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Polyoxometalate-based metal-organic frameworks (POMOFs) with bifunctional Lewis-Brønsted acid were designed by confining polyoxometalates (POMs: phosphotungstic acid (PW), phosphomolybdic acid (PMo) or silicotungstic acid (SiW)) within the Zr-MOFs. The confined POMs not only have their own Brønsted acid, but can also regulate the Lewis acid strength of the POMOFs via charge regulation, ultimately allowing the POMOFs to display superior catalytic performance in the tandem catalysis of furfural (FAL) to γ-valerolactone (GVL). Among the three catalysts (POMOF-PW, POMOF-PMo and POMOF-SiW), a complete conversion of FAL was achieved, while POMOF-PW exhibited the highest GVL yield (58.1 %) at 160 °C within 23 h. The leaching experiment and structural characterization of the catalyst before and after recycling confirmed the stability of the catalyst structure. The humin originates from the polymerization of furan ring-containing compounds driven by Brønsted acid. The adsorption configuration of the substrate molecules on the catalyst offers a new explanation for the tandem reaction process, i.e. that perpendicular adsorption performs only the first step of the tandem reaction, while the coexistence of perpendicular and horizontal adsorption permits the entire reaction process. This work gives unique insights into the tandem reaction of FAL and can guide the design of efficient tandem reaction catalysts. A synthetic strategy has been developed to construct polyoxometalate-based metal-organic framework (POMOF) with bifunctional Lewis-Brønsted acid sites by chemically confining polyoxometalates (POM) in metal-organic framework (MOF) channels. Confined POM not only endows the catalyst with Brønsted acid sites, but also enhances the acid strength of the catalyst through charge regulation, which finally promotes the catalyst to exhibit excellent catalytic performance in the multi-step cascade catalysis from furfural (FAL) to γ-valerolactone (GVL). This work also provides insight into the origin and driving sites of the by-product humin, as well as the role of the adsorption configuration in the catalytic process. A look into the future of the multi-step tandem reaction of FAL to GVL is presented. [Display omitted] [ABSTRACT FROM AUTHOR]

• A complete Co doping range up to its solid solubility limit in FeSe have been successfully grown. • The typical lateral size of Fe 1-x Co x Se single crystals is 1–5 mm. • All the samples show metalic behaviour in contrast to a metal insulator transition of Cu doped FeSe. A series of tetragonal Fe 1-x Co x Se single crystals with a complete Co doping range (0 ≤ x ≤ 0.52) up to its solid solubility limit in FeSe have been grown by an eutectic AlCl 3 /KCl molten salt method. The typical lateral size of as-grown Fe 1-x Co x Se single crystals is 1–5 mm. The chemical composition and homogeneity of the crystals was examined by both inductively coupled plasma atomic emission spectroscopy and energy dispersive spectrometer. X-ray diffraction analysis demonstrates that the crystal lattice parameters a and c are both linearly decreased with increasing Co doping level x. In the whole doping range, all the samples show metallic behaviour in contrast to a metal insulator transition of Cu-doped FeSe according to the resistivity measurements. [ABSTRACT FROM AUTHOR]

• The composition homogeneous CuFeSe 2 single crystals with 1.6 × 1.2 × 1.0 mm3 in size are successfully grown. • The intrinsic ferrimagnetic transition occurs below T C = 146 K without other magnetic impurity interference. • An abrupt increase of resistivity below T C revealing a semiconducting behavior. An eutectic AlCl 3 /KCl molten salt method in a horizontal configuration was employed to grow millimeter-sized and composition homogeneous CuFeSe 2 single crystals due to the continuous growth process in a temperature gradient induced solution convection. The typical as-grown CuFeSe 2 single crystals in cubic forms are nearly 1.6 × 1.2 × 1.0 mm3 in size. The chemical composition and homogeneity of the crystals was examined by both inductively coupled plasma atomic emission spectroscopy and energy dispersive spectrometer with Cu:Fe:Se = 0.96:1.00:1.99 consistent with the stoichiometric composition of CuFeSe 2. The magnetic measurements suggest a ferrimagnetic or weak ferromagnetic transition below T C = 146 K and the resistivity reveals a semiconducting behavior and an abrupt increase below T C. [ABSTRACT FROM AUTHOR]

Holey layered HEO nanocrystals with surface FLP sites have been synthesized via a temperature-variable topological transition. Merits of high-entropy oxides and nanoscale effects are favored yielding a superior catalytic performance toward the transfer hydrogenation (CTH) reaction of biomass-derived carbonyl compounds at mild conditions. Mechanistic investigation indicates that the formation of active regions between FLPs provides a stronger driving force for dissociating alcohols and activating the carbonyl groups of substrates, accounting for the enhanced catalytic activity. [Display omitted] • Holey layered high entropy oxide (HEO) nanocrystals with abundant frustrated Lewis pairs (FLPs) have been synthesized. • Combination of HEO properties and nanoscale effect drives FLPs concentrations of as-obtained catalyst up to 585.4 μmol/g. • Catalysts display superior catalytic activity and cycling performance toward the CTH reaction under mild conditions. • FLPs provide stronger driving forces for dissociating alcohols and activating the carbonyl groups of substrates. • Direct hydrogen transfer dominates the catalytic reaction over holey lamellar HEO catalysts. Creating frustrated Lewis pairs (FLPs) on stable high-entropy oxides (HEOs) is a new challenge, and also an uncultivated field in catalysis. Herein, holey layered HEO spinel nanocrystals with rich FLPs were synthesized via a temperature-driven topological transition. The FLPs on the surface of HEO spinel nanocrystals are created by oxygen vacancies (Lewis acid sites) and proximal surface hydroxyls or surface lattice oxygen (Lewis base sites). Rich FLPs furnish HEO nanocrystals a superior activity towards the catalytic transfer hydrogenation reaction of biomass-derived carbonyl compounds at mild conditions. The active regions in between FLPs provide a strong driving force for dissociating alcohols and activating carbonyl groups of substrates, as evidenced by the attenuated total reflectance-infrared spectroscopy (ATR-IR) analysis, which enhances the catalytic activity. This work develops a new kind of hydrogenation catalysts and provides a perspective for creating solid FLPs. [ABSTRACT FROM AUTHOR]

In the catalytic transfer hydrogenation of biomass-derived ML into γ-GVL, we propose a one-step strategy for catalyst preparation and the CTH reaction. Using the strategy, the production of γ-GVL was performed with 2-PrOH as solvent over in situ reduced nano-Cu/AlOOH catalyst from Cu 2 (OH) 2 CO 3 /AlOOH. Meanwhile, the catalyst is heterogeneous and of high catalytic activity and stability due to the stability of the zero-valent copper in the catalyst and the nanosized catalyst. [Display omitted] • In situ reduction Cu/AlOOH catalystsefficiently participated in the CTH reaction from ML to γ-GVL with 2-PrOH as solvent. • In situ reduced Cu/AlOOH showed high catalytic activity and stability. • The excellent nature is attributed to the stability of the zero-valent copper and the nanosized particles of the catalyst. • The catalysts show general applicability to other carbonyl compounds. Catalytic transfer hydrogenation (CTH) of carbonyl compounds is considered as one of the most promising processes in the synthesis of fuels and chemicals. In this work, we propose a one-step strategy for catalyst preparation and CTH. Using the strategy, the production of γ-valerolactone (γ-GVL) was performed with isopropanol (2-PrOH) as solvent over in situ reduced nano-Cu/AlOOH catalyst from Cu 2 (OH) 2 CO 3 /AlOOH and the optimal reaction conditions for γ-GVL are 180 °C for 5 h using the in situ reduced catalyst with Cu/Al molar ratio 3/1 (90.51% yields of γ-GVL). Furthermore, it has been confirmed by different characterization methods (such as: SEM, TEM, XPS, etc.) that the catalyst is heterogeneous and exhibits high catalytic activity and stability which is attributed to the stability of the zero-valent copper in the catalyst and the nanosized particles of the catalyst. In addition, the catalysts also show general applicability to other carbonyl compounds. [ABSTRACT FROM AUTHOR]

Graphical abstract We prepared the catalysts through the ion-exchange of natural calcium montmorillonite with an aqueous aluminum trichloride solution. Al3+ was a good Lewis acid catalyzing the isomerization of glucose to fructose, and the partially hydrolyzed Al−OH groups acted as Brønsted acid for the dehydration of fructose to HMF, which can be extracted by THF with a high yield. Highlights • A series of Al-mont-n were prepared with ion-exchange method for conversion of carbohydrates to HMF. • The catalytic activity is dependent on the concentrations of Al3+ ion. • A high yield of HMF (80.4%) was produced from glucose. • 60.1% and 81.6% yield of HMF were obtained from the dehydration of starch and inulin, respectively. Abstract Aluminum ion-exchanged Ca-montmorillonite with different concentrations of aluminum ion were prepared and applied in the conversion of carbohydrates to 5-hydroxymethylfurfural (HMF). It was found that two types of acid sites were present in the catalyst, Lewis acid sites for isomerization of glucose and Brønsted acid sites for dehydration of fructose. With Al-mont-10 as catalyst, the yield of HMF converted from glucose was 80.4% in a biphase system (THF: NaCl solution) at 180 °C for 2.5 h. Further, the catalyst also shows excellent catalytic performance in the conversion of starch and inulin, and the yield of HMF reached 60.1% and 81.6% under identical conditions, respectively. [ABSTRACT FROM AUTHOR]

• Zirconium ion-intercalated montmorillonite was synthesized by a facile method. • The amount of Lewis and Bronsted acids could be altered by changing the concentration of zirconium ions. • One-pot cascade conversion of FAL to GVL was achieved under mild conditions. • Over 99% furfural conversion and 50.4% GVL yield were attained. A series of ultrathin metal intercalated montmorillonite (Mont) nanosheet materials were prepared and characterized for the one-pot cascade conversion of furfural (FAL) to obtain γ-valerolactone (γ-GVL). The coordination of the intercalated metal ions and the hydroxyl groups between the montmorillonite layers leads to an increase in the specific surface area and pore volume of the material, which coupled with the acidity of the metal ions themselves improves the catalytic performance of the material. Thus Zr-Mont-0.1 exhibited optimal catalytic performance with 100% conversion of FAL and 50.4% yield of GVL under mild conditions, and more importantly, the catalyst maintained its good catalytic performance after the fourth use. Meanwhile the number of Lewis and Brønsted acid sites in the Zr-Mont catalyst can be varied by adjusting the zirconium ion concentration. The proposed reaction mechanism provides initial insights into the role of metal-functionalized montmorillonite in catalyzing the reaction. In addition, the ten-fold magnification reaction confirmed the potential industrial application of the catalyst. [Display omitted] [ABSTRACT FROM AUTHOR]

Summary The Palmer drought model that was developed half a century ago has often been used for monitoring and decision making. It has gained wide-spread familiarity and acceptance, together with numerous complaints, criticisms and improvements. This study first introduces a recent variation of Palmer’s model, i.e. the standardized Palmer drought index (SPDI) as a hybrid of a Palmer drought index (PI) and a standardized drought index (SI). Then, a more complicated methodology is employed to propose an SPDI-based joint drought index (SPDI-JDI), which is also physically based on the Palmer drought model and is a multivariate SI in nature. Using meteorological observations from twelve WMO gauges from all around the globe, empirical and parametric copula-based approaches are adopted and compared for the construction of SPDI-JDI. The findings in this study indicate that the SPDI-JDI derived from parametric copulas can provide an overall measure of the joint probability-based drought status by combining the probabilistic properties and dependence structure of multi-temporal scale marginals of SPDI. Meanwhile, the SPDI-JDI shows high coherence and correlation with individual PIs and performs well in drought detection when compared to the integration of Palmer drought severity index, Palmer modified drought index, Palmer hydrologic drought index and Palmer Z index as well as to the U.S. Drought Monitor observations. Taken together, new variations of the SPDI-JDI and/or SPDI are expected to bring new vigor and vitality into Palmer’s drought model, making it more up-to-date for drought monitoring and prediction. [ABSTRACT FROM AUTHOR]

A stable and easily separable Fe 3 O 4 -12 nanoparticles exhibited the desired catalytic performance in the catalytic transfer hydrogenation reaction of furfural to furfuryl alcohol with 2-propanol as the hydrogen source. Moreover, a feasible flowchart from xylose to FOL was designed. Utilizing the process can realize the regeneration of biomass resources, the reuse and recycling of catalysts and solvents, and minimize the amount of solvents and pollutant emissions. • Magnetic Fe 3 O 4 -12 nanoparticles exhibited excellent catalytic performance for the CTH reaction of FAL to FOL. • A feasible flowchart from xylose to FOL was designed, which can realize the valorization of biomass resources. • Fe 3 O 4 -12 nanoparticles have good recyclability and universality for different carbonyl compounds. Magnetic Fe 3 O 4 -12 nanoparticles, an easily separable heterogeneous catalyst, exhibits high catalytic performance in the catalytic transfer hydrogenation (CTH) reaction of biomass-derived furfural (FAL) to furfuryl alcohol (FOL) with 2-propanol (2-PrOH) as the hydrogen source (90.1 % FOL yield at 160 °C for 5 h). Comparing Fe 3 O 4 nanoparticles with different particle sizes found that the smaller the nanoparticles, the larger the BET surface area, pore volume and pore diameter, resulting in more acid-base active sites through BET, SEM, TEM, NH 3 -/CO 2 -TPD and other characterizations. Moreover, a scaled-up CTH experiment of FAL and a stepwise reaction from xylose to FOL verified that the catalytic system has great industrial application prospects. A feasible flowchart of the chemical process from xylose to FOL was designed, which can realize the regeneration of biomass resources (xylose derived from corncob), the reuse and recycling of catalysts and solvents, and minimize the amount of solvents and pollutant emissions. [ABSTRACT FROM AUTHOR]

The transformation of lignocellulosic biomass to platform compounds (γ-valerolactone, GVL) was a significant component in biomass development. Herein, sulfonated Zr-based metal-organic frameworks (MOF-808), a bifunctional heterogeneous catalyst with Lewis and Bronsted acid sites, were prepared to catalyze the one-pot cascade reaction of furfural (FUR) to GVL. The successful modification of the sulfonic group on MOF-808 was substantiated by multiple characterization methods. By adjusting the sulfuric acid concentration to balance the Lewis acid and Bronsted acid sites of the catalyst, S-808–2.37 was confirmed as the preferred catalyst and a 60.4 % GVL yield was achieved with 99.1 % carbon balance under the optimal conditions. Moreover, the 72.8 % GVL yield reached in the 40x magnification experiment also boded well for the catalyst's application potential. The work in this paper opened up new perspectives for the application of MOF-808 porous materials in the field of selective catalytic conversion of biomass involving multi-step reactions. [Display omitted] • Strong interaction between Zr and OH of H 3 BDC led to the formation of strong Lewis acidic/basic sites in the frameworks. • The cooperative role of strong Lewis acidic/basic sites in the S-808–2.37 contributed to the excellent catalytic performance. • This work provided a promising strategy to modulate the acid-base properties of MOF-808 without affecting its structure. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Chemical substitution during growth is a well-established method to manipulate electronic states of quantum materials, and leads to rich spectra of phase diagrams in cuprate and iron-based superconductors. Here we report a novel and generic strategy to achieve nonvolatile electron doping in series of (i.e. 11 and 122 structures) Fe-based superconductors by ionic liquid gating induced protonation at room temperature. Accumulation of protons in bulk compounds induces superconductivity in the parent compounds, and enhances the T c largely in some superconducting ones. Furthermore, the existence of proton in the lattice enables the first proton nuclear magnetic resonance (NMR) study to probe directly superconductivity. Using FeS as a model system, our NMR study reveals an emergent high- T c phase with no coherence peak which is hard to measure by NMR with other isotopes. This novel electric-field-induced proton evolution opens up an avenue for manipulation of competing electronic states (e.g. Mott insulators), and may provide an innovative way for a broad perspective of NMR measurements with greatly enhanced detecting resolution. [ABSTRACT FROM AUTHOR]

Water scarcity causes conflicts among natural resources, society and economy and reinforces the need for optimal allocation of irrigation water resources in a sustainable way. Uncertainties caused by natural conditions and human activities make optimal allocation more complex. An intuitionistic fuzzy multi-objective non-linear programming (IFMONLP) model for irrigation water allocation under the combination of dry and wet conditions is developed to help decision makers mitigate water scarcity. The model is capable of quantitatively solving multiple problems including crop yield increase, blue water saving, and water supply cost reduction to obtain a balanced water allocation scheme using a multi-objective non-linear programming technique. Moreover, it can deal with uncertainty as well as hesitation based on the introduction of intuitionistic fuzzy numbers. Consideration of the combination of dry and wet conditions for water availability and precipitation makes it possible to gain insights into the various irrigation water allocations, and joint probabilities based on copula functions provide decision makers an average standard for irrigation. A case study on optimally allocating both surface water and groundwater to different growth periods of rice in different subareas in Heping irrigation area, Qing’an County, northeast China shows the potential and applicability of the developed model. Results show that the crop yield increase target especially in tillering and elongation stages is a prevailing concern when more water is available, and trading schemes can mitigate water supply cost and save water with an increased grain output. Results also reveal that the water allocation schemes are sensitive to the variation of water availability and precipitation with uncertain characteristics. The IFMONLP model is applicable for most irrigation areas with limited water supplies to determine irrigation water strategies under a fuzzy environment. [ABSTRACT FROM AUTHOR]

[Display omitted] • An in-situ electrochemical oxidation of tunnel-like V 2 O 3 to layered V 5 O 12 ·6H 2 O upon initial cycling takes place. • V 5 O 12 ·6H 2 O provides substantial active sites for zinc ion storage and accelerates Zn2+ diffusion kinetics. • Co-embedding of Zn2+ and H 2 O molecules during cycling enlarges the layer spacing. • The carbon layer covering on the electrode improves electrode stability and enhances electron conductivity. • The oxidized V 2 O 3 -C electrode presents excellent rate performance and cycling performance at low current density. In-situ electrochemical activation can bring about unexpected improvement for electrode materials, while the nature behind the structural evolution during this activation remains unclear, which to a great extent limits the applications in searching for efficient cathodes for rechargeable zinc-ion battery (ZIB) with outstanding rate performance. Herein, we report on in-situ electrochemical oxidation of V 2 O 3 -C cathode for boosted zinc-ion storage performance. A solvothermal method is implemented to directly synthesize V 2 O 3 nanoparticles coated with a carbon layer. Detailed characterizations reveal that due to co-embedding of H 2 O and Zn2+, tunnel-like V 2 O 3 undergoes an in-situ electrochemical oxidation to generate layered V 5 O 12 ·6H 2 O upon initial cycling. The intercalation of H 2 O molecules results in an expansion of layer spacing, accelerating the Zn2+ diffusion kinetics. As a consequence, a symmetric cell equipped with activated V 2 O 3 -C electrode delivers a high-rate capability (349 mA h g−1 at 1000 mA g−1) and superior specific capacity (260 mA h g−1 at 100 mA g−1 after 100 cycles). The strategy of in-situ electrochemical oxidation delivers the guidance to tunnel-like materials as cathode for rechargeable ZIBs. [ABSTRACT FROM AUTHOR]

Summary: This study first focuses on comprehensive evaluating three widely used satellite precipitation products (TMPA 3B42V6, TMPA 3B42RT, and CMORPH) with a dense rain gauge network in the Mishui basin (9972km2) in South China and then optimally merge their simulated hydrologic flows with the semi-distributed Xinanjiang model using the Bayesian model averaging method. The initial satellite precipitation data comparisons show that the reanalyzed 3B42V6, with a bias of −4.54%, matched best with the rain gauge observations, while the two near real-time satellite datasets (3B42RT and CMORPH) largely underestimated precipitation by 42.72% and 40.81% respectively. With the model parameters first benchmarked by the rain gauge data, the behavior of the streamflow simulation from the 3B42V6 was also the most optimal amongst the three products, while the two near real-time satellite datasets produced deteriorated biases and Nash–Sutcliffe coefficients (NSCEs). Still, when the model parameters were recalibrated by each individual satellite data, the performance of the streamflow simulations from the two near real-time satellite products were significantly improved, thus demonstrating the need for specific calibrations of the hydrological models for the near real-time satellite inputs. Moreover, when optimally merged with respect to the streamflows forced by the two near real-time satellite precipitation products and all the three satellite precipitation products using the Bayesian model averaging method, the resulted streamflow series further improved and became more robust. In summary, the three current state-of-the-art satellite precipitation products have demonstrated potential in hydrological research and applications. The benchmarking, recalibration, and optimal merging schemes for streamflow simulation at a basin scale described in the present work will hopefully be a reference for future utilizations of satellite precipitation products in global and regional hydrological applications. [Copyright &y& Elsevier]