect of annealing on carburized tantalum. • Obtaining different surface microstructures: TaC, Ta 2 C or Ta(C) + Ta 2 C. Abstract This paper describes a model developed to simulate the evolution of carbide layers (TaC/Ta 2 C) formed during carburizing and annealing treatments of tantalum. The model is based on a parabolic evolution of the layer thickness during the growth, and on the carbon conservation during the annealing. In order to validate this model a MATLAB® program was developed. It enables the prediction of the evolution of the tantalum carbide layers (nature and thickness) for a desired treatment defined by a temperature, a carburizing and an annealing duration. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Micro-Raman investigation of graphene on Si/SiO 2 substrate. • Optical properties of CVD graphene in a broad energy range using ellipsometry. • Discussion on the unintentional doping of the sample. Abstract Despite intensive investigations in the UV (ultraviolet) and visible range, the research on the optical properties of graphene in the extended near and mid infrared range by means of Spectroscopic Ellipsometry (SE) remains limited yet. Herein, the optical properties of a Chemical Vapor Deposition (CVD)-grown monolayer graphene, transferred from a copper substrate onto SiO 2 /Si, were studied in the broad energy range (0.38–6.2 eV) using Variable Angle Spectroscopic Ellipsometry (VASE). The morphological and the structural properties of the samples were investigated by Micro-Raman Spectroscopy, Wavelength Dispersive X-ray (WDX) analysis, Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). The Lorentz oscillator model proposed for the optical response of graphene fits very well the experimental data. An unintentional doping, revealed by Micro-Raman Spectroscopy and WDX, is reported. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Vertically aligned MoS 2 nanosheets on the surface of mesoporous In 2 O 3 nanocubes. • The interfacial transfer of electrons from In 2 O 3 to MoS 2 nanosheets. • Highly exposed edge sites of the MoS 2 to enhanced gas sensing properties of the sensor. • The sensor revealed excellent response to NO x at room temperature. Abstract The coupling of MoS 2 with In 2 O 3 is a well-known challenge due to the lower stability of MoS 2 in the presence of oxygen at high temperature. In the present work, stable mesoporous MoS 2 @In 2 O 3 composites were designed by a sonochemical reaction and a low temperature hydrothermal method, in which MoS 2 nanosheets (NSs) were vertically planted on highly mesoporous In 2 O 3 nanocubes. The mesoporous MoS 2 @In 2 O 3 -II nanocomposite with a MoS 2 and In 2 O 3 mass ratio of 1:1 exhibited a high response of 10.3–100 ppm NO x , and ultrafast response time of 1–9 s from 100 to 0.1 ppm. The enhance gas response of MoS 2 @In 2 O 3 -II reveals the synergistic effect of the interfacial transfer of electrons from In 2 O 3 nanocubes to MoS 2 NSs, and the highly exposed active edges of vertically aligned MoS 2 NSs. The MoS 2 @In 2 O 3 -II sensor is a promising candidate as a gas sensing material due to its excellent structure and outstanding properties at room temperature (RT). [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Au islands were grown on the positively polarized surface of PbTiO 3 nanoplates. • Heterostructured Au@PbTiO 3 nanoplates demonstrated a superior UV-light activity. • Ferroelectric polarization is favorable for the separation of photoinduced carriers. Abstract In this work, heterostructured Au@PbTiO 3 nanoplates were synthesized successfully via a simple hydrothermal process. It is revealed that Au islands with the size of 8–20 nm selectively deposited on the positively polarized surface of the single-crystal and single-domain PbTiO 3 nonaplates. The composite demonstrates an efficient photocatalytic performance toward degradation of Rhodamine B (RhB) solution under UV light. The possible mechanism is that the ferroelectric polarization efficiently separates the photogenerated electrons and holes and reduces the recombination of them. Then, the ferroelectric polarization field urged the electrons concentrated on the positively polarized surface and then transformed oxygen into superoxide radicals to enhance the photocatalytic activity. Recycled activity tests show that the heterostructured Au@PbTiO 3 nanoplates would inhibit the photocorrosion behavior and provide high stability. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • CoFe 2 O 4 films deposited by PLD with various laser repetition rates of 2–10 Hz. • A magnetic anisotropy switching in the films with change in pulse repetition rates. • Changing in surface morphology of films causes a different magnetic properties. • K u < 0 for 2 and 3 Hz and K u > 0 for 5, 7 and 10 Hz deposited films. • Change in the K u sign lead to change of an easy axis from in-plane to out-of-plane. Abstract In this paper, we report a switch of magnetic anisotropy in CoFe 2 O 4 (CFO) films induced by change in laser pulse repetition rate. CFO films were deposited on MgO (0 0 1) substrates using pulsed laser deposition method with 2, 3, 5, 7 and 10 Hz laser pulse repetition rates. Atomic force microscopy images exhibited the film surface aggregation tends to compact shape with large size islands on the surface of the samples deposited by 2 and 3 Hz while the size of islands decreased on the surface of the 5, 7 and 10 Hz CFO films. The hysteresis curve of films indicated magnetic anisotropy and switching of the easy axis direction by changing laser repetition rates. The films grown at 2 and 3 Hz exhibit an in-plane easy axis, while by increasing the laser repetition rate, the easy axis switches to out-of-plane. The Raman spectra showed the rearrangement of Fe3+ and Co2+ cations on octahedral and tetrahedral sites in the structure by changing the laser pulse repetition rate. Change in the strain, morphology evolution and cation distribution are responsible for the change in easy axis direction and existence of shrinking at M–H loops. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • SLG on SiC is mainly composed by large ML graphene terraces with small BL islands. • QFSMG on SiC is mostly formed by extensive ML graphene terraces. • Terraces in QFSMG are not uniform due to inhomogeneous H intercalation. • Border areas as steps, stripes and bands are formed by BL or TL graphene. Abstract We report on a comparative structural characterization of two types of high quality epitaxial graphene layers grown by CVD on 4H-SiC(0001). The layers under study are a single layer graphene on top of a buffer layer and a quasi-free-standing graphene obtained by intercalation of hydrogen underneath the buffer layer. We determine the morphology and structure of both layers by different complementary in-situ and ex-situ surface techniques. We found the existence of large islands in both samples but with different size distribution. Photoemission electron microscopy (PEEM) measurements were performed to get information about the chemical environment of the different regions. The study reveals that monolayer graphene prevails in most of the surface terraces, while a bilayer and trilayer graphene presence is observed at the steps, stripes along steps and islands. [ABSTRACT FROM AUTHOR]

Highlights • Silicon has been grown on the β-Si 3 N 4 (0 0 0 1)/Si(1 1 1) interface. • Due to a Volmer-Weber growth mode, silicon nanoclusters form. • Synchrotron based core-level photoemission spectroscopy and scanning tunneling microscopy measurements have been carried out. • The combination of the two techniques has allowed us to assign all components of the Si2p and N1s core level spectra. • The interface is discussed in the light of possible applications. Abstract Silicon has been grown on the (8 × 8)–reconstructed β -Si 3 N 4 (0 0 0 1) surface at 350 °C temperature. The pure Volmer-Weber growth mode has induced the formation of nano-sized silicon clusters randomly distributed on the surface. Synchrotron radiation photoelectron spectroscopy and scanning tunneling microscopy have been employed to study the system. A fit to the photoemission spectra, complemented by topographic information, has allowed us to assign each Si2p and N1s component to the different non equivalent sites of silicon and nitrogen atoms. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Pure ZnO and Pd-doped ZnO nanorod arrays were in-situ grown on the ceramic tube via a simple wet-chemical route. • Pd-doped ZnO nanorod sensor exhibited improved TMA sensing properties compared to pure ZnO nanorod sensor. • The enhanced sensing mechanism of Pd-doped ZnO nanorods was discussed. Abstract Pure ZnO and Pd-ZnO nanorod arrays were in-situ grown on the ceramic tube via a simple wet-chemical route. The structural and composition information were examined by means of X-ray diffractometer, field emission scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. It is found that the diameters of these nanorods are uniform in the range of 50–200 nm and doping Pd did not change the morphology and diameter. Furthermore, trimethylamine gas sensing properties of these nanorod arrays were systematically investigated. The sensing measured results showed that doping Pd could obviously reduce operating temperature compared to pure ZnO nanorod sensor. Moreover, 1 mol% Pd-doped ZnO nanorod sensor exhibited significantly improved sensing performances to trimethylamine including enhanced response, short response/recovery time, good reproducibility and stability, good selectivity. Meanwhile, the enhanced sensing mechanism of Pd-doped ZnO nanorods was also discussed, which could be explained by the chemical and electronic sensitization theory. Our studies provide a facile in-situ sensing device synthesized route, which could be developed to synthesize other metal oxide sensing device. Moreover, design and formation of Pd-doped ZnO nanorod arrays have potential application for fabricating high performance trimethylamine sensors. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • The modification of APTES promoted adsorption of Ag nanoparticles on the SiO 2 matrix. • SERS enhancements increase with number of AgNPs on SiO 2 nanospheres surface. • SiO 2 /AgNPs nanospheres show highly uniformity. Abstract Sensitive substrate is the key factor, which may affect the enhancement effect of the SERS detection. SiO 2 /Ag hybrid nanospheres were synthesized by using (3-Aminopropyl) trimethoxysilane (APTES) modified SiO 2 nanospheres and [Ag(NH 3) 2 ]+ ions, which would be used as very sensitive and homogeneous surface enhanced Raman scattering (SERS) substrates. Our results show that the –NH 2 groups were grafted on the surface of SiO 2 due to the modification of APTES, which promoted adsorption of Ag nanoparticles on the SiO 2 matrix. The effects of APTES on the micromorphology, chemical structure, and SERS performance of SiO 2 /Ag hybrid nanospheres were investigated by the SEM, XRD, and SERS measurements. Results indicated that the Ag nanoparticles were crystalline and the diameter of AgNPs ranged from 50 to 100 nm. SERS measurement showed that the surface electromagnetic enhancement would increase with number of AgNPs on SiO 2 nanospheres surface, and the mechanism explained by the FDTD simulation. Furthermore, our results indicate the highly uniformity and reproducibility of these substrates with the relative standard deviation (RSD) of peak intensity was 7.74%. The SiO 2 /Ag nanospheres with had high sensitivity, uniformity and reproducibility should be potential SERS applications. [ABSTRACT FROM AUTHOR]

Highlights • Stress is not a linear approximation of composition in both W-Fe and W-Cr systems. • Zero-stress W-97Fe film didn't have the solute segregation present in the GBs. • Zero-stress W-80Cr film had a large grain size with laminate phase separation. • Upon heating during deposition, W-97Fe and W-80Cr films became compressive. • At 673K, W GB segregation in W-97Fe film and laths thickening in W-80Cr film. Abstract A series of W-Fe and W-Cr thin films were sputter deposited and the intrinsic growth stresses determined by in situ wafer curvature measurements. Under the growth conditions studied, the elemental W film grew in a compressive stress state whereas the elemental Fe and Cr films grew in a tensile stress condition. By mixing Fe or Cr with W, the alloy stress state was bounded between the two elemental stresses which included a zero stress condition. The specific stress response is reported as a function of alloy type that is affected by grain size, grain boundary composition, localized phase separation, and energetic peening effects. Using the ambient temperature deposited zero stress composition, these films were re-deposited at 673K to drive the microstructure towards equilibrium. Under these conditions, both alloys exhibited similar compressive stress states during post-coalescence growth, with the post-deposition stress recovery being greater in the W-Fe film than that of the W-Cr film. This difference was contributed to the dissimilarity in grain sizes between the two films as well as how the solute partitioned in the matrix, i.e. at the grain boundary or as phase separated laths within the grains. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Highly textured, semiconducting and hydrophobic Bi thin films by thermal evaporation. • Structure-property correlations by XRD, Raman, AFM, FESEM and wettability studies. • Oblique angle deposition enhances the surface roughness and reduces the conductivity. • Enhancement of hydrophobicity of Bi films by angled deposition. Abstract Oblique angle deposition is a promising technique for tuning the physical properties of thin films. Structural, surface morphology, electrical and wettability properties are strongly influenced by the angle of deposition. A comparison of these physical properties of normally and obliquely deposited Bi films is carried out in this study. X-ray diffraction studies show that films have highly oriented hexagonal crystal structure and crystallite size is smaller for obliquely deposited (70 nm) film as compared to that of normally deposited film (111 nm). Raman spectra of the films consist of peaks corresponding to E g and A 1g first-order Raman modes of bismuth. The atomic force and scanning electron microscopy studies show that the surface roughness of obliquely deposited film is higher as compared to that of normally deposited film. Contact angle measurements reveal that both films are strongly hydrophobic in nature with the contact angles of 105 ± 1° and 119 ± 1° for normally and obliquely deposited films respectively. Oblique angle deposition enhances the hydrophobicity of the film. The electrical conductivity of the film is significantly reduced by oblique angle deposition. The activation energies for electrical conduction were determined by four-probe measurements and are 0.0166 ± 0.0003 eV and 0.0178 ± 0.0003 eV for normally and obliquely deposited films respectively. [ABSTRACT FROM AUTHOR]

Highlights • ZnO NWs properties can be controlled by solution and hydrothermal process parameters. • The surface energy of substrate influences the growth morphology of ZnO NWs. • Shape and crystallography of ZnO NWs may be improved by monitoring substrate surface. Abstract Zinc oxide nanowires (ZnO NWs) have been synthesized by hydrothermal method on several substrate materials, in different conditions, with or without of a seed layer prepared by sol-gel process. The properties of ZnO NWs were easy and effectively controlled by a variety of parameters, such as: concentration and pH of solution, temperature and time of hydrothermal process. Based on experimental data, this study points out that the substrate properties can influence the orientation and the aspect ratio of ZnO NWs. This is due to the surface energy, which can be modified using surface agents, measured and monitored. Thus, the choice of surface substrate may be another option to improve some applications based on ZnO NWs. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • NiMoO 4 /NiO nanoflowers is synthesized via a facile and efficient method. • NiMoO 4 /NiO exhibits an excellent capacitance of 10.3 F cm−2 (1982.3 F g−1). • A high-performance ASC is fabricated using the NiMoO 4 /NiO as anode. Abstract Currently, although some progress has already been achieved, the complex and high-cost synthetic route, and low electrochemical properties of supercapacitor still restrict its practical application. Here, NiMoO 4 /NiO nanoflowers material with a high specific surface area grown on a nickel foam conductive substrate is successfully synthesized via a facile and efficient method, which exhibits an excellent capacitance of 10.3 F cm−2 (1982.3 F g−1), a good rate capability, and a remarkable cycling stability (capacity remain 98.6% after 3000 cycles). In addition, a novel asymmetric supercapacitor with excellent energy density is also fabricated via the NiMoO 4 /NiO nanoflowers as the positive electrode and a piece of active carbon as the negative electrode in 3 M KOH electrolyte. The optimized asymmetric device operating at 1.7 V also offers a high energy density and an outstanding long-term cycling stability. These impressive results suggest that such NiMoO 4 /NiO nanoflowers can pave the way for designing and developing next-generation high-performance storage systems. [ABSTRACT FROM AUTHOR]

Highlights • High quality Al 2 O 3 & HfO 2 /Al 2 O 3 on 2D materials was grown by low T ALD/CVD. • Sub nanometer AlOx particles provided nucleation centers on 2D material surfaces. • 2 nm thick Al 2 O 3 was uniformly deposited on high aspect ratio Si 3 N 4 /SiO 2 /Si fins. • C max of 2.7 µF/cm2 was achieved with MoS 2 and HOPG MOSCAPs using Pd/Ti/TiN gates. • MoS 2 MOSCAP had lower D it than Si 0.7 Ge 0.3 (0 0 1) indicating Van der Waals interaction. Abstract Al 2 O 3 and Al 2 O 3 /HfO 2 bilayer gate stacks were directly deposited on the surface of 2D materials via low temperature ALD/CVD of Al 2 O 3 and high temperature ALD of HfO 2 without any surface functionalization. The process is self-nucleating even on inert surfaces because a chemical vapor deposition (CVD) component was intentionally produced in the Al 2 O 3 deposition by controlling the purge time between TMA and H 2 O precursor pulses at 50 °C. The CVD growth component induces formation of sub-1 nm AlOx particles (nanofog) on the surface, providing uniform nucleation centers. The ALD process is consistent with the generation of sub-1 nm gas phase particles which stick to all surfaces and is thus denoted as nanofog ALD. To prove the ALD/CVD Al 2 O 3 nucleation layer has the conformality of a self-limiting process, the nanofog was deposited on a high aspect ratio Si 3 N 4 /SiO 2 /Si pattern surface; conformality of >90% was observed for a sub 2 nm film consistent with a self-limiting process. MoS 2 and HOPG (highly oriented pyrolytic graphite) metal oxide semiconductor capacitors (MOSCAPs) were fabricated with single layer Al 2 O 3 ALD at 50 °C and with the bilayer Al 2 O 3 /HfO 2 stacks having C max of ∼1.1 µF/cm2 and 2.2 µF/cm2 respectively. In addition, Pd/Ti/TiN gates were used to increase C max by scavenging oxygen from the oxide layer which demonstrated C max of ∼2.7 µF/cm2. This is the highest reported C max and C max /Leakage of any top gated 2D semiconductor MOSCAP or MOSFET. The gate oxide prepared on a MoS 2 substrate results in more than an 80% reduction in D it compared to a Si 0.7 Ge 0.3 (0 0 1) substrate. This is attributed to a Van der Waals interaction between the oxide layer and MoS 2 surface instead of a covalent bonding allowing gate oxide deposition without the generation of dangling bonds. [ABSTRACT FROM AUTHOR]

Pristine Bi 2 WO 6 hollow microspheres have been fabricated in ethylene glycol-water system with CTAB as crystal growth director for the first time, hybrid Au- Bi 2 WO 6 hollow microspheres was also obtained by in situ decoration of Au nanoparticles, the formation mechanisms were explored. Their photocatalytic activities on photo-reduction of Cr(VI) and photo-degradation of phenol in aqueous solution were investigated under visible light irradiation. Hybrid Au- Bi 2 WO 6 hollow microspheres displayed the highest photocatalytic activity, exhibiting a nearly complete reduction of Cr(VI) to Cr(III) within only 20 min. The excellent photocatalytic activities of heterogeneous Au-Bi 2 WO 6 hollow microspheres can be induced by the increased light harvesting efficiency (due to light multi-scattering effect of hollow architecture), high separation of photogenerated electron-hole pairs caused by electron trapping effect and surface plasmon resonance (SPR) effect of Au nanoparticles. [ABSTRACT FROM AUTHOR]

This work addresses the development of a magnetically extractable magnetite-silica-titania photocatalyst to be applied in the degradation of organic compounds in water. MCM-41 silica was successfully deposited on magnetite, providing large surface area for anchoring of TiO x species, and preventing thermally induced conversion of magnetite to hematite. A good correlation between the calculated values and amount of titania deposited on the silica-covered magnetite particles was obtained for a synthesis route involving the treatment of magnetite-silica in boiling ethanolic Ti-precursor solution. Photocatalytic activity in conversion of 4-chlorophenol could only be observed for compositions containing larger than ∼50 wt% titania, whereas increasing the titania content did not significantly improve performance. Experiments carried out at pH ∼ 3.0 and ∼7.2 demonstrated the performance is relatively pH-independent. The structure activity-correlation of the materials is briefly discussed. [ABSTRACT FROM AUTHOR]

A novel flower-like nanostructured V 3 S 4 /graphene aerogel (V 3 S 4 -GA) hybrid is successfully synthesized as an efficient electrocatalyst for oxygen reduction reaction (ORR). The flower-like V 3 S 4 homogeneously grows on the surface of graphene, which provides a large contact surface area with electrolyte and abundant active sites. The strong covalency of VsbndS bond and the abundant unoccupied d-orbits of vanadium atoms are propitious to the exchange of the adsorbed oxygen molecular. The porous GA exists an excellent continuous electric conductive network for electron transportation and enough nanospace for O 2 adsorption and reaction. Such unique nanostructures offer the synthesized V 3 S 4 /GA hybrid an excellent ORR catalytic performance, including a high electron transfer per oxygen molecule of 3.97, a high kinetic current density of 9.5 mA cm −2 at −0.5 V vs. Ag/AgCl, a high methanol resistance and a good durability. [ABSTRACT FROM AUTHOR]

CO 2 reduction on a catalytic surface is a very attractive research for energy and environments. In the present study, CO 2 with H 2 O was found to be reduced to CO on an aluminum foil surface with evolution of H 2 , which resulted in the growth of stalagmite Al(OH) 3 on this surface. The reduction was found to be highly temperature dependent. The crystal growth and the changes in the crystal structure were confirmed by scanning electron microscopy, high resolution transmission electron microscopy, X-ray diffraction crystallography, FT-IR, and Raman spectroscopy. The surface chemical oxidation states were examined by Auger elemental mapping and X-ray photoelectron spectroscopy. The reaction mechanism was proposed to 2Al + CO 2  + 5H 2 O → 2Al(OH) 3  + CO + 2H 2 . The evolution of CO and H 2 was confirmed by gas-chromatography and gas sensors. These new findings highlight the potential of performing the reduction of CO 2 on a metal surface by understanding its surface reactions. [ABSTRACT FROM AUTHOR]

An antisolvent (iodobenzene, IB) was used to assist the formation of closely packed CH 3 NH 3 PbI 3 (MAPbI 3 ) thin films during the one-step spin-coating process using different volumes of IB. The morphological, structural, optical and excitonic properties of MAPbI 3 thin films were analyzed using a contact-mode atomic-force microscope, X-ray diffractometer, broadband absorbance spectrometer and optical microscope-based time-resolved photoluminescence spectrometer. The properties of the resultant MAPbI 3 thin films can be manipulated by using different IB volumes, which dominates the device performance of MAPbI 3 based photovoltaic cells. The experimental results show that the grain size (or particle size) of MAPbI 3 thin films influences the collection of photoexcited carriers and the contact at the 6,6-Phenyl C 61 butyric acid methyl ester (PCBM)/MAPbI 3 interface, thereby resulting in a trade-off between the fill factor (FF) and short-circuit current density (J SC ). In addition, it is predicted that the power conversion efficiency (PCE) can be further improved by increasing the crystallinity of the MAPbI 3 thin film while keeping the small grain size. [ABSTRACT FROM AUTHOR]

With the eventual aim of forming joints between superconducting wires of YBa 2 Cu 3 O 7−δ (YBCO), thin films of Nb were grown at room-temperature on SrTiO 3 (STO) (0 0 1), a single-crystal substrate that shows good lattice matching with YBCO. The crystallinity, surface morphology, and superconducting properties of the Nb thin films were investigated and compared with those of similar films grown on a silica glass substrate. The Nb thin films grew with an ( hh 0) orientation on both substrates. The crystallinity of the Nb thin films on the STO substrate was higher than that on the silica glass substrate. X-ray diffraction measurements and observation of the surface morphology by atomic-force microscopy indicated that Nb grew in the plane along the [1 0 0] and [0 1 0] directions of the STO substrate. This growth mode relaxes strain between Nb and STO, and is believed to lead to the high crystallinity observed. As a result, the Nb thin films on the STO substrates showed lower electric resistivity and a higher superconducting transition temperature than did those on the silica glass substrates. The results of this study should be useful in relation to the production of superconducting joints. [ABSTRACT FROM AUTHOR]

Magnetic nanocomposite composed of attapulgite and Fe 3 O 4 was synthesized by a simple and facile co-precipitation method. Its structure and morphology was verified using X-ray diffraction, transmission electron microscopy, scanning electron microscopy and Fourier transform infrared spectroscopy. Although the difficulty of forming uniform Fe 3 O 4 on the attapulgite surface was discussed in detail in this study, one-dimensional magnetic nanorod with attapulgites as core and Fe 3 O 4 as uniform shell was implemented for the first time using a cationic polymer surfactant, polyethylenimine. Polyethylenimine concentration, Fe 3+ /Fe 2+ concentration and temperature were controlled to investigate the morphological evolutions of this nanocomposite. It was found that a uniform shell could be available with thickness tuning from 10 nm to 40 nm when Fe 3+ concentration ranged from 0.01 mol/L to 0.03 mol/L meanwhile the polyethylenimine concentration was kept at 0.2 mg/mL and the temperature was kept at 60–80 °C. Finally, a possible mechanism for the formation of the Fe 3 O 4 shell was suggested. The polyethylenimine on the surface of the attapulgites first adsorbed Fe 3+ /Fe 2+ and then released under the action of alkali. It acted as a linker for the Fe 3 O 4 nanoparticles nucleation in situ. The synthesized one-dimensional nanocomposites exhibit the superparamagnetism and fast response to an external magnetic field. The alignment of attapulgite-Fe 3 O 4 one-dimensional nanocomposite along the external magnetic field was demonstrated. It provides promising candidates for building blocks and functional devices, which are low cost, non-toxic and eco-friendly, and opens the door for the application of attapulgite as one-dimensional nanomaterials. [ABSTRACT FROM AUTHOR]

The formation of islands of O-atoms is the dominant mode of growth of the oxide in the first stages of oxidation of Al(1 1 1). It is however unknown if a similar mechanism exists for other low index surfaces of Al. We performed a density functional theory (DFT) and ab initio molecular dynamics investigation of the first stages of the oxidation of Al(1 1 0) using two distinct models: a homogeneous surface disposition of O-atoms; and a model where the O-atoms are close-spaced forming clusters or islands. We investigated the surface reactions with oxygen up to a coverage of 2 ML and found that for both models the adsorption energy per dissociating O 2 (g) becomes more negative with increasing coverage. Our results show that for coverages up to 1.25 ML the oxide forms clusters or islands while for coverages higher than 1.5 ML the oxide covers the surface homogeneously. This is because the O-atoms bind preferably to neighboring sites even at the minimum coverage. With increasing coverage, the clusters of O start to form stripes along the [1  1 ¯  0] direction. The work function ( ϕ ) of the surface decreases when going from bare Al(1 1 0) to up to 1 ML coverage of O-atoms, but for coverages of 1.25 ML and higher, ϕ increases. The Al 2p surface core level shifts (SCLS) shift towards higher binding energies with increasing surface coverage of O-atoms and start to approach the values of Al 2p in Al 2 O 3 already at a coverage of 2ML. A relation between the SCLS and the coordination number of Al to O-atoms was made. The Al 2p SCLS increases with increasing coordination to O-atoms, for single, twofold and three-fourfold coordinated cations. For the O-atoms that terminate the surface at the short-bridge sites, the SCLS of O 1s, is largely affected by the proximity to other O-atoms. These results demonstrate that the cooperative effects between surface bound O-atoms have important roles in the mechanism of growth of the oxide at Al(1 1 0), and similarly to what happens for Al(1 1 1), the initial oxidation of Al(1 1 0) proceeds via the formation of islands of O-atoms. [ABSTRACT FROM AUTHOR]