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We consider a second order boundary value problem with a parameter. A new upper bound for positive solutions and Green’s function of the problem is obtained.

The superior performance of WO3–SBA-15 for epoxidation was attributed that the abundant isolated WO4 benefited the coordination and activation of H2O2, and strong electron-withdrawing by the support facilitated weakening the bond strength of the O–O bond in W–OOH.

In most cases, the blasting object is the rock mass. Because the rock mass has the characteristics of anisotropy and inhomogeneity, there are often structural surfaces such as joints, fissures, faults, and weak interlayers, but details are basically impossible. Compared with the rock, these structural surfaces are weak parts, and the explosive energy required for breaking is smaller. It is difficult to take into account the existence of each weak side when the explosives are arranged in the blasthole. Therefore, after the explosive explodes in the rock mass, the explosive gas will first rush out from these weak parts, entraining individual fragments to form flying rocks. Aiming at the problem that it is difficult to accurately obtain the rock motion information in the blasting process of open-pit mines, this paper selects the kernel function to establish the support vector machine model and optimizes the parameters of the support vector machine model to obtain the optimal blasting rock trajectory prediction model. Under the protection of special protection devices, the information of the rock movement during the blasting process is collected at a higher frequency, and the analysis algorithm of the rock movement characteristics is researched on the basis of inertial navigation technology. The algorithm is used to analyze and output the rock movement. The curve of velocity, position, and kinetic energy provides a theoretical and technical basis for the study of rock movement law in the blasting process of open-pit mines. Through the experimental analysis, based on the cross-validation method, through the support vector machine model parameter optimization and comparison evaluation parameters, the optimal prediction model of the blasting rock trajectory is obtained as the support vector machine model based on the radial basis kernel function. The mean value of root mean square error and mean absolute error of this model are 0.102 and 0.0674, respectively, and the performance is the most robust among the three types of models.

The introduction of oxygen vacancies improved 1-hexene epoxidation performance over WO3−x/SBA-15 catalysts, which is attributed to the enhanced Lewis acidity of the active centers and the reduced energy barrier of the rate-determining step.

The catalytic liquid-phase oxidation of 1-hexene with O2 using Ag/porous bowl-shaped alumina shows good selectivity for the epoxidation product.

A new strategy was developed to control the exposed facets of α-Fe2O3 through oriented attachment along the [001] direction by utilizing the polar {001} facets of α-Fe2O3, and the facet-dependent catalytic performance was explored.

An in-depth understanding of the gravity flow behaviour of broken ore is beneficial to improving the ore recovery in sublevel caving mines. In this study, granular dolomites were used as an analogue to experimentally explore the effect of the physical properties of fragments on the gravity flow behaviour of broken ore. Five groups of granular dolomites were prepared first. Then, the particle size, particle size distribution, and particle morphology (e.g., sphericity, circularity, and fractal dimension) in each group were measured following the standard particle morphology test. After that, the angle of repose and the isolated extraction zone (IEZ) of each group were determined by performing funnel and isolated draw experiments, respectively. The experimental results highlighted the insubstantial effect of particle size and the significant effect of particle morphology on the angle of repose and isolated extraction zone of granular dolomite. It was found that a wider particle size distribution yielded an isolated extraction zone with a nonuniform shape and a smaller mass drawn because of the percolation of finer particles and the jamming of larger particles. Further, a linear negative correlation was revealed between the repose angle and the IEZ mass. Establishing the relationship between the repose angle and the IEZ shape would be of great significance. In this regard, the findings of this study can aid a preliminary analysis.

In this work, c-axis-oriented continuous GaN films have been synthesized by the chemical vapor deposition (CVD) method using ZnO material as the intermediate buffer layer. The GaN films with different growth temperatures exhibit high crystal quality and small surface roughness due to the same crystal structure and low lattice mismatches rate between GaN and ZnO materials. Meanwhile, the UV photodetector based on the CVD-grown GaN film exhibits a relatively high responsivity, fast rise and decay time, and good thermal stability. Our work provides a simple and promising CVD method to fabricate continuous GaN film for electronic and optoelectronic devices.

Ultraviolet detectors are widely used in space exploration, military affairs, and disinfection. To further improve the responsivity and response time, we propose and demonstrate AlN three-dimensional metal-semiconductor-metal (3D-MSM) and flip chip 3D-MSM (FC-3DMSM) ultraviolet detector here. The performance of devices with different etching depth and electrode spacing has been investigated using APSYS simulation. According to the simulation results, we fabricated $0.5~\mu \text{m}$ -etched 3D-MSM (3D-MSM- $0.5~\mu \text{m}$ ) and $1.3~\mu \text{m}$ -etched FC-3DMSM (FC-3DMSM- $1.3~\mu \text{m}$ ) devices. Response time is decreased by 29.3% and 13.8% for 3D-MSM- $0.5~\mu \text{m}$ and FC-3DMSM- $1.3~\mu \text{m}$ devices, and responsiveness exhibits a 20.5% and 46.6% improvement at 200nm, compared with traditional MSM device. This is due to varied internal electric field distribution of 3D-MSM and FC -3DMSM device configuration, which accelerates the collection of photo-generated carriers and improves the carrier collection efficiency. Our work should advance the development of nitrides ultraviolet detectors.

The confinement effect known as efficient strategy to enhance the heterocatalytic activity and stability, but a clear view regarding the role of encapsulated overlayers is far from convincing at present, especially, the penetration of substrates with different size. Herein, the experimental evidence about the impacts of BN overlayers on hydrogenation is obtained over Co@BN/BN model catalysts with tuned thinness, in which BN overlayers encapsuled Co particles that dispersed on the defective BN supports, fabricating by the nitridizing of ball-milled BN microplates under NH

With the increasing demand for thermal management for high-power electronics devices and modules, a variety of double-sided cooling (DSC) encapsulation modes have emerged. In this article, we focused on the planner packaging structure and solder bump interconnection applied in DSC power modules, thermal management, and thermomechanical reliability were compared based on finite-element method under different power losses, temperatures, and temperature cycling. Results show that planner structure with copper buffer has lower junction temperature versus solder bump interconnection and lower thermal stress of the module is generated. However, chip stress of the planner packaging is high, especially under the same temperature. The planner stretches caused by normal stress is the major factor that affects the thermal stress of chip. With underfilling, reliability of solder bump is improved due to a lower plastic strain and plastic work yet simultaneous increased thermal stress. This study should advance the package of DSC modules.

This study reports treatment of low-zinc EAF dust for obtaining high-grade metallized product with a focus on multiple valuable elements via microwave reduction followed by magnetic separation. In reduction, the conversions of components of iron, zinc, lead, manganese and chromium, mainly in the form of spinel phases, to Fe, Zn, PbCl2, MnO and Cr2O3, respectively, were partially restrained by the formation of complex silicates, e.g., Ca3Al0.84Fe1.16Si3O12. After microwave reduction under the conditions of C/Fe mass ratio of 0.25, temperature of 1323 K, dwell time of 15 min, heating rate of 25 K/min and microwave power of 2200 W, the reduced briquette had the iron metallization degree of 96.20%, with volatilization of 98.38% of Zn and 80.22% of Pb. By magnetic separation, a high-grade metallized product containing 81.77 wt% Fe (79.97 wt% metallic iron) and 0.04 wt% Zn, satisfying the Chinese standard (YB/T 4272–2012) of the first-grade metallized product from dust, was obtained.

Thermal compression bonding (TCB) has been widely used in flip chip bonding processes for three-dimensional integrated packaging. Therefore, studying the TCB process and solder joint structure is significant for improving reliability. In this study, a Ni layer was deposited between the Cu/Sn-3.5Ag solder bumps of upper and lower chips, and TCB process tests were carried out at different bonding temperatures, forces and times. The solder height at the top and bottom of the copper pillar were recorded. Through the establishment of a mathematical analysis model, the relationship between the solder joint height and maximum stress was analyzed theoretically, and the trend of the shear stress and solder joint height was obtained from die shear tests. Then, the solder joint morphology, strength and microstructure composition of the microbumps were observed after aging. Our results showed that the growth rate of intermetallic compounds (IMCs) for Cu/Sn-3.5Ag microbumps with a 25 μm diameter was 2.5 times those with a 100 μm diameter and that the Ni barrier layer prevented the diffusion of Cu in Sn-3.5Ag solder. In addition, the Ni layer improved the strength of the Cu/Sn-3.5Ag joints after aging. Finally, with extended aging time, the fracture site was found to move from the solder region to the Cu6Sn5 layer for the Cu/Sn-3.5Ag samples, while it remained at the Sn-3.5Ag/IMC interface for the Cu/Ni/Sn-3.5Ag samples.

To dispose the problem of ferronickel slag for its value-added application, it was used for preparing thermal insulation materials by sintering of the slag in the presence of another waste, fly ash cenosphere (FAC), as pore former. The thermodynamic and experimental analyses revealed that the original phase of the slag, olivine, could be transformed to thermal insulation phases, including enstatite and cordierite, by optimizing sintering temperature in the range 1100–1300 °C. Specifically, after initial decomposition of ferronickel slag, there existed a low-iron olivine phase and cordierite and enstatite became the dominant phases when the sintering temperature increased from 1100 °C to 1300 °C. Except for the phase transformation, the microstructural evolution with proper pore features (porosity and size) contributed to a resulting material with desirable thermal and mechanical properties. It was shown that the ferronickel slag sintered at 1200 °C for 2 h with the addition of 25 wt % FAC exhibited the optimal thermal and mechanical performance. Additionally, it possessed good acid and alkali resistances. The results confirmed the feasibility of co-utilization of ferronickel slag and FAC for producing superior thermal insulation materials at a proper temperature, making efficient utilization of both wastes.

A three-dimensional (3D) display provides an immersive user experience and represents the frontier of display technology. The 3D display based on polarizer films is relatively mature. However, the currently used polarizer films lead to bulk systems and low efficiency. Micro-light-emitting diodes (micro-LEDs) have the advantages of small size, high contrast, low power consumption, and high response frequency. The 3D micro-LED displays combine the characteristics of 3D display and the advantages of micro-LEDs simultaneously, which can be used in portable electronics or micro-LED projectors and provides users with 3D experience. Here, linearly polarized (LP) micro-LEDs with varied chip diameters are numerically and experimentally investigated. Subwavelength metal gratings are integrated directly on the p-GaN of micro-LEDs. A maximum extinction ratio of 14.17 dB and a corresponding energy loss of 50% are achieved directly from LP micro-LEDs under the injection current density of 200 A/cm2. The size-dependent effect of LP micro-LED is also investigated and it is found that smaller sized LP micro-LEDs have smaller extinction ratio due to sidewall light leakage. The reported GaN-based LP micro-LEDs have excellent potential to be utilized in 3D micro-LED displays.

Several methods that could effectively increase the strength of heavy aluminum bonding wire and broaden the scope for high-power IGBT module applications with a high degree of integration have been proposed. In this work, a series of finite element analysis has been carried out to study the thermomechanical reliability of bonding wire/ribbon under different conditions. The effects of structural loop parameters, bonding wire materials, bonding ribbon, and polymer coating are discussed based on simulation results, and the primary cause for the effect of geometric parameters has been developed. It is worth noticing that the reliability of the heavy bonding wires increases with the increase in Young’s modulus and Poisson’s rate in a polymer coating. This present study provides new insights into the thermomechanical behaviors of heavy bonding wire/ribbon, as well as a practical guide for designing an optimal structural loop shape and selecting an appropriate material of bonding wires or polymer, which will accelerate functional applications in industries.

High-crystal-quality nonpolar indium nitride (InN) nanoplates were synthesized via deploying controllable chemical vapor deposition (CVD) technology using the M-plane of GaN nanowires (NWs) as a template, with features creating a potential advantage for their use in terahertz emitter/detector devices. The formation of the 2D InN nanosheets may have been due to self-limiting epitaxial growth, which is in turn explained by lattice induction theory and surface distortion effects.

Micron-sized Fe3O4 is a practical anode material that is used in industrial Ni–Fe batteries, and its ability to simultaneously achieve high capacity and excellent rate capability is very practical and is urgently needed. In this work, through etching industrial Fe3O4 particles, hydrophobic mesoporous Fe3O4 sheets can be regenerated, and can be dispersed around micron-sized Fe3O4 particles when the slurry dries to form a coating on the current collector. These hydrophobic mesoporous sheets in the electrode can improve the electrochemical reaction kinetics and alleviate the volume expansion of micron-sized Fe3O4 particles, which is a new and effective way to simultaneously achieve high capacity and excellent rate capability. Our results show that when this electrode is coupled with the NiS cathode, the battery exhibits the capacity of 221.17 mA h g−1 at 0.2 A g−1, and excellent cycling stability of 92% of the initial capacity after 50 cycles, revealing significant performance improvement. Compared with the common strategy of carbon-coating Fe3O4 particles to improve the battery performance, this strategy of functionalizing Fe3O4 particles with hydrophobic mesoporous sheets is more favorable for performance improvement and large-scale application.

Solid diffusion bonding of the copper–zinc system is preliminarily investigated as a possible bonding solution for power modules. This article proposed a method of bonding Zn foil on substrate-plated Ag to obtain the solder joints. The formation and transformation of intermetallic compounds (IMCs) in Cu–Zn and Ag–Zn joints were investigated. The results showed that the AgZn3 phase was compressed and moved into the solder side when competed with the Cu5Zn8 phase, relieved the Kirkendall voids, and enhanced the connection of joints. Besides, the electrical resistivity could maintain at a competitive level of $9~\mu \Omega \cdot {\mathrm {cm}} $ , and the shear strength reached 43–75 MPa. These properties were also appreciated even after the aging test. The deformation behaviors of different IMCs were tested by nanoindentation. This work provides a potential alternative to high-temperature solders used for high-power-density electronic packaging applications.

The oxidative desulfurization (ODS) of fuel oils is of great significance for environmental protection, and the development of efficient ODS heterogeneous catalysts is highly desired. Herein, we ha...

A novel strategy for selective recovery of chromium from ferronickel slag via microwave assisted sodium peroxide roasting followed by water leaching was proposed in this study. The experimental results showed that 94.21% of chromium was leached with 64.43% of sodium and 6.13% of silicon, while only 0.06 wt% chromium remained in the leaching residue when the mixture of ferronickel slag and sodium peroxide with the mass ratio of 1 was roasted at 600 °C for 20 min before leaching at 50 °C for 1 h with the liquid-to-solid ratio of 10 mL/g. In comparison with conventional roasting, the microwave roasting showed a much higher efficiency for recovering chromium from ferronickel slag with the recovery of chromium increased by 12.92%, resulting from the enhanced conversion of Cr2O3 in the slag to NaCrO2 and from the looser and more porous structure during the roasting process which was beneficial for subsequent water leaching.

The ethanol oxidation reaction is of critical importance to the commercial viability of direct ethanol fuel cell technology. However, owing to the poor C-C bond cleavage capability, almost all ethanol oxidation is incomplete and suffers from low selectivity toward the C1 pathway. Herein, under the support of theoretical calculations that the heterointerfaces between CoP and Pd can reduce the energy barrier of C-C bond cleavage, rich heterointerfaces in CoP/RGO-Pd hybrids were designed to improve ethanol electrooxidation performance through enhancing the selectivity toward the C1 pathway. The experimental results show that the faradaic efficiency of the C1 pathway of CoP/RGO-Pd hybrids is as high as 27.6%, surpassing most reported catalysts in the literature. As a result of this enhancement, CoP/RGO-Pd10 exhibits mass activity as high as 4597 mA·mg

The metal-free BN catalyst is a competitive candidate in oxidative dehydrogenation (ODH). The popular oxidant used is molecular O2, and the alternative soft oxidant, CO2 with better selectivity, is...

A series of Fe/h-BN catalysts promoted with Cu or Mn were prepared for Fischer-Tropsch synthesis (FTS). The physicochemical properties, crystal structures and morphologies of the catalysts were characterized by N2 physisorption, FT-IR, TPR, XPS, XRD, MES and TEM. It is found that iron oxide nanoparticles are highly dispersed on h-BN matrix due to the anchoring effect of surface defects and the accommodation of porous structures of h-BN. The characterization results indicate that strong interaction between iron oxide and h-BN is present on un-promoted catalyst, which endows the h-BN supported iron catalyst with stable properties under FTS conditions but severely retards reduction of the catalyst. The addition of Cu to Fe/h-BN can to some extent overcome the strong interaction by introducing more sites for dissociating H2. It is observed that Cu promoter can increase the reduction or carburization degree and thus enhance the FTS activity. The addition of Mn to Fe/h-BN can weaken the strong interaction by altering the electron structure of iron species. And the electron-rich Fe species are responsible for easy reduction and the enhanced FTS performance. Besides, a higher activity can be realized by co-adding Cu and Mn to the Fe/h-BN catalyst. These results suggest that the synergistic effect of Mn and Cu can largely improve the performance of Fe/h-BN catalyst without impairing the stability of the catalyst. The present study paves a way to tailor the performances of FTS catalysts with h-BN as support.

For crystalline catalysts with special morphology, the corners and edges are usually of high activities due to the presence of unsaturated coordination sites, so it will be an ideal strategy to promote catalytic properties by only keeping the corners and edges of such kinds of catalysts. In this work, a Cu2O tetradecahedral nanocage with plenty of corners and edges was formed by selectively etching the (111) and (100) facets on the basis of a simple top-down method, in which SDS was used as a protective agent to keep the active corners and edges while hydroxylamine hydrochloride was used as a reducing agent and an etchant. The decomposition of ammonium perchlorate (AP) was used as a probe reaction to test its catalytic performance. It was found that the low temperature decomposition (LTD) and high temperature decomposition (HTD) were reduced by 27.1 °C and 107 °C, respectively, and the heat release increased by three times in comparison with pure AP. The Cu2O nanocage exhibits excellent activity and high catalytic performance in the reaction. This work provides us an effective AP thermal decomposition catalyst and a simple strategy to fabricate a hollow structure with low-energy facets etched and highly active facets exposed.

To improve the performance of III-nitride compound semiconductor-based optoelectronic devices, highly reflective distributed Bragg reflectors (DBRs) are a requirement. In this report, AlN and Al1−xInxN layers were first sputtered and characterized concerning their optical, structural and morphological properties. Ellipsometry measurements were used to determine the optical constants (refractive index, n and coefficient of extinction, k, in dependence of the wavelengths of the layers. The indium content of the Al1−xInxN film was investigated by X-ray photoelectron spectroscopy analysis. Subsequently, AlN/Al1−xInxN DBRs with high reflectivity spectra operating in the UV A, B and C were designed and fabricated on Si (111) and SiO2 substrates by radio frequency (RF) magnetron sputtering. The DBRs consist of an eight-pair AlN/Al0.84In0.16N at 235 nm, 290 nm and 365 nm with reflectances of 86.5%, 97.7% and 97.5% with FWHM of 45 nm, 70 nm and 96 nm, respectively. Atomic force microscopy analysis yielded a Root Mean Square (RMS) of 2.95 nm, implying that the DBR samples can achieve reasonable smoothness over a wide area. Furthermore, the impact of an annealing phase, which is frequently required during device growth, was investigated. Our findings indicate that AlN and Al1−xInxN are suitable materials for the fabrication of deep UV DBRs.

The contribution of the reverse spillover effect to hydrogen generation reactions is still controversial. Herein, the promotion functions for reverse spillover in the ammonia borane hydrolysis reaction are proven by constructing a spatially separated NiO/Al2O3/Pt bicomponent catalyst via atomic layer deposition and performing in situ quick X-ray absorption near-edge structure (XANES) characterization. For the NiO/Al2O3/Pt catalyst, NiO and Pt nanoparticles are attached to the outer and inner surfaces of Al2O3 nanotubes, respectively. In situ XANES results reveal that for ammonia borane hydrolysis, the H species generated at NiO sites spill across the support to the Pt sites reversely. The reverse spillover effects account for enhanced H2 generation rates for NiO/Al2O3/Pt. For the CoOx/Al2O3/Pt and NiO/TiO2/Pt catalysts, reverse spillover effects are also confirmed. We believe that an in-depth understanding of the reverse effects will be helpful to clarify the catalytic mechanisms and provide a guide for designing highly efficient catalysts for hydrogen generation reactions., H2 is regarded as an attractive green fuel and a promising energy carrier for the future. Here, the promotion functions of reverse spillover effects in the H2 generation reactions over bicomponent catalysts are revealed by performing in situ X ray absorption near edge structure characterization.

In this study, porous activated carbon balls supported by nanoscale zero-valent iron composites (Fe@PACB-700) were used for the first time for the removal of trace Cr(VI) from aqueous solutions. The Fe@PACB-700 composites were prepared by a facile carbothermal reduction method and then characterized by scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS). The results show that nZVI particles have been successfully loaded onto PACBs. Fe@PACB-700 shows an excellent Cr(VI) removal efficiency of 91.2%. The maximum adsorption capacity of Fe@PACB-700 for Cr(VI) is 22.24 mg/g, which is 4.36 times that of PACB. The residual Cr(VI) concentration is below 20 ppb with the use of 0.15 g of Fe@PACB-700, which is much lower than the allowable concentration for Cr(VI) in drinking water (0.05 mg/L). The adsorption of Cr(VI) can be well described by the Langmuir isotherm model and pseudo-second-order kinetic model. Fe@PACB-700 still has a high removal efficiency of 80% after five cycles. Thus, Fe@PACB-700 has a great potential for Cr(VI) removal from aqueous solution. Graphical abstract.

Augmented reality (AR) is emerging as a next-generation interactive display that promotes the interaction between users, digital content, and the real world. Although micro-LED is regarded as the most promising light engine candidate for AR, its inherent Lambertian radiation characteristics and relatively broader emission spectrum result in low optical coupling efficiency and diffraction dispersion-related “rainbow” phenomenon when combined with a waveguide combiner. Here, we numerically and experimentally demonstrate resonant cavity (RC) micro-LEDs by incorporating SiO2/TiO2 distributed Bragg reflectors with chip sizes of 60, 100, and 150 μm. The device has a divergence angle of 78.7° and a narrow spectrum width of 6.8 nm, which is significantly lower than that of the controlled micro-LEDs. The reported GaN-based RC micro-LEDs have the potential to be used in the display panel for AR applications in a variety of scenarios, including AR glasses, and head up display for cars and airplanes.

Micro-LED display is considered to be the most promising display technology, and naked-eye 3D display represents the most advanced frontier of display. Naked-eye 3D micro-LED display has both the advantages of micro-LED display and the characteristics of naked-eye 3D display. Only conceptual solutions for 3D micro-LED display have been reported so far. The effect of luminescence distribution and the direction of micro-LED devices on crosstalk in the naked-eye 3D display is not clear. In this paper, we first investigated the chip-shaping effect on the emission characteristics, mainly the luminescence distribution and direction of the micro-LED, and then we investigated the influence of luminescence distribution and direction of micro-LED on the pixel crosstalk in naked-eye micro-LEDs 3D display. Our work should advance the micro-LED display, especially the micro-LED 3D display.

In x Al 1–x N is beneficial for developing full-spectrum devices. The influence of growth parameters including reaction gas ratio, reaction pressure and growth temperature on In x Al 1-x N layers is investigated. We find the growth parameter of well-oriented film is 18sccm N 2 flow rate with 1:3 gas ration, 1Pa pressure and 200℃. The In 0.6 Al 0.4 N film device is fabricated with significant photo-respond and stable current. The saturation time is measured about 0.8~1.0s. Our work is meaningful for improving the photovoltaic properties of In x Al 1-x N devices in the future.

This Letter proposes a circularly polarized (CP) light GaN micro-LED which is integrated with functional metasurfaces. The one-dimensional metallic nanograting can achieve a high transverse electric (TE) reflectivity ( R T E ) and extinction ratio (ER) of TE and transverse magnetic (TM) waves, which is highly polarized output for micro-LEDs. Besides, the nanograting, which is integrated on the bottom of the GaN layer, can also support a resonant cavity, together with the top distributed Bragg reflector, which can shape the radiation pattern. By optimizing the structure parameters of nanograting, the R T E achieves over 80%, and the ER reaches higher than 38 dB at 450 nm for the GaN micro-LED. Additionally, the metasurface, which acts as a quarter-wave plate, was investigated to control the phase delay between the polarization state of the electric wave in two orthogonal components. Finally, the circular shape of the transmitted pattern denotes the high performance of the metasurface which is integrated in the micro-LED for CP light emission. The work reported in this Letter might provide potential application in a 3D polarized light display.

Boron nitride (BN) has attracted great attention with an unexpected ability in aerobic catalysis. Still, its related probe reactions are relatively rare, and the effect of the BN-supported metal catalyst on O2 activation is still ambiguous, and opinions are varied. In this work, the porous BN (pBN)-supported Au catalyst with a porous structure and exposed edges exhibits high activity in the oxidative cross-esterification reactions between the aromatic and C1-C3 aliphatic alcohols at ambient temperature. The turnover frequency value for methyl benzoate is 118 h-1 at 30 °C, and the calculated apparent activation energy (Ea, 58 kJ/mol) is comparable to that of AuPd/TiO2, Ru/Al2O3, and PdBiTe catalysts. Combined with temperature-programmed desorption (TPD) results, the loading of Au enhances the desorption of O2 and the interaction with alcohols; thus, a synergistic effect between the O-rich pBN and Au is considered. The free-radical scavenger can dramatically suppress the conversion (∼6%), suggesting that the reaction proceeds via the O2* radicals. According to the vibration of νO-O, δOO-H, and νB-O-O-B detected by attenuated total reflectance-infrared spectroscopy (ATR-IR), we are prone to consider the oxygen activation route by the edge B atoms. Then, a possible L-H reaction mechanism was proposed: benzyl alcohol and O2 adsorb on the Au/pBN initially, then O2 is converted to O2*, and the α-H elimination proceeds; as the semi-acetal formed, another α-H elimination proceeds and methyl benzoate is finally formed.

The surface chemistry of catalyst plays a vital role in the catalytic process. And the effects of surface groups of porous boron nitride (p-BN) on the hydrogenation reaction have not been studied in detailed. In this work, two main surface species of Co/p-BN catalyst were tuned thermally and their roles on the hydrogenation reaction were discriminated by α, β-unsaturated aldehyde hydrogenation reaction. The surface B O content decreased at higher reduction temperature and the cobalt phase changed from CoO to the mixture of CoO and Co0. The Co/p-BN-500 exhibited the highest selectivity to C O hydrogenation. And its turnover frequency (TOF) of 13.2 h−1 is close to the optimal value of reported cobalt catalysts. When the reaction proceeds, hydrogenation rate of C O increases but that of C C decreases gradually, thus a surface groups variation was expected at the initial period. Further in-situ FTIR spectra showed the band intensity of edge N H increases as the adsorption proceeds at 50°С but it decreases as the temperature rise to 200°С, in combined with the shift of C O adsorption peak, a intermolecular hydrogen bond between edge N H and the terminal C O group was suggested, which account for the better selectivity to C O than C C.

Biochar has been extensively used in ferrous metallurgy in recent years as it has comparable metallurgical properties to coke and coal, showing great potential for reduction of the production cost of iron and steel with enhanced quality and for promotion of environmental protection. This article reviewed the main applications of biochar in the iron and steel industry, including its use in coking, iron ore sintering, production of metallized pellets, blast furnace ironmaking, and electric arc furnace steelmaking. The challenges of using biochar and corresponding promising measures were also discussed for sustainable development of the industry.