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Currently, biomass transformation to produce high value-added chemicals and liquid biofuels is attracting more and more interest by the virtue of its importance in the sustainable development of human society. Herein, we reported the conversion of furfural (FFA) into cyclopentanone (CPO) in water over high performing and stable Cu/ZrO 2 catalysts prepared by our developed one-pot reduction-oxidation method. It was demonstrated that surface structures and catalytic performances of catalysts could be delicately adjusted by varying the calcination temperatures for catalyst precursors. Especially, an appropriate calcination temperature of 500 °C could significantly enhance the interactions between surface Cu species and the ZrO 2 support, thus greatly facilitating the formation of Cu + -O-Zr-like structure at the metal-support interface, and the resulting Cu/ZrO 2 catalyst showed a superior catalytic performance with a high CPO yield of 91.3% under mild reaction conditions (i.e. a low hydrogen pressure of 1.5 MPa and 150 °C) to other metal oxides supported copper catalysts prepared by the conventional impregnation. It was revealed that in addition to surface acidic sites, surface Cu + /(Cu°+Cu + ) ratio also played a key role in promoting the formation of CPO in the present Cu/ZrO 2 catalytic system. [ABSTRACT FROM AUTHOR]

Design and development of novel and efficient catalysts are crucial but challenging for the catalytic conversion of biomass and derivatives to fuels and chemicals. In this paper, a novel separate nucleation and aging steps assistant reduction-oxidation strategy was developed to synthesis CuO/ZrO 2 complex precursor with homogeneously distributed Cu and Zr components, which can be used as an ideal precursor for the synthesis of highly dispersed Cu/ZrO 2 catalyst. Characterization results revealed that homogeneous dispersion of CuO, high surface area of ZrO 2 support with controlled porous structure, and strong interaction between CuO and ZrO 2 in CuO/ZrO 2 precursor could lead to the enhanced Cu dispersion and the formation of Cu + active centers. The synthesized Cu/ZrO 2 catalysts exhibited excellent catalytic performance (85.4% conversion of GVL and 98.0% selectivity of pentyl valerate) in the catalytic transformation of GVL to valerate esters, more efficient than that of Cu/ZrO 2 -CP and Cu/ZrO 2 -CH catalysts prepared via co-precipitation and chemisorption hydrolysis methods, respectively. The superior catalytic performance was mainly attributed to both the cooperation of Cu 0 and Cu + species and the highly dispersed surface Cu 0 , thereby improving the adsorption and polarization of C O bond in GVL and the following dissociation of H 2 to produce active hydrogen for the hydrogenation step during the catalytic transformation of GVL. Moreover, such copper-based catalysts exhibited potential applications in the exploitation and utilization of biomass resources with significantly enhanced efficiency. [ABSTRACT FROM AUTHOR]

The selective oxidation of alkanes and alkylaromatics to corresponding alcohols, ketones or carboxylic acids is of great importance for the production of high added-value raw materials in the fine chemical industry. The design and synthesis of cost-effective and recyclable heterogeneous oxidation catalysts has become one of the most active research areas. In this work, a series of novel Al 2 O 3 @Co–Cu–Al mixed metal oxide (Al 2 O 3 @CoCuAl-MMO) catalysts with hierarchical flower-like microstructure were successfully prepared via a Co–Cu–Al layered double hydroxide precursor route, and their catalytic performance was investigated in the liquid-phase selective oxidation of ethylbenzene using tert-butyl hydroperoxide as oxidant without the addition of any organic solvents. The characterization results revealed that the incorporation of copper into the MMO could induce the formation of the interactions between the Co–Cu species, and thus catalytic performance of as-formed Al 2 O 3 @CoCuAl-MMO catalysts was significantly promoted. In the selective oxidation of ethylbenzene, a high conversion of 92.8% with an acetophenone selectivity of 89.4% was achieved over the Al 2 O 3 @CoCuAl-MMO catalyst with a Cu/(Cu + Co) molar ratio of 0.25. The high catalytic efficiency was attributed mainly to the synergistic effect between highly dispersed active Co and Cu species. More importantly, the obtained catalysts having good recyclability and stability displayed good catalytic performance in the oxidation of other alkanes and alkylaromatics including 1,2,3,4-tetrahydronaphthalene, toluene, cumene, and methylcyclohexane. [ABSTRACT FROM AUTHOR]

A novel highly sensitive non-enzymatic glucose sensor was constructed based on gold nanoparticles decorated ternary Ni-Al layered double hydroxide/single-walled carbon nanotubes/graphene nanocomposite (Au/LDH-CNTs-G). The materials were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance spectra and Raman spectra, and the sensing performance was investigated by electrochemical impedance spectroscopy, cyclic voltammetry and amperometric response. The results revealed that Au/LDH-CNTs-G nanocomposite modified glassy carbon electrode exhibited remarkable electrocatalytic performance toward glucose oxidation, with a wide linear range from 10 μM to 6.1 mM, a high sensitivity of ∼1989 μA·mM −1 ·cm −2 and a low detection limit of 1.0 μM based on a signal to noise ratio of 3, which was mainly attributed to the combined effects of enhanced electrical conductivity originating from three-dimensional intertwined CNTs-graphene network, good accessibility to active reaction sites from NiAl-LDH and more electron transfer passages provided by Au nanoparticles highly dispersed on the surface. What's more, as-constructed non-enzymatic sensor showed good reproducibility, repeatability, stability and anti-interference property, and was also used to practically analyze glucose concentration in human serum samples. [ABSTRACT FROM AUTHOR]

Highlights: [•] Tailored flower-like CuO micro/nanostructures were grown directly on Cu foils. [•] The CuO electrodes showed remarkably high sensitivities towards glucose detection. [•] The CuO electrode exhibited enhanced anti-interference and anti-poisoning property. [•] The enhanced performances are related to specific hierarchical micro/nanostructure. [Copyright &y& Elsevier]

Currently, the catalytic hydrodeoxygenation (HDO) of oxygen-containing compounds derived from biomass to highly valuable chemicals or hydrocarbon bio-fuels is attracting more and more attention. Concerning the design and synthesis of high-performance supported metal catalysts for HDO, the efficient deposition/immobilization of active metal species on supports, as well as the construction of the favorable properties of supports, is quite necessary. In this work, we fabricated series of aluminum-zirconium oxide solid solution supported Ni-based catalysts by a simple surfactant-assisted homogeneous coprecipitation and applied them in the HDO of anisole. Various structural characterizations showed that surface-interface properties of Ni-based catalysts (i.e., surface acidity, defective structures, and metal-support interactions) could be finely tuned by adjusting the amount of Al introduced into Al-Zr oxide solid solutions, thus profoundly governing their catalytic HDO activities. It was demonstrated that the introduction of an appropriate amount of Al could not only enhance surface acidity and promote the formation of defective Zr-O v -Al structures (O v : oxygen vacancy) but also facilitate the generation of interfacial Niδ+ species bound to the support. Over the Ni-based catalyst bearing an Al 2 O 3 :ZrO 2 mass ratio of 5:2, a high cyclohexane yield of ∼77.4% was attained at 230 °C and 1.0 MPa initial hydrogen pressure. The high catalytic HDO efficiency was revealed to be correlated with the catalytic synergy between Ni0 and adjacent interfacial Niδ+ species, together with the promotion of neighboring defective oxygen vacancies and acidic sites, which contributed to the enhanced activation of the methoxy group in anisole and reaction intermediate and thus greatly improved HDO activity. The present findings offer a new and promising guidance for constructing high-performance metal-based catalysts via a rational surface-interface engineering. [Display omitted] • Highly dispersed Ni nanoparticles were stabilized by the Zr-Al oxide solid solution. • Such-fabricated Ni-based nanocatalyst was highly active for anisole hydrodeoxygenation. • Unique synergies of surface-interface multiple active sites were constructed. • Ni0 sites together with interfacial Niδ+ sites and surface defective and acidic sites contributed to high efficiency. [ABSTRACT FROM AUTHOR]

Abstract: High-surface-area ZnAl2O4 with micro/mesoporous frameworks was synthesized via a facile one-pot solvothermal approach without using any surfactants or post-treatment. The results revealed that the textural properties of micro/mesoporous ZnAl2O4 were tuned by changing alcohol/water mixture solvents used in solvothermal synthesis and Ag nanoparticles were dispersed uniformly on the surface of ZnAl2O4 supports. Especially, the supported Ag catalyst on the microporous ZnAl2O4 synthesized in methanol/water solvent exhibited good catalytic performance for liquid phase selective hydrogenation of o-chloronitrobenzene to o-chloroaniline, owing to the high dispersion of Ag nanoparticles and the strong metal-support interaction. [Copyright &y& Elsevier]

Abstract: In this paper, we report on the three-dimensional nanostructured Cu2O/CuO films with controlled flower-like shapes using a direct crystallization approach in the presence of sodium borohydride without using any performed template, surfactant or oxidant. The microstructures and shapes of Cu2O/CuO architectures were investigated by field emission scanning electron microscopy, X-ray diffraction and transmission electron microscopy. Three types of chrysanthemum-like, candock-like and dandelion-like CuO microstructures consisting of densely packed building blocks of nanobelts or nanoribbons were achieved by governing the concentrations of NaBH4. Possible growth mechanisms for the controlled organization of primary building units into three-dimensional flower-like architectures were proposed. After simple surface modification with sodium laurate, the resulting films displayed hydrophobic and even superhydrophobic properties owing to their special surface nano-/microstructures. [Copyright &y& Elsevier]

• Indium-doped ZrO 2 supported copper catalysts were in situ constructed. • As-constructed Cu-based catalysts was highly active for the CO 2 hydrogenation. • In situ introduction of indium could tune effectively surface-interface structures. • Surface basicity together with interfacial defects/Cu+ sites contributed to high efficiency. Currently, highly efficient catalytic CO 2 hydrogenation to produce methanol is attracting intensive attention. However, constructing high-performance catalysts for methanol synthesis that can be operated under mild reaction conditions is a challenging task. In this work, a series of indium-doped ZrO 2 supported copper-based catalysts for CO 2 hydrogenation were constructed via one-pot hydrogen bubble-assisted approach. It was manifested that the in situ introduction of indium facilitated the generation of interfacial defects in the form of Zr-Vo-In3+ structure (V o : oxygen vacancy) and interfacial Cu+ sites, as well as surface basic sites originating from In-O pairs, and the catalytic performance of as-constructed In-doped Cu/ZrO 2 catalysts could be efficiently promoted by tuning the indium content. Specifically, the Cu-based catalyst bearing the indium content of 4.0 wt% afforded the quite high space-time yield of methanol (0.398 g MeOH h−1·g cat −1) at 270 °C, while the one with the indium content of 8.0 wt% yielded an increased methanol selectivity by 1.8 times at 250 °C, compared with undoped one. Combining the structural characterizations with catalytic results, it was found that surface medium-strength and strong basic sites together with the contribution from interfacial defective oxygen vacancies and Cu+ sites played key promotional roles on the synthesis of methanol. This finding enables us to design new high-performance Cu-based catalysts for CO 2 hydrogenation by finely turning their surface-interface structures. [ABSTRACT FROM AUTHOR]

Design of novel catalysts for efficient electro-reduction of CO 2 into value-added chemicals is a promising approach to curb the excessive emission of anthropogenic CO 2 and alleviate the energy crisis, and is still a challenging task because of the high overpotential required, competitive water reduction reaction, and complicated solid-liquid-gas three-phase interfacial reaction pathways. Herein, we successfully fabricated a nickel-nitrogen-modified porous carbon/carbon nanotube hybrid electrocatalyst (Ni-NPC/CNTs) with necklace-like geometry through a three-step assembly process including the integration of Zn-based metal-organic framework (ZIF-8) and carbon nanotube, double-solvent solution impregnation of Ni component, and pyrolysis treatment. Owing to the abundant and dispersive surface Ni-N x and pyridine-N active sites, synesthetic effect between active sites, favored necklace-like geometry with micro-/mesopores, large surface areas, and interconnected electron highway, the as-assembled Ni-NPC/CNTs electrocatalyst exhibits exciting catalytic performance for the selective reduction of CO 2 to carbon monoxide (CO) in 0.5 M KHCO 3 , gives a maximum CO faradaic efficiency of 94% at a moderate overpotential of 660 mV with large current density of 11.2 mA cm−2, and maintains an average CO faradaic efficiency of 92% and high durability over a wide potential range from −0.67 to −1.0 V. Furthermore, this work offers a new direction for the rational design and synthesis of hierarchical hybrid carbon-based electrocatalysts for efficient electro-reduction of CO 2 in the wide potential region. Image 1 [ABSTRACT FROM AUTHOR]

Tetravalent metal oxides, such as ceria and zirconia, are widely used as support materials in a broad range of heterogeneous catalytic processes. Herein, high-surface-area CeO 2 -ZrO 2 composite supports with micro/mesoprous structures were first fabricated successfully by a low temperature solution-phase method without the use of any additional templates and surfactants and resulting supported platinum nanoparticles were employed in liquid-phase selective hydrogenation of cinnamaldehyde to cinnamyl alcohol, a key reaction for the production of important chemicals. It was found that the component of CeO 2 -ZrO 2 composites strongly influenced surface structures of catalysts, and consequently determined the nature of platinum species and the catalytic properties of catalysts. When platinum was dispersed on the CeO 2 -ZrO 2 composite with the Ce/Zr molar ratio of 1:1, a high cinnamyl alcohol yield of 89%, together with an extremely high turnover frequency value of 10423 h –1 , could be achieved without the use of additional alkali. Such high catalytic performance, which was superior to those of most known supported Pt-based catalysts previously reported, was mainly attributable to the synergism between electron-rich metallic Pt species and surface defects (i.e., Ce 3+ species and oxygen vacancies), thereby greatly promoting the chemisorption and activation of carbonyl group in cinnamaldehyde. Moreover, the porous network of CeO 2 -ZrO 2 composites is beneficial to the stabilization of Pt nanoparticles, thereby preventing the leaching and the growth of Pt particles in the course of reaction. This work offers a better understanding of the role of high-surface-area porous CeO 2 -ZrO 2 composite supports for highly efficient selective hydrogenation of α,β-unsaturated aldehydes in supported precious-metal-based catalysts. [ABSTRACT FROM AUTHOR]

Abstract: The gas-phase hydrogenation of dimethyl 1,4-cyclohexane dicarboxylate to 1,4-cyclohexane dimethanol (CHDM) was conducted on well-dispersed supported Cu/ZnO/ZrO2 catalysts. The results indicated that the structure and catalytic performance of resulting copper-based catalysts were profoundly affected by the addition of zirconium. Moreover, the as-synthesized catalyst with 35.0wt.% ZrO2 component was found to exhibit superior catalytic performance with a high CHDM yield of 96.8% to other catalysts, which should be mainly attributed to the significant dispersion effect of ZrO2 on the copper-containing species resulting in a higher metallic copper surface area as well as a larger number of Cu+ species. [Copyright &y& Elsevier]

Simultaneously improve the activity and durability of complex metal oxides based OER electrocatalyst is crucial important for the conversion and storage of renewable energy, and is still confronted with significant challenges because of their easy dissolution and surface reconstruction in alkaline or acid electrolyte, as well as poor electrical conductivity. Herein, CeO x -NiCo 2 O 4 -U/NF electrocatalyst with umbrella-shaped hierarchical structure was synthesized through a three-step processes including the surfactant induced in-situ fabrication of umbrella-shaped nickel-cobalt complex hydroxide precursor on nickel foam, calcination treatment, and potentiostatic electro-deposition of CeO x. Owing to the co-existence of multiple redox couples, synergistic effect between active sites, enriched quantity of surface oxygen defects, multiple electron transport channels, sharp-tip effects originated from the umbrella-shaped hierarchical structure, the as-prepared CeO x -NiCo 2 O 4 -U/NF electrocatalyst exhibited advanced OER activity with a small overpotential of 219 mV at 10 mA cm−2 and Tafel slope of 67 mV dec−1 in 1.0 M KOH solution, and 328 mV in 0.05 M H 2 SO 4 solution with a Tafel slope of 96 mV dec−1, much lower than those of reported nickel- or cobalt-based OER catalyst. Moreover, due to the in-situ fabrication strategy and excellent acid-alkali resistance of NiCo 2 O 4 and CeO x components, the as-prepared CeO x -NiCo 2 O 4 -U/NF electrocatalyst exhibited long-term structure and chemical stability over a broad pH region. Furthermore, the synthetic strategy presented here offers a new method for the rational design and synthesis of complex metal oxides based electrocatalyst for energy conversion and storage applications with excellent catalytic performance and long-term stability. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Efficient and cost-effective electrocatalysts for the oxygen evolution reaction (OER) are of paramount importance for renewable energy conversion and storage. Here, we developed a facile approach for integrating two-dimensional (2D) zeolitic imidazolate framework-67 (ZIF-67) nanoarrays and CoNiAl ternary layered double hydroxide (CoNiAl-LDH) nanoplatelets onto three-dimensional (3D) nickel foam (NF) to form a 3D hierarchical ZIF-67/CoNiAl-LDH/NF electrocatalyst. Due to the unique 3D hierarchical architecture with increased electrochemical active surface area, multi-porous framework, and intimate interfacial coupling effect, the as-prepared ZIF-67/CoNiAl-LDH/NF electrocatalyst exhibits excellent electrocatalytic activity towards OER with a small overpotential of 303 mV at 10 mA cm−2 and Tafel slope around 88 mV dec−1, much lower than those of the reported nickel- or cobalt-based OER catalysts. Moreover, the ZIF-67/CoNiAl-LDH/NF electrocatalyst also shows excellent electrochemical durability, and the hierarchical structure is well maintained with no detectable activity decay after continuous testing at 10 mA cm−2 for 8 h. The present work provides a general strategy for the rational design and synthesis of multi-functional 3D hierarchical catalyst, which is expected to exhibit superior performance in a wide range of catalysis, especially in water electrolysis. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

• Mixed metal oxides (MMOs) were obtained from intercalated ZnAl-LDH precursors. • Interlayer phosphotungstate anion favored enhanced defects and acidity of MMOs. • As-fabricated supported Ru catalyst was highly active for hydrodeoxygenation of guaiacol. • Ru0 sites together with oxygen vacancies and acidic sites contributed to high efficiency. In this work, a strategy for rational design of high-performance heterogenous supported Ru nanocatalysts over mixed metal oxides for aqueous phase partial hydrodeoxygenation (HDO) of guaiacol in the batch reactor was developed taking advantage of supramolecular structure of Zn-Al layered double hydroxides (LDHs) with different interlayer anions. It was interestingly found that in the case of phosphotungstate intercalated ZnAl-LDH as the support precursor, strong interactions between Ru species and intercalated LDH-derived mixed metal oxide supports could be formed, in addition to the formation of surface reductive ZnWO x component and P-O species. Notably, as-fabricated supported Ru nanocatalyst showed much higher activity in the aqueous phase HDO of guaiacol to produce cyclohexanol at an extraordinarily low Ru/guaiacol molar ratio of 0.0009, along with a higher cyclohexanol yield of ∼86% under reaction conditions (250 °C, 2.0 MPa initial H 2 pressure), compared to other two supported Ru ones over mixed metal oxides derived from tungstate- and nitrate-intercalated ZnAl-LDH precursors (cyclohexanol yield of 29.7 and 10.1%, respectively). Studies on structure-property correlations revealed that surface defective and acidic sites facilitated the activation of guaiacol and phenol intermediate, thereby enabling the catalyst with a strong ability to break C ring −OCH 3 bond and promote the ring hydrogenation. This finding provides a promising way to tune surface structures of metal-based catalysts for the upgrading of biomass. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Surface Ru-decorated Co nanocatalysts were in situ fabricated via an LDH precursor route. • The reduction temperature could tune effectively surface density of oxygen vacancies. • As-fabricated Co-based catalysts were highly active for hydrodeoxygenation of guaiacol. • Surface active Ru0/Co0 sites together with oxygen vacancies contributed to high efficiency. In the present work, carbon-supported Ru-decorated Co-based nanocatalysts were fabricated via a layered double hydroxide/carbon composite precursor approach and applied to the efficient hydrodeoxygenation (HDO) of guaiacol to produce cyclohexanol. It was demonstrated that uniform and highly dispersed Co nanoparticles could be formed on the carbon matrix, and the decoration of a small amount of Ru on the surface of Co nanoparticles could introduce stronger hydrogenolysis active sites. Furthermore, the reduction temperature for catalyst precursors could tune the size of Co-containing nanoparticles and regulate the density of surface oxygen vacancies originating from CoO x species. Under the mild reaction conditions (200 ℃ and 1.0 MPa hydrogen pressure), as-fabricated Ru-Co/C catalyst obtained at the reduction temperature of 600 °C showed excellent catalytic activity in the HDO of guaiacol, with a high cyclohexanol yield of ∼94 %, which was attributable to surface exposure of highly dispersive Ru° sites and the formation of abundant defective oxygen vacancies. The present results provide a new approach for designing high-performance Co-based HDO nanocatalysts by both the surface decoration of small amounts of precious metals and the introduction of surface defective structures. [ABSTRACT FROM AUTHOR]

In the work, hybrid nanocomposite of Ni–Al layered double hydroxide (LDH) and carbon nanotubes (LDH/CNTs) was assembled via one-pot hydrothermally assisted coprecipitation approach and applied as the thermal stabilizer in polyvinyl chloride (PVC) resin. Various structural characterizations revealed that smaller LDH nanoplatelets could be uniformly dispersed on the surface of CNTs or closely combined with the CNTs matrix, thus forming unique hybrid nanostructure and strong LDH-CNTs interactions. The thermogravimetry (TGA), Congo red tests, and TG-fourier transform infrared (TG-FTIR) experiments for the PVC-based composites demonstrated that compared with pristine NiAl-LDH and CNTs, as-assembled LDH/CNTs nanocomposite exhibited greatly enhanced thermal stabilization effect on PVC resin. Especially, PVC/LDH/CNTs composite with 5.0 phr of LDH/CNTs additive delivered a superior thermal stabilization effect on PVC to other PVC-based composites, along with the greatly increased maximum degradation temperature and the improved removal efficiency of hydrogen chloride by about 40 °C and 64.8%, respectively. It was concluded that through the assembly of NiAl-LDH with CNTs, the enlarged LDH interlayer spacing, enhanced dispersion of NiAl-LDH component in PVC resin, and strengthened interfacial interaction between NiAl-LDH and PVC could account for the improved thermal stabilization effect of LDH/CNTs additive on PVC during the pyrolysis of PVC. • Hybrid nanocomposite of NiAl-LDH and CNTs was successfully assembled. • Strong interactions between highly dispersive LDH nanosheets and CNTs could form. • As-assembled LDH/CNTs presented excellent thermal stabilization effect on PVC resin. • LDH structure/composition and LDH-PVC interaction affected the stabilization efficiency. [ABSTRACT FROM AUTHOR]