The desulfurization activity and selective hydrogenation of Cu/ZnO adsorbents on the different polarity ratios of ZnO as supports was investigated in reactive adsorption desulfurization. The ZnO particles were synthesized by the hydrothermal process, and CuO/ZnO adsorbents were synthesized by incipient impregnation method. The structure and morphology of the ZnO and CuO/ZnO were characterized by X-ray diffraction (XRD), N2 adsorption–desorption, X-ray photoelectron spectra (XPS), scanning electron microscope/selected area electron diffraction (SEM/SAED), transmission electron microscopy (TEM), and temperature-programmed reduction (TPR). The surface area and polarity ratio of ZnO supports were controlled by the calcination temperature and concentration of P123, respectively. More reactive activity sites were provided by the high surface area of ZnO supports, thus improving the desulfurization activity. The polarity ratio of ZnO may strongly influence the hydrogenation reactions of olefins. The selective hydrogenation increased with the value of polarity ratios.

Many strategies, such as doping metal, designing low-dimensional nanostructures, and enhancing the utilization of active sites based on a conductive support, have been intensively pursued to improve the intrinsic activity of transition metal chalcogenides for the hydrogen evolution reaction (HER). However, integrating all the above-mentioned merits into one electrocatalyst is still a significant challenge. Herein, we have successfully prepared uniform CoMoS/CoMoO4 (CMS) shell–core nanorods, with a diameter of 60 nm and a length of 800 nm, supported on N-doped reduced graphene oxide (NRGO). The obtained CMS/NRGO can combine many advantages, including transition metal doping, one-dimensional nanorods, and the superior conductivity of NRGO, resulting in very promising HER properties and excellent stability. The optimum sulfurization temperature for unsupported CMS nanorods has been explored using uniform CoMoO4 nanorods as a precursor. Although CMS-3 prepared with a sulfurization temperature of 300 °C has been found to possess the optimum activity for the HER, when adopting NRGO as a support, CMS-3/NRGO exhibits an impressive enhancement in HER performances with a low overpotential of 80 mV, a small Tafel slope of 58 mV dec−1, and a large exchange current density of 428 μA cm−2. In addition, the electrocatalytic activity of CMS-3/NRGO shows a negligible delay after 1000 cycles, indicating its robust electrochemical stability in acid electrolyte solution. Therefore, adopting low-temperature sulfurization of one-dimensional metal oxide precursors supported on NRGO may be a promising strategy for obtaining excellent electrocatalysts for the HER.

•Ternary CoS2/MoS2/RGO with CoMoS phase as electrocatalyst for HER was prepared.•CoMoS phase have the metallic nature and highly intrinsic activity for HER.•RGO support ensures good distribution of CoMoS phase and enhances the conductivity.•The introduction of CoMoS and RGO may be a novel strategy for efficient HER of MoS2.CoMoS phase with metallic character plays crucial role on enhancing the activity of MoS2 electrocatalysts for hydrogen evolution reaction (HER). However, only Co atoms located in the edges of MoS2 can create CoMoS phase, so it is a challenge to obtain CoMoS phase with homogeneous distribution limited by the layered MoS2 and doping method of Co. Herein, we reported a simple one-pot hydrothermal method to prepare novel ternary CoS2/MoS2/RGO with CoMoS phase for HER using reduced graphene oxide (RGO) as support. XPS proves the formation of CoMoS phase, implying the enhanced activity for HER. RGO support ensures the well distribution of CoMoS phase and enhances the conductivity of CoS2/MoS2/RGO. Compared to CoS2/RGO, MoS2/RGO and CoS2/MoS2, the obtained CoS2/MoS2/RGO shows superior activity for HER with an onset overpotential of −80 mV (vs. RHE), small Tafel slope of 56 mV dec−1, high exchange current density of 11.4 μA cm−2 and rigid electrochemical durability. The enhanced performances for HER may be ascribed to the formation of CoMoS phase with high activity and the existence of RGO support with good electrical conductivitys in ternary CoS2/MoS2/RGO. Therefore, the introduction of CoMoS phase and RGO into MoS2 could effectively enhance electrocatalytic properties for HER.Download high-res image (133KB)Download full-size image

•Bimetallic Ni-Cu/SAPO-11 catalysts were prepared by co-impregnation method.•n-Octane hydroisomerization over monometallic Ni/SAPO-11 and bimetallic Ni-Cu/SAPO-11 were compared.•Copper changed the electronic interaction of nickel and diluted the nickel ensemble size in the Ni-Cu alloy.•The hydrogenolysis reaction was effectively restrained over the bimetallic Ni-Cu/SAPO-11 catalysts.Bimetallic Ni-Cu/SAPO-11 catalysts were prepared by co-impregnation method and assessed in the hydroisomerization of n-octane. Their physicochemical properties were characterized by means of powder X-ray diffraction, nitrogen adsorption-desorption, temperature-programmed desorption of ammonia, pyridine-adsorbed infrared spectroscopy, temperature-programmed reduction of hydrogen, transmission electron microscopy, energy dispersive X-ray, and X-ray photoelectron spectroscopy. The Ni-Cu alloy was formed after reduction in the H2 flow at 450 °C. Copper changed the electronic interaction of nickel and diluted the nickel ensemble size in the Ni-Cu alloy. The hydrogenolysis reaction that decreases the selectivity of isomerization was effectively restrained over the bimetallic Ni-Cu/SAPO-11 catalysts. The selectivity to n-octane isomers over the bimetallic nickel (3%) and copper (1.5%) catalyst was 19% more than that over the monometallic nickel (3%) catalyst at the conversion of 70%. A possible reaction scheme was proposed to explain the catalytic properties in n-octane hydroisomerization.Download high-res image (233KB)Download full-size image

Cobalt phosphides have been used as promising electrocatalysts for catalyzing the hydrogen evolution reaction (HER) in acidic aqueous solutions. In order to further explore the influence of phase structure and support effect on the catalytic activity for HER, herein, a series of cobalt phosphide-based electrocatalysts, including Co2P, CoP, Co2P/CNTs, CoP/CNTs, Co2P/NCNTs and CoP/NCNTs, were synthesized successfully via a facile thermal decomposition approach. The crystalline phase can be controlled by changing the phosphide source species. When the phosphide source was trioctylphosphine, CoP-based catalysts were obtained. However, Co2P-based catalysts can be obtained by using triphenylphosphine as the phosphide source. Then the phase catalytic activity and stability of the as-synthesized cobalt phosphide-based catalysts for hydrogen evolution were compared. The results show that the catalytic activity followed the order CoP/NCNTs > Co2P/NCNTs > CoP/CNTs > Co2P/CNTs > CoP > Co2P, which can be attributed to the different atomic ratios of Co to P, the strong interaction between cobalt phosphide and carbon species and the doping of N atoms into CNTs. Our studies indicate that the HER catalytic efficiency of transition metal phosphide catalysts can be improved significantly by adjusting active phase and carbon species structures.

The enhancement of catalytic performance of cobalt phosphide-based catalysts for the hydrogen evolution reaction (HER) is still challenging. In this work, the doping effect of some transition metal (M = Fe, Ni, Cu) on the electrocatalytic performance of the M–Co2P/NCNTs (NCNTs, nitrogen-doped carbon nanotubes) hybrid catalysts for the HER was studied systematically. The M–Co2P/NCNTs hybrid catalysts were synthesized via a simple in situ thermal decomposition process. A series of techniques, including X-ray diffraction, X-ray photoelectron spectroscopy, inductively coupled plasma-optical emission spectrometry, transmission electron microscopy, and N2 sorption were used to characterize the as-synthesized M–Co2P/NCNTs hybrid catalysts. Electrochemical measurements showed the catalytic performance according to the following order of Fe–Co2P/NCNTs > Ni–Co2P/NCNTs > Cu–Co2P/NCNTs, which can be ascribed to the difference of structure, morphology, and electronic property after doping. The doping of Fe atoms promote the growth of the [111] crystal plane, resulting in a large specific area and exposing more catalytic active sites. Meanwhile, the Feδ+ has the highest positive charge among all the M–Co2P/NCNTs hybrid catalysts after doping. All these changes can be used to contribute the highest electrocatalytic activity of the Fe–Co2P/NCNTs hybrid catalyst for HER. Furthermore, an optimal HER electrocatalytic activity was obtained by adjusting the doping ratio of Fe atoms. Our current research indicates that the doping of metal is also an important strategy to improve the electrocatalytic activity for the HER.

A novel and highly active hybrid catalyst for the hydrogen evolution reaction (HER) is constructed by the in situ growth of CoP on the surface of MoS2 and CNTs. The CoP/MoS2-CNTs hybrid catalyst exhibits Pt-like catalytic activity for the HER with an overpotential close to zero, a Tafel slope of 42 mV dec−1 and good stability, which is the best among all non-noble metal catalysts.

•Novel MoS2/C-doped MoO2 nanobelts for HER have been successfully synthesized.•MoO2 nanobelts may reduce stacking of MoS2 nanosheets and improve conductivity.•Sulfidizing MoOx-based nanostructures may be an efficient way for electrocatalysts.As efficient electrocatalysts for hydrogen evolution reaction (HER), novel MoS2/carbon-doped molybdenum dioxide (MoS2/C-doped MoO2) nanobelts have been successfully synthesized via sulfuration treatment of the C-doped MoO2 nanobelts. Mo3O10(C6H8N)2•2H2O with one-dimensional structure, high conductivity and large surface area has been used as template to produce C-doped MoO2 nanobelts. After the sulfuration treatment, MoS2 nanosheets vertically grow along the axis direction of conducting C-doped MoO2 nanobelts leading to less stacking of MoS2 nanosheets and improved conductivity. The as-prepared MoS2/C-doped MoO2 nanobelts have been examined by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX) and X-ray photoelectron spectroscopy (XPS). The growth mechanism of MoS2/C-doped MoO2 nanobelts has been discussed. The MoS2/C-doped MoO2 nanobelts exhibit excellent HER activity with the low onset overpotential of 120 mV (vs. RHE) and a small Tafel slope of 55 mV dec−1. The sulfuration treatment of C-doped MoO2 nanobelts could improve the conductivity and decrease the stacking of MoS2 nanosheets, which could provide more exposed active sites and faster rate of electron transfer, thus their electrocatalytic performances for HER have been enhanced drastically. The sulfuration treatment of unique MoOx-based nanostructures may be a potential and efficient strategy to manufacture efficient MoS2-based electrocatalysts for HER.

•Reduced Co3O4 (RCo3O4) was synthesized by a facile NaBH4 reduction treatment.•RCo3O4 has the enhanced OER activity owing the increasing of oxygen vacancies.•Increasing oxygen vacancy provides a new way to prepare efficient electrocatalyst.Novel reduced Co3O4 nanoparticles as electrocatalyst have been synthesized by a facile NaBH4 reduction treatment. Microwave-assisted Co3(CH3COO)5(OH) has been used as precursor to increase the surface area of Co3O4. The as-prepared samples were characterized by X-ray diffraction (XRD), Transmission electron microscope (TEM) and scanning electron microscope (SEM). The original Co3O4 (OCo3O4) nanoparticles have been prepared by annealing of Co3(CH3COO)5(OH). After treatment by NaBH4, OCo3O4 transforms into the reduced Co3O4 (RCo3O4). Electrochemical measurements for oxygen evolution reaction (OER) show that RCo3O4 has more excellent electrocatalytic activity with the lower onset potential of 1.5 V (vs. RHE) and larger current density by over 6.4 times than that of OCo3O4, which may be ascribed to the more oxygen vacancies derived from reduction treatment of NaBH4. Therefore, increasing the number of oxygen vacancies of metal oxides by facile reduction treatment may be a promising way to prepare the efficient electrocatalysts for OER.

Designing efficient, stable and inexpensive electrocatalysts to replace Pt-based catalysts for the hydrogen evolution reaction (HER) is highly desired in renewable energy research. In this study, we report the synthesis of nickel phosphide nanoparticles decorated on multiwalled carbon nanotubes (Ni2P/CNT) by in situ thermal decomposition of nickel acetylacetonate as a nickel source and trioctylphosphine as a phosphorus source in oleylamine solution of CNT. As a novel HER electrocatalyst, the Ni2P/CNT nanohybrid exhibits excellent electrocatalytic activity in 0.5 M H2SO4 with a low onset overpotential (88 mV), a small Tafel slope (53 mV dec−1), a high exchange current density (0.0537 mA cm−2) and good stability. It only needs overpotentials of 98 and 124 mV to attain current densities of 2 and 10 mA cm−2, respectively. In addition, the Ni2P/CNT nanohybrid shows nearly 100% Faradaic efficiency in acid solutions. This work successfully demonstrates that the introduction of Ni2P NPs into CNT for enhanced electrocatalytic properties is feasible, and that this may open up a potential way for designing more efficient Ni2P-based catalysts for the HER.

Monodispersed nickel phosphide nanocrystals (NCs) with different phases (Ni12P5, Ni2P and Ni5P4) were synthesized via the thermal decomposition approach using nickel acetylacetonate as the nickel source, trioctylphosphine as the phosphorus source and oleylamine in 1-octadecene as the reductant. The phases of the as-synthesized nickel phosphide NCs could easily be controlled by changing the P:Ni precursor ratio. The structure and morphology of the as-synthesized nickel phosphide NCs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and N2 adsorption–desorption. A formation mechanism for the as-synthesized nickel phosphide NCs was proposed. We further studied the influence of the phase of the nickel phosphide NCs on the electrocatalytic properties for the hydrogen evolution reaction (HER). All phases showed good catalytic properties, and the Ni5P4 NCs with a solid structure exhibited higher catalytic activity than the Ni12P5 and Ni2P NCs. This superior catalytic activity is attributed to the higher positive charge of Ni and a stronger ensemble effect of P in Ni5P4 NCs. This study demonstrates that the crystalline phase is important for affecting the electrocatalytic properties.

•Ni2P/NRGO hybrid catalyst was synthesized via thermal decomposition approach.•Ni2P/NRGO hybrid shows high activity and stability for HER.•Ni2P/NRGO hybrid exhibits higher catalytic activity than Ni2P/RGO hybrid.•Strong interaction between Ni2P and NRGO enhances the activity and stability.•This study offers a new strategy for improving the catalytic activity for HER.Development of hybrid catalysts with high activity, good stability and low cost is extremely desirable for hydrogen production by electrolysis of water. In this work, a hybrid composed of Ni2P nanoparticles (NPs) on N-doped reduced graphene oxide (NRGO) is synthesized via an in situ thermal decomposition approach for the first time and investigated as a catalyst for the hydrogen evolution reaction (HER). The as-synthesized Ni2P/NRGO hybrid exhibits an enhanced catalytic activity with low onset overpotential (37 mV), a small Tafel slope (59 mV dec−1), a much larger exchange current density (4.9 × 10−5 A cm−2), and lower HER activation energy (46.9 kJ mol−1) than Ni2P/RGO hybrid. In addition, the Ni2P/NRGO hybrid maintains its catalytic activity for at least 60′000 s in acidic media. The enhanced catalytic activity is attributed to the synergistic effect of N-doped RGO and Ni2P NPs, the charged natures of Ni and P, as well as the high electrical conductivity of Ni2P/NRGO hybrid. This study may offer a new strategy for improving the electrocatalytic activity for hydrogen production.

•Nanostructured nickel phosphides supported on carbon nanospheres (CNSs) have been synthesized for the first time.•The Ni2P/CNSs-x hybrids exhibit excellent activity and stability for the HER.•The Ni2P/CNSs-x hybrids exhibit higher catalytic activity than the Ni/CNSs hybrid.•The Ni2P/CNSs-x hybrids can be a promising candidate for substituting noble metal catalyst.New electrocatalysts to replace noble metal catalysts for the hydrogen evolution reaction (HER) are highly desired to produce renewable and environmentally-friendly energy. In this work, nanostructured nickel phosphides supported on carbon nanospheres (CNSs) with different carbon content (Ni2P/CNSs-x, x = 10, 20, 40, 60) are synthesized by thermal decomposition using nickel acetylacetonate as nickel source and trioctylphosphine as phosphorus source in an oleylamine solution containing CNSs for the first time. The structure and morphology are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), and N2 adsorption-desorption. Then the electrocatalytic properties of as-synthesized Ni2P/CNSs-x for the HER are studied. In addition, the Ni/CNSs-20 hybrid is synthesized and the electrocatalytic properties are studied. The results show that all the Ni2P/CNSs hybrids exhibit higher catalytic activity than the Ni/CNSs-20 hybrid. The catalytic activity of the as-synthesized Ni2P/CNSs hybrid can be enhanced by changing the carbon content. The superior catalytic activity is attributed to the coupling effect between the Ni2P nanoparticles and CNSs, the electronic effect of Ni, the ensemble effect of P, the large surface area, and the high electron conductivity of CNSs. This study paves the way for the design of HER electrocatalysts with high performance and low-cost that can be employed under acid conditions.

The geometrical and electronic structures and photocatalytic performance of subnanometer Agn clusters (n = 2–6) deposited on AgBr(110) are studied under the framework of density functional theory (DFT) plus Hubbard U contributions. The most stable adsorption is facilitated by AgBr(110) interacting with the most stable structure of Agn and results in a new metal-induced gap band (MIGB) located between the valence (VB) and the conduction bands (CB). Both the MIGB and CB are mainly contributed by the sp hybridization states from the metal clusters, while the VB is composed primarily of the 4p states of the surface Br and the 4d states of Ag from both the adsorbate and the surface. The variety of the electronic structures favors visible and infrared light absorption, which strengthens substantially as the cluster size is enlarged. The dominant localization of the photo-excited electrons on the Agn clusters facilitates the oxidation–reduction reactions occurring on the surface and reduces effectively the photolysis of AgBr under sunlight irradiation. The overpotentials of the CB and VB edges indicate that photocatalytic conversion of CO2 with H2O to methanol is possible on AgBr(110) deposited with the Agn clusters which has been realized experimentally.

In this paper, an efficient method to fabricate Al-based metal organic framework (Al-MOF) MIL-96 crystals with controllable size and morphology, by mixing other forms of reactants to replace the coordination modulators or capping agents, is presented. The size and morphology of the MIL-96 crystals can be selectively varied by simply altering the ratio of dual reactants via their hydrolysis reaction. All the samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) and nitrogen sorption. Then based on the BFDH theory, a mechanism for the impact of hydrolysis of reactants on the crystal size and morphology is presented and discussed. We also evaluated the performance of these MOFs as sorbents for capturing CO2, and they all show enhanced adsorption properties compared with the bulk material, displaying high adsorption capacities on CO2 at atmospheric pressure and ambient temperature.

An efficient method was developed for the synthesis of nickel phosphide nanocrystals (NCs) via thermal decomposition of bis(triphenylphosphine)nickel dichloride (BTND) precursor in the presence of oleylamine (OAm) for the first time. The effect of synthetic conditions such as reaction temperature, reaction time and OAm quantity on the size and phase of the as-synthesized nickel phosphide NCs was discussed. The structure and morphology were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and N2 adsorption–desorption measurements. The results showed that the size of Ni2P NCs can be controlled by increasing reaction temperature and OAm quantity. The phase of nickel phosphide NCs can be controlled by changing the reaction time. The shorter reaction time was beneficial for forming Ni12P5 NCs, and longer reaction time was beneficial for forming Ni2P NCs. Furthermore, a possible growth mechanism of the as-synthesized nickel phosphide NCs was proposed. These synthetic techniques may be expanded to other metal phosphide materials.

Mesoporous alumina with different morphologies was synthesized via thermal decomposition of the Al-based metal–organic frameworks (Al-MOFs) MIL-110 and MIL-100, in which Al-MOFs were used as the Al source and precursor. The hexagon rod-shaped and octahedron-shaped alumina products with morphology retained from their precursors were obtained and characterized. The results show that the construction of Al-MOFs, especially the aluminium building units plays a key role in the textural structure of the obtained alumina products. Besides, the differences in textural properties as well as the possible formation mechanism of the final alumina products are well explained by taking into account thermal behaviour and intrinsic structure features, especially the aluminium building units, of the Al-MOFs precursors. This work presents an easy new method to produce alumina with tailored morphology, tunable texture and microstructure, which is also an operational method fit for other metal oxide materials.

Nanostructured nickel sulfide with different phases was synthesized via a thermal decomposition approach using nickel acetylacetonate as the nickel source, 1-dodecanethiol as the sulfur source and oleylamine as the high boiling solvent. The phase evolution of nickel sulfide nanocrystals (NCs) can be easily achieved by changing the molar ratio of Ni:S precursor and the species of the solvent. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) mapping, X-ray photoelectron spectroscopy (XPS) and N2 adsorption–desorption were used to characterize the as-synthesized nickel sulfide NCs. The electrocatalytic activity and stability of the as-synthesized nickel sulfide NCs for the hydrogen evolution reaction (HER) were investigated. Due to the different crystalline phase structures of the as-synthesized nickel sulfide NCs, the β NiS NCs exhibit better electrocatalytic activity with a low onset overpotential (186 mV), a small Tafel slope (51.2 mV dec−1), a high exchange current density (2.4 × 10−6 A cm−2), a large electrochemical double-layer capacitance (2.7 mF cm−2) and improved stability than the Ni7S6 and α NiS + β NiS NCs for HER. This study provides a good strategy for designing more efficient nickel sulfide catalysts for the HER.

•Alumina was synthesized via direct thermal treatment of Al-based MOFs MIL-96.•Alumina with hexagonal spindle-shaped morphology was obtained.•The textural properties of alumina can be modulated by thermal treatment condition.•The effect of thermal treatment conditions on the textural properties and formation mechanism were discussed.•The effect of textural properties and inner structure on the adsorption ability of alumina were investigated.Hexagonal spindle-shaped mesoporous alumina with different internal structures were prepared using Al-based metal-organic frameworks MIL-96 as precursor through thermal treatment method. MIL-96 and alumina products were characterized by XRD, SEM, TEM, BET and TG. Results from these characterizations showed that alumina products keep the morphology of their precursor, and the thermal treatment conditions have large effect on alumina microstructures. The state of atmosphere and heating rate are the main factors affecting the internal textural properties of alumina. A possible transformation mechanism was also proposed. In addition, the effect of textural properties and structure on the adsorption ability of alumina was investigated. This work presents a novel method, which builds a direct linkage between MOF crystals and metal oxide microstructures, to control the morphology, structure and performance of alumina and other metal oxide materials.Hexagonal spindle-shaped alumina with different textural properties, which significantly affect the adsorption ability of alumina, were synthesized via direct thermal treatment of Al-based MOFs MIL-96.

The first POMos-based hybrid with penta-coordinated Mo in trigonal bipyramid geometry for Mo–O clusters has been hydrothermally synthesized and characterized by IR, TG, XPS, and X-ray diffraction analysis. Structure analysis indicated penta-coordinated together with tetra-coordinated Mo existed in the POMos-based hybrid. The hybrid was successfully used as an efficient precursor for a hydrodesulfurization (HDS) catalyst for the first time.

NiMo catalysts were prepared using Waugh-type NiMo heteropolycompounds as active phase precursors and evaluated in hydrodesulfurization (HDS) of dibenzothiophene (DBT). These catalysts were compared with corresponding reference catalysts prepared from the conventional precursors (ammonium heptamolybdate and nickel nitrate). Prepared catalysts were characterized by N2 physisorption, XRD, FT-IR, H2-TPR, DRIFT of CO adsorption and HRTEM techniques. It was found that NiMo catalysts prepared from Waugh-type NiMo HPCs showed higher performance in HDS of DBT than their counterparts. Possible reasons of this result were discussed.

A compound catalyst (RA) consisted of Ni, ZnO and HZSM-5 with functions of reactive adsorption desulfurization (RADS) and olefin aromatization for fluid catalytic cracking (FCC) gasoline upgrading was prepared. X-ray powder diffraction (XRD), temperature-programmed reduction and low-temperature N2 adsorption were used to characterize the properties of the catalysts. Performance evaluation by FCC gasoline was carried out, and the result showed that the catalyst RA performed well in desulfurization and aromatization. For comparison, RADS catalyst (represented by DS) consisted of Ni and ZnO and aromatization catalyst (represented by Ar) consisted of HZSM-5 were prepared, respectively. They were combined in different ways to help investigating interaction between Ni and HZSM-5. Performance evaluated by FCC gasoline showed that catalyst RA performed best in desulfurization with a slight octane number loss. Interaction between Ni and HZSM-5 is a significant factor which influences the performance of the catalyst.

Mesoporous boehmite with different morphologies have been prepared by a surfactant-free solvothermal technique with an alcohol-toluene mixed system, and the corresponding γ-Al2O3 was obtained after sequential calcination. The effects of the type of alcohol on the crystalline structure, textural properties, morphology, and acidity of the products were investigated through a series of characterizations, including XRD, SEM, TEM, nitrogen physisorption, 27Al MAS NMR, and Py-IR. The results indicate that alcohol molecules with different number of carbon atoms make a strong impact on the growth of boehmite crystallites and their sequent assemblies. Longer alkyl chain in the alcohol molecule is favorable for the formation of boehmite with hierarchical structures. The changes in crystalline structure further affect the pore structure and surface acidity of the alumina samples. Besides, different inorganic salts including Ca(NO3)2·4H2O, Cu(NO3)2·3H2O, Co(NO3)2·6H2O, MgCl2·6H2O, Zn(NO3)2·6H2O, and Fe(NO3)3·9H2O were used instead of Al(NO3)3·9H2O to synthesize the corresponding hydroxides, and the results show that other hydroxide hierarchical structures with similar morphologies can be also obtained through this simple solvothermal route.Graphical abstractHighlights► γ-Al2O3 hierarchical structure can be obtained under solvothermal condition. ► The physicochemical properties of γ-Al2O3 are dependent on the solvent. ► Pore structures are related to the crystallite size and morphology of γ-Al2O3. ► The behavior of solvent in the boehmite synthesis can be used to prepare other inorganic hierarchical structure.

In the absence of template and surfactant, hierarchical nanostructured boehmite was synthesized via a simple solvothermal route using aluminum nitrate as aluminum source and isopropanol–toluene mixture as solvent. The crystal structures, morphologies and textural properties of products were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM) and N2 adsorption–desorption technique. The as-obtained hierarchical nanostructures consist of nanosheets keeping Brunauer–Emmett–Teller (BET) specific surface area and pore volume of ca. 264.7 m2/g and 1.2 cm3/g, respectively. The experimental results show that the longer reaction time and the lower reaction temperature are unfavorable to the formation of hierarchical nanostructures. Moreover, the properties of solvent have important influence on the morphology of product. The possible formation mechanism of boehmite hierarchical nanostructures was proposed and discussed.Highlights► Hierarchical nanostructured boehmite assembled by nanosheets was prepared via a template free solvothermal route. ► Both long reaction time and high temperature promote the generation and growth of boehmite nanocrystallites. ► The relative large molecule size of alkyl alcohol is favor of separation of boehmite particles.

AbstractZnSi/HZSM-5 aromatization catalyst was prepared by modification with silicon on the outer surface and zinc on the inner surface; its aromatization performance and resistance to carbon deposition were investigated in a laboratory-fixed reactor with the full range FCC gasoline as the feed. The modification mechanism was also discussed. The crystal phase, pore structure, acidity of the modified catalysts and the coke formed during the reaction were characterized by means of XRD, BET surface area, Py-IR and elemental analyses. The modified ZnSi/HZSM-5 aromatization catalyst exhibits a superior activity, stability and performance in reducing olefin content of FCC gasoline; under the conditions of 500°C, 1.5 MPa and a space velocity of 3.0 h−1, the mass fractions of olefins and aromatics in the upgraded gasoline are 21.75% and 27.32%, respectively.

•S22− in MoS2 has been proved to be key factor for improving HER activity.•γ-Al2O3 template has been used to prepare MoS2 with S22− for enhanced HER.•The calcination temperature has important effect on the amount of S22− in MoS2.Owing to the real active sites for hydrogen evolution reaction (HER) located on the rims and edges, it is critical to expose maximum active sites by limiting the stacking of MoS2. On the other hand, the existence of disulfide ligand (S22−) in MoS2 has been proved to be another key factor determining the rate of HER. In this work, a facile γ-Al2O3 template-assisted synthesis has been conducted to prepare highly dispersed MoS2 with appropriate amount of terminal disulfide ligand (S22−) as efficient electrocatalysts for HER. γ-Al2O3 template can facilitate the highly-dispersed growth of MoS2 with small size, which can provide vast active sites for HER. The effect of the different calcination temperature at 300, 350, 400, 450 and 500 °C on the crystallinity and amount of terminal S22− of MoS2 samples has been investigated. After removing γ-Al2O3, MoS2-400 electrocatalyst has the best HER electrocatalystic performance with a low onset overpotential of 120 mV and small Tafel slope of 84 mV dec−1, maybe due to the moderate crystallinity of MoS2 and amount of terminal S22−. Therefore, γ-Al2O3 template synthesis at the optimum calcination temperature may be a promising method for transition metal sulfides as efficient electrocatalysts for HER.

Cobalt phosphides have been used as promising electrocatalysts for catalyzing the hydrogen evolution reaction (HER) in acidic aqueous solutions. In order to further explore the influence of phase structure and support effect on the catalytic activity for HER, herein, a series of cobalt phosphide-based electrocatalysts, including Co2P, CoP, Co2P/CNTs, CoP/CNTs, Co2P/NCNTs and CoP/NCNTs, were synthesized successfully via a facile thermal decomposition approach. The crystalline phase can be controlled by changing the phosphide source species. When the phosphide source was trioctylphosphine, CoP-based catalysts were obtained. However, Co2P-based catalysts can be obtained by using triphenylphosphine as the phosphide source. Then the phase catalytic activity and stability of the as-synthesized cobalt phosphide-based catalysts for hydrogen evolution were compared. The results show that the catalytic activity followed the order CoP/NCNTs > Co2P/NCNTs > CoP/CNTs > Co2P/CNTs > CoP > Co2P, which can be attributed to the different atomic ratios of Co to P, the strong interaction between cobalt phosphide and carbon species and the doping of N atoms into CNTs. Our studies indicate that the HER catalytic efficiency of transition metal phosphide catalysts can be improved significantly by adjusting active phase and carbon species structures.

Exploring new hybrid catalysts to replace Pt-based catalysts for the hydrogen evolution reaction (HER) is important for various renewable energy applications. However, the design and synthesis of such catalysts are still challenging. Herein, we focus on the development of a series of hybrid materials consisting of cobalt nickel phosphide nanoparticles (NPs) decorated carbon nanotubes (Co2−xNixP/CNTs) as efficient catalysts for enhanced HER catalytic activity. All the X-ray spectra including X-ray diffraction, X-ray photoelectron spectroscopy and X-ray adsorption spectroscopy demonstrate that the crystalline phase structure, valence and coordination environment of hexagonal Ni2P are changed with increasing Co atoms. Electrochemical measurements show that the Co2−xNixP/CNT hybrids exhibit high activity and stability for the HER in acidic solution. The as-synthesized Co1.6Ni0.4P/CNT hybrid exhibits the highest electrocatalytic activity with low onset overpotential (36.1 mV), a small Tafel slope (46.7 mV dec−1), a much larger exchange current density (1.86 × 10−5 A cm−2), lower HER activation energy (57.3 kJ mol−1), and good stability. Such enhanced catalytic activity originates from the introduction of Co and strong synergistic effects between CNTs and Co2−xNixP. Meanwhile, density functional theory calculations also confirm that the higher HER catalytic activity of the Co2−xNixP/CNTs can be attributed to the splendid migratory aptitude of adsorbed single H atoms and the lower energy barrier for H2 formation after the introduction of Co atoms. The as-synthesized Co2−xNixP/CNT hybrid catalysts have great potential practical application in water splitting.

In this paper, an efficient method to fabricate Al-based metal organic framework (Al-MOF) MIL-96 crystals with controllable size and morphology, by mixing other forms of reactants to replace the coordination modulators or capping agents, is presented. The size and morphology of the MIL-96 crystals can be selectively varied by simply altering the ratio of dual reactants via their hydrolysis reaction. All the samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Infrared (FT-IR) spectroscopy, thermogravimetric analysis (TGA) and nitrogen sorption. Then based on the BFDH theory, a mechanism for the impact of hydrolysis of reactants on the crystal size and morphology is presented and discussed. We also evaluated the performance of these MOFs as sorbents for capturing CO2, and they all show enhanced adsorption properties compared with the bulk material, displaying high adsorption capacities on CO2 at atmospheric pressure and ambient temperature.

Designing efficient, stable and inexpensive electrocatalysts to replace Pt-based catalysts for the hydrogen evolution reaction (HER) is highly desired in renewable energy research. In this study, we report the synthesis of nickel phosphide nanoparticles decorated on multiwalled carbon nanotubes (Ni2P/CNT) by in situ thermal decomposition of nickel acetylacetonate as a nickel source and trioctylphosphine as a phosphorus source in oleylamine solution of CNT. As a novel HER electrocatalyst, the Ni2P/CNT nanohybrid exhibits excellent electrocatalytic activity in 0.5 M H2SO4 with a low onset overpotential (88 mV), a small Tafel slope (53 mV dec−1), a high exchange current density (0.0537 mA cm−2) and good stability. It only needs overpotentials of 98 and 124 mV to attain current densities of 2 and 10 mA cm−2, respectively. In addition, the Ni2P/CNT nanohybrid shows nearly 100% Faradaic efficiency in acid solutions. This work successfully demonstrates that the introduction of Ni2P NPs into CNT for enhanced electrocatalytic properties is feasible, and that this may open up a potential way for designing more efficient Ni2P-based catalysts for the HER.

A novel and highly active hybrid catalyst for the hydrogen evolution reaction (HER) is constructed by the in situ growth of CoP on the surface of MoS2 and CNTs. The CoP/MoS2-CNTs hybrid catalyst exhibits Pt-like catalytic activity for the HER with an overpotential close to zero, a Tafel slope of 42 mV dec−1 and good stability, which is the best among all non-noble metal catalysts.

Monodispersed nickel phosphide nanocrystals (NCs) with different phases (Ni12P5, Ni2P and Ni5P4) were synthesized via the thermal decomposition approach using nickel acetylacetonate as the nickel source, trioctylphosphine as the phosphorus source and oleylamine in 1-octadecene as the reductant. The phases of the as-synthesized nickel phosphide NCs could easily be controlled by changing the P:Ni precursor ratio. The structure and morphology of the as-synthesized nickel phosphide NCs were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and N2 adsorption–desorption. A formation mechanism for the as-synthesized nickel phosphide NCs was proposed. We further studied the influence of the phase of the nickel phosphide NCs on the electrocatalytic properties for the hydrogen evolution reaction (HER). All phases showed good catalytic properties, and the Ni5P4 NCs with a solid structure exhibited higher catalytic activity than the Ni12P5 and Ni2P NCs. This superior catalytic activity is attributed to the higher positive charge of Ni and a stronger ensemble effect of P in Ni5P4 NCs. This study demonstrates that the crystalline phase is important for affecting the electrocatalytic properties.

The geometrical and electronic structures and photocatalytic performance of subnanometer Agn clusters (n = 2–6) deposited on AgBr(110) are studied under the framework of density functional theory (DFT) plus Hubbard U contributions. The most stable adsorption is facilitated by AgBr(110) interacting with the most stable structure of Agn and results in a new metal-induced gap band (MIGB) located between the valence (VB) and the conduction bands (CB). Both the MIGB and CB are mainly contributed by the sp hybridization states from the metal clusters, while the VB is composed primarily of the 4p states of the surface Br and the 4d states of Ag from both the adsorbate and the surface. The variety of the electronic structures favors visible and infrared light absorption, which strengthens substantially as the cluster size is enlarged. The dominant localization of the photo-excited electrons on the Agn clusters facilitates the oxidation–reduction reactions occurring on the surface and reduces effectively the photolysis of AgBr under sunlight irradiation. The overpotentials of the CB and VB edges indicate that photocatalytic conversion of CO2 with H2O to methanol is possible on AgBr(110) deposited with the Agn clusters which has been realized experimentally.

Many strategies, such as doping metal, designing low-dimensional nanostructures, and enhancing the utilization of active sites based on a conductive support, have been intensively pursued to improve the intrinsic activity of transition metal chalcogenides for the hydrogen evolution reaction (HER). However, integrating all the above-mentioned merits into one electrocatalyst is still a significant challenge. Herein, we have successfully prepared uniform CoMoS/CoMoO4 (CMS) shell–core nanorods, with a diameter of 60 nm and a length of 800 nm, supported on N-doped reduced graphene oxide (NRGO). The obtained CMS/NRGO can combine many advantages, including transition metal doping, one-dimensional nanorods, and the superior conductivity of NRGO, resulting in very promising HER properties and excellent stability. The optimum sulfurization temperature for unsupported CMS nanorods has been explored using uniform CoMoO4 nanorods as a precursor. Although CMS-3 prepared with a sulfurization temperature of 300 °C has been found to possess the optimum activity for the HER, when adopting NRGO as a support, CMS-3/NRGO exhibits an impressive enhancement in HER performances with a low overpotential of 80 mV, a small Tafel slope of 58 mV dec−1, and a large exchange current density of 428 μA cm−2. In addition, the electrocatalytic activity of CMS-3/NRGO shows a negligible delay after 1000 cycles, indicating its robust electrochemical stability in acid electrolyte solution. Therefore, adopting low-temperature sulfurization of one-dimensional metal oxide precursors supported on NRGO may be a promising strategy for obtaining excellent electrocatalysts for the HER.