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Resins (732-type), abundant and inexpensive resources were used to prepare porous carbon with small mesopores (CSM) by carbonization and post-chemical-activation with potassium hydroxide (KOH). The N 2 adsorption measurements revealed that CSM had high surface areas (1776.5 m 2 g −1 ), large pore volumes (1.10 cm 3 g −1 ), and nearly optimal narrow small mesopore sizes ranging from 2 to 7 nm. CSM was used as adsorbent to investigate the adsorption behavior for Rhodamine B (RhB). Due to the optimal pore size distributions (PSD), intensive-stacking interaction, S-doped, and electrostatic attraction, the CSM exhibited an ultra-high-capacity of 1590 mg g −1 for RhB in aqueous solutions. [ABSTRACT FROM AUTHOR]

[Display omitted] Developing efficient heterogeneous catalysts for the aerobic oxidation of C–H bonds using oxygen molecule as an oxidant to produce value–added aryl ketones is a challenging task. In this study, a series of cementite–iron–carbon composites (referred to as Fe–C–T, where T represents the pyrolysis temperature) were synthesized using a metal–organic–framework–mediated sacrificial template strategy. The Fe–C–T composites consist of highly dispersed Fe/(Fe 3 C or Fe 2 O 3) nanoparticles surrounded by graphitic carbon on porous carbon supports. Under mild reaction conditions (1 atm of O 2 pressure, 353 K, 12 h), with tert–butyl hydroperoxide (0.25 equiv.) as the initiator in a green solvent water, the prepared Fe–C–973 achieved a high conversion of 98.4 % for ethylbenzene and a selectivity of 98.7 % for acetophenone. This performance was markedly superior to the comparable Fe–C–873 and Fe–C–1073, as well as the commercially available Fe–based catalysts. Kinetic studies revealed that the catalytic system followed first–order kinetics for the substrate ethylbenzene, and the activation energy over Fe–C–973 was remarkably low of 40.4 kJ/mol. The highly distributed Fe 3 C nanoparticles embedded in the porous carbon framework were identified as the most active sites for the reaction. [ABSTRACT FROM AUTHOR]

G max : The highest reaction potential energy in the reaction path. [Display omitted] • Influence of Pt on the electronic properties of α-MoC-111 surface. • Inhibition effect of Pt on carbon deposition in WGS reaction. • Preventing surface oxidation by introducing Pt in α-MoC during WGS reaction. • Role of Pt in facilitating water dissociation. Pt/α-MoC is an outstanding catalyst for the low-temperature water gas shift (WGS, CO + H 2 O → H 2 + CO 2) reaction, exhibiting elevated activity, stability, and selectivity. In this study, three significant active site models (α-MoC-111, Pt-111, and Pt 1 /α-MoC-111) in Pt/α-MoC catalyst were established to investigate the promotion effect of Pt on the WGS reaction catalyzed by Pt/α-MoC. The results indicate that a synergistic effect at the metal-carbide interface enhances chemical activity compared to pure Pt-111 and α-MoC-111. Firstly, the surface of Pt 1 /α-MoC-111 exhibits strong metal-support interaction between Pt single atom and α-MoC-111 surface. Compared to the α-MoC-111 surface, the introduction of Pt strengthens the Mo−Mo bond while weakening the Mo−C bond. Secondly, adding a Pt atom significantly increases adsorption strength for CO and H 2 O, while decreasing it for products (CO 2), oxides (O atom), and by-products (C atom). The advantage of suppressing surface carbon deposition and oxidation is observed on the surface of Pt 1 /α-MoC-111. Furthermore, elementary reactions from the three mainstream reaction pathways of the WGS reaction are systematically calculated to evaluate catalytic performance among these three active sites. On the Pt 1 /α-MoC-111 surface, activation energy barriers for H 2 O dissociation and CO oxidation are reduced. This provides theoretical ideas for designing high-efficiency α-MoC based catalysts in the future. [ABSTRACT FROM AUTHOR]

Understanding the synergy between metal and zeolite for catalytic aquathermolysis harbours tremendous scientific and industrial importance. Herein, HZSM-5 is used as a model zeolite due to uniform physico-chemical structure, which is required to elucidate the intrinsic structure-performance relationship. We first devise a novel and scalable strategy to synthesize recyclable magnetic Fe 3 O 4 /HZSM-5 catalyst, which shows enhanced catalytic aquathermolysis performance compared to pure HZSM-5 catalyst. Moreover, the underlying synergy effect is then systematically elucidated by multi-techniques such as 1 H NMR, HRTEM, Py-IR, NH 3 -TPD, SARA and EL. Importantly, it is found that the change of acidity is not the dominating reason for enhanced performance. The synergy not only favors dispersion of Fe 3 O 4 nanoparticles on zeolite, but also effectively breaks C S bond and reduces the percentages of resin and asphaltene. Furthermore, the designed Fe 3 O 4 /zeolite catalyst effectively reduces the viscosity of heavy crude oil by 85.0%. This work sheds new light on the design of highly efficient heterogeneous catalysts for catalytic aquathermolysis. [ABSTRACT FROM AUTHOR]

• CH 4 direct dehydrogenation is preferred on Ni. • OH-assisted dehydrogenation of CH 4 is favored on Pt and Ni@Pt. • CO 2 direct dissociation is more favorable than H-assisted way on Ni. • H-assisted CO 2 dissociation is the dominant way on Pt and Ni@Pt. CO 2 reforming of methane (DRM) is a promising reaction for the carbon cycle in nature. Ni was found to be active in this process. However, single component Ni catalysts cannot meet the stability, activity and selectivity demands simultaneously. This paper presents a systematical density functional theory study to investigate the catalytic performance of Ni@Pt(1 1 1) core-shell surface compared with Ni(1 1 1) and Pt(1 1 1) in methane dry reforming. Two ways of O* and OH* assisted CH 4 dehydrogenation are considered in present work. CH 4 direct dissociation is more favored on Ni, while OH*-assisted CH 4 dehydrogenation is more competitive to proceed on Pt and Ni@Pt compared with direct way. Furthermore, Ni@Pt provides much less energy-demanding pathways for both CH and C oxidation, under the assistance of O* or OH*. Therefore, CH is much easier to be oxidized rather than decomposition into carbon on this surface, meanwhile, it is beneficial for carbon elimination and shows promising anti-carbon formation performance. Finally, free energy profiles are plotted at 1000 K and dominant reaction mechanisms of DRM conditions are proposed on three surfaces, respectively. On Ni(1 1 1), O* generated from CO 2 direct dissociation could provide dominant oxidant for CH* oxidation, while on Pt(1 1 1) and Ni@Pt, OH* originated from CO 2 H-assisted dissociation acted as the major oxidant for CH* oxidation. This work sheds some light on dominant reaction pathway and surface carbon formation, which could provide new mechanistic insight into CO 2 reforming methane on Ni-core/Pt-shell surface. [ABSTRACT FROM AUTHOR]

In this paper, we present a technique to fabricate normally off GaN-based high-electron mobility transistor (HEMT) by sputtering and post-annealing p -NiO x capping layer. The p -NiO x layer is produced by sputtering at room temperature and post-annealing at 500 °C for 30 min in pure O 2 environment to achieve high hole concentration. The V th shifts from −3 V in the conventional transistor to 0.33 V, and on/off current ratio became 10 7 . The forward and reverse gate breakdown increase from 3.5 V and −78 V to 10 V and −198 V, respectively. The reverse gate leakage current is 10 −9 A/mm, and the off-state drain-leakage current is 10 −8 A/mm. The V th hysteresis is extremely small at about 33 mV. We also investigate the mechanism that increases hole concentration of p -NiO x after annealing in oxygen environment resulted from the change of Ni 2+ to Ni 3+ and the surge of (111)-orientation. [ABSTRACT FROM AUTHOR]

Abstract: Core–shell structured ZnO/In2O3 composites were successfully synthesized via situ growth method. Phase structure, morphology, microstructure and property of the products were investigated by X-ray diffraction (XRD), TG-DTA, field emission scanning electron microscopy (FESEM), energy-dispersive spectrometry (EDS), transmission electron microscope (TEM) and photoluminescence (PL). Results show that the core–shell structures consist of spindle-like ZnO with about 800nm in length and 200nm in diameter, and In2O3 particles with a diameter of 50nm coated on the surface of ZnO uniformly. HMTA plays an important role in the formation of core–shell structures and the addition of In2O3 has a great effect on PL spectrum. Possible mechanism for the formation of core–shell structures is also proposed in this paper. [Copyright &y& Elsevier]

Abstract: Spindle-like ZnO nanostructures were successfully synthesized through direct precipitation of zinc acetate aqueous solution at 60°C. Phase structure, morphology and microstructure of the products were investigated by X-ray diffraction, TG-DTA, FTIR and field emission scanning electron microscopy (FESEM). Result showed that hexagonal wurtzite structure ZnO nanostructures with about 100nm in diameter and 100–200nm in length were obtained. HMTA acted as a soft template in the process and played an important role in the formation of spindle-like ZnO nanostructures. Meanwhile, different morphologies were also obtained by altering synthetic temperature, additional agents and the ratios of Zn2+/OH−. Possible mechanism for the variations of morphology with synthesis parameters was also discussed in this paper. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fe/Fe 3 C@NC hybrids fabricated by carbonization of NH 2 –MIL–101(Fe) octahedrons. • Fe/Fe 3 C@NC had large surface area, hierarchical pore structure, unique composition. • Fe/Fe 3 C@NC–750 exhibited best performance with tolerance to functional groups. • Direct and condensation routes were involved in catalytic transfer hydrogenation. Owing to the competitive hydrogenation of reducible functionalized groups and the complexity of the reaction mechanism, the selective catalytic hydrogenation of nitroarene compounds to value-added amine products is challenging. Herein, we designed and prepared a series of highly efficient iron-based nanocomposites (Fe/Fe 3 C@NC–T) via direct pyrolysis of the presynthesized NH 2 –MIL–101(Fe) octahedrons under nitrogen atmosphere, wherein tiny metallic Fe/Fe 3 C nanoparticles (NPs) were homogeneously inlaid in the N-doped porous carbon matrix. Among the various derived catalysts, Fe/Fe 3 C@NC–750 exhibited the best performance, with good tolerance to several different functional groups for the catalytic transfer hydrogenation of nitroarenes to anilines using N 2 H 4 ·H 2 O as the reductant under mild conditions. This performance was also superior to those of commercial catalysts (Fe, Fe 2 O 3 , and Fe 3 C) and Fe/Fe 3 C@C–750 without N doping. The synergistic catalysis between the Fe-based NP and N dopant mainly contributed to the excellent catalytic performance of Fe/Fe 3 C@NC–750. Moreover, the mechanism study revealed that both the direct route and the condensation route were involved in this catalytic reaction system. [ABSTRACT FROM AUTHOR]

Abstract: Arrays of conical-like spikes can be formed on silicon surface after irradiated with femtosecond laser pulses in ambient of SF6 or N2. In this article, we report our observations on how the shape of the spikes formed on silicon surface varies with the polarization of laser beam. The experimental results show that, with circular polarized laser irradiation, the shape of the spikes is conical; however, with linearly polarized laser irradiation, the spikes show elliptic conical shape, and the long-axes are perpendicular to the direction of the polarization of laser beam. The asymmetric shape of spikes produced by linearly polarized laser beam can be explained by considering the polarization dependence of Fresnel-refraction. [Copyright &y& Elsevier]

TEM image of 3D pomegranate-like core@shell porous carbon structure and their comparison figure with the previous reported capacitance values of porous carbon materials. • A functionalized N and O co-doped three-dimensional hierarchical pomegranate-like porous carbon was rationally synthesized. • The hierarchical porous structure, high packing density and enriched N and O functional groups are crucial. • The symmetric suporcapacitor with the pomegranate-like porous carbon boots a high gravimetric (volumetric) energy density. Recently, the heteroatom-enriched porous carbons have received considerable attention on the research of electrodes with high gravimetric capacitances for supercapacitors (SCs). However, their relatively low volumetric capacitances have limited their practical applications due to very low packing density and poor ion diffusion at high mass loadings. In this study, by means of a facile modified chemical activation route, a functionalized N and O co-doped three-dimensional (3D) hierarchical pomegranate-like porous carbon (PPC) was rationally synthesized. First, A core–shell structured precursor composite for PPC was constructed. The polypyrrole (PPy) with the desired functional group was adopted as the precursor of the pomegranate-like core, and the polyacrylamide (PAM) hydrogel as the precursor of the pomegranate-like shell (designated as PPy/PAM). Then, after calcination of the PPy/PAM hydrogel precursor composites, a novel 3D hierarchical PPC was achieved. The as-obtained PPC offers short diffusion paths of ions, increases packing density and provides abundant active sites for pseudocapacitance by increasing self-oxygen–nitrogen-doped content. The performance tests of SC with PPC manifest that at 156 W kg−1 (109.7 W L-1), boosted energy density of 11.5 Wh kg−1 (8.05 Wh L-1) can be achieved. The as-obtained PPC is the promising electrode material of high-performance SCs for practical applications. [ABSTRACT FROM AUTHOR]

• Ag/ND/g-C 3 N 4 photocatalyst was synthesized for the first time. • Ag/ND/g-C 3 N 4 showed enhanced photocatalytic activity both in H 2 evolution from water splitting and degradation of organic pollution. • The Ag/ND/g-C 3 N 4 exhibited good photostability after four-run test. • The photocatalytic reaction mechanism was illustrated in detail. Efficient separation of photogenerated carriers and light harvesting are the two key factors for high photocatalytic performance. In this work, a novel double-heterojunction silver/nanodiamond/graphite-carbon nitride (Ag/ND/g-C 3 N 4) structured photocatalyst has been synthesized. In comparison to single-heterojunction Ag/g-C 3 N 4 , the double-heterojunction Ag/ND/g-C 3 N 4 photocatalyst presents with a 4.9-times enhancement in H 2 evolution from water splitting and 2.4-times promotion in degrading organic pollution under visible-light irradiation. Furthermore, the Ag/ND/g-C 3 N 4 exhibits good photostability after four-run test. The enhanced photocatalytic activity can be attributed to the synergetic effect of surface plasmon resonance from Ag, optical confinement from ND and suitable band alignment in the double-heterojunction structure, which boost the light absorption capacity and increase the photogenerated charge separation of g-C 3 N 4. This study provides a reference for the development of efficient carbon based photocatalysts, which can be used not only for the production of H 2 from water splitting, but also for the photodegradation of pollutants under visible light irradiation. [ABSTRACT FROM AUTHOR]

• The reaction mechanisms of each step evolve with the surface Cl/Cu ratios. • The origin of the K effect was explored by Van-der-Waals corrected DFT calculations. • Free energy analysis is consistent with the experimental observation. • KCl modifies the electronic structure of the surface. Potassium promoters are widely used in industrial catalysts of ethylene oxychlorination to achieve optimum performance. However, the origin of the promoter effect is not fully understood. Herein, we investigated the potassium promotion effect on CuCl 2 /γ-Al 2 O 3 catalyzed ethylene oxychlorination by kinetic experiments and DFT calculations. Kinetic experiments observed the effect of KCl on individual steps, and the evolution of the reaction mechanisms with Cl/Cu ratios. Further exploration via DFT found that KCl increases the formation energy of Cl vacancy (Δ E v) and thus inhibits the reduction activity, which is attributed to the shift-down of Bader charge of Cl. Δ E v boosts with the decline of Cl/Cu ratios; thus, ethylene can extract Cl atoms from the surface with a Cl/Cu ratio of 2, while it anchors to metal atoms at lower Cl/Cu ratios. The distinct adsorption modes reflect the evolution of reaction mechanisms with Cl/Cu ratios. KCl facilitates the adsorption of oxygen owing to the shift-up of the Bader charge of Cu atom. Potassium reduces the Gibbs free energy barrier of the oxidation step, which agrees with the experimental observation. It is concluded that the potassium promoter effect on the catalytic performance mainly results from the modification of the charge of surface atoms. [ABSTRACT FROM AUTHOR]