Porous framework materials for energy&environment relevant applications:A systematic review

Carbon peaking and carbon neutralization trigger a technical revolution in energy&environment related fields.Development of new technologies for green energy production and storage,industrial energy saving and efficiency reinforcement,carbon capture,and pollutant gas treatment is in highly imperious demand.The emerging porous framework materials such as metal–organic frameworks(MOFs),covalent organic frameworks(COFs)and hydrogen-bonded organic frameworks(HOFs),owing to the permanent porosity,tremendous specific surface area,designable structure and customizable functionality,have shown great potential in major energy-consuming industrial processes,including sustainable energy gas catalytic conversion,energy-efficient industrial gas separation and storage.Herein,this manuscript presents a systematic review of porous framework materials for global and comprehensive energy&environment related applications,from a macroscopic and application perspective.

Preparation of sodium molybdate from molybdenum concentrate by microwave roasting and alkali leaching

The preparation process of sodium molybdate has the disadvantages of high energy consumption,low thermal efficiency,and high raw material requirement of molybdenum trioxide,in order to realize the green and efficient development of molybdenum concentrate resources,this paper proposes a new process for efficient recovery of molybdenum from molybdenum concentrate and preparation of sodium molybdate by microwave-enhanced roasting and alkali leaching.Thermodynamic analysis indicated the feasibility of oxidation roasting of molybdenum concentrate.The effects of roasting temperature,holding time,and power-to-mass ratio on the oxidation product and leaching product sodium molybdate (Na_(2)MoO_(4)·2H_(2)O) were investigated.Under the optimal process conditions:roasting temperature of 700℃,holding time of 110 min,and power-to-mass ratio of 110 W/g,the molybdenum state of existence was converted from MoS_(2) to Mo O3.The process of preparing sodium molybdate by alkali leaching of molybdenum calcine was investigated,the optimal leaching conditions include a solution concentration of 2.5 mol/L,a liquid-to-solid ratio of 2 mL/g,a leaching temperature of 60℃,and leaching solution termination at pH 8.The optimum conditions result in a leaching rate of sodium molybdate of 96.24%.Meanwhile,the content of sodium molybdate reaches 94.08wt%after leaching and removing impurities.Iron and aluminum impurities can be effectively separated by adjusting the pH of the leaching solution with sodium carbonate solution.This research avoids the shortcomings of the traditional process and utilizes the advantages of microwave metallurgy to prepare high-quality sodium molybdate,which provides a new idea for the highvalue utilization of molybdenum concentrate.

Highly selective electrosynthesis of 3,4-dihydroisoquinoline accompanied with hydrogen production over three-dimensional hollow CoNi-based microarray electrocatalysts

Electrocatalytic oxidation reaction of biomass-based derivatives is an excellent candidate to replace water oxidation for obtaining both value-added products and hydrogen(H_(2)),but the exploration of competent electrocatalysts is still highly challenging.Herein,two new types of three-dimensional self-supported hollow microarrays containing CoNi layered double hydroxide(CoNi-LDH)and N-doped carbon nanosheets decorated with CoNi alloyed nanoparticles(CoNi-NC)on carbon cloth(CC)are prepared,which are further used as efficient electrocatalysts for tetrahydroisoquinoline(THIQ)electrooxidation and hydrogen evolution reaction(HER),respectively.We demonstrate that the Co-modulated electronic environment for Ni(II)/Ni(Ⅲ)redox-looping in CoNi-LDH is the main factor to boost the selectivity of 3,4-dihydroisoquinoline(DHIQ)for the indirect electrooxidation process of THIQ.Density functional theory(DFT)calculations reveal that the Ni(Ⅲ)/Co(Ⅲ)dual sites of CoNi-LDH exhibit enhanced adsorption for THIQ but poorer adsorption for DHIQ compared to pure Co(Ⅲ)or Ni(Ⅲ).Therefore,the Ni(Ⅲ)/Co(Ⅲ)dual sites can effectively inhibit the peroxidation of DHIQ to isoquinoline(IQ)over CoNi-LDH,thus improving the selectivity of DHIQ to nearly 100%,much higher than that of its pure Ni counterpart.Moreover,CC@CoNi-NC can deliver high HER activity with low overpotential(40 mV@10 mA·cm^(-2))and high exchange current density(3.08 mA·cm^(-2)).Impressively,the assembled flow-cell device with CC@CoNi-LDH anode and CC@CoNi-NC cathode only requires low cell voltage and electricity consumption of 1.6 V and 3.50 kWh per cubic meter of H_(2)(@25 mA·cm^(-2)).

Rare earth metal based DES assisted the VPO synthesis for n-butane selective oxidation toward maleic anhydride

Deep eutectic solvents(DESs) are now considered a new class of ionic liquid analogs that have been generously used in various fields.Herein, vanadium phosphorus oxide(VPO) catalysts are synthesized in combination with a deep eutectic solvent containing rare earth metal(rE-DES), and their catalytic performance in n-butane selective oxidation to produce maleic anhydride(MA) is evaluated. The rE-DES is produced from the interaction of choline chloride(ChCl) and rare earth metal salts(Cerium, Europium, Lanthanum, and Samarium metal salt)(ChCl:rE = 1:0.5–1:3) under mild conditions. It was found that DESs served as structural modifiers and electronic promoters during VPO synthesis. It regulated the chemical state of the catalyst surface, such as the vanadium valence state, acid-base properties, and ratios of V^(4+)/V^(5+),Lat–O/Sur–O and P/V. Various characterization techniques, such as FT-IR, DSC, XRD, SEM, EDS, TEM, Raman, TGA, NH3-TPD, and XPS,were used to examine its physical and chemical characteristics. These characteristics were correlated with the catalytic performance. The VPO catalyst modified by rE-DES showed a significant enhancement of n-butane conversion and MA selectivity while suppressing the selectivity of CO and CO_(2)as well as the CO/CO_(2)ratio compared to the unpromoted VPO catalyst. Especially for Ce-DES-VPO, it increased the n-butane conversion and MA mass yield up to approximately 11% and 10%, respectively. In addition, we evaluated the catalytic performance under different activation atmospheres.

Selective cyclohexane oxidation enhancement by electronic structures regulation of metal-poly(ionic liquid)s

Poly(ionic liquids)(PILs)combined with the macromolecular structure and unique properties of ionic liquids show unlimited potential in catalysis.In this work,a series of metal-based PIL with different ionic ratios were prepared for the selective oxidation of cyclohexane.Characterization analysis reveals that different degrees of ionization could adjust the Co-N sites of the catalysts efficiently,leading to significant changes in their electronic structure,which strongly relate to catalytic performance in oxidation.20.07%cyclohexane conversion and 13.06%cyclohexanone and cyclohexanol(KA oil)yield can be achieved by metal-based PILs that are better than other commercial catalysts.Compared with CoCl_(2),metal-based PILs perform well,with superior conversion and KA oil yield.More interestingly,the catalyst created in this study features a malleable Co-N site,which may potentially have an impact on how oxygen species adsorb and desorb from the catalyst.Therefore,the catalyst studied in this work is used as molecular oxygen for the selective oxidation of cyclohexane to produce KA oil,and its application prospect is promising.

Copper‐doped zinc sulfide nanoframes with three‐dimensional photocatalytic surfaces for enhanced solar driven H_(2) production

Solar‐to‐chemical energy conversion is perceived as one of the most potential solutions to the current energy and environmental crisis,yet requires major scientific endeavors on the development of efficient and sustainable photocatalysts.Remolding the composition and morphology of a semiconductor jointly for the purpose of improving photocatalysis efficiency remains challenging.Herein,we rationally fabricated Cu‐doped ZnS nanoframes via a simple conjunct strategy of substitutional doping,chemical acidic etching,and sulfidation,aiming at enhancing the light utilization and charge separation/transfer efficiency for solar‐light‐driven hydrogen generation.Cu‐doped zeolitic imidazolate framework‐8(ZIF‐8)rhombic dodecahedrons are transformed to hollow Cu‐ZIF‐8 nanoframes converted to Cu‐ZnS nanoframes with three‐dimensional photocatalytic active surfaces via anisotropic chemical etching,which is further converted to Cu‐ZnS nanoframes.By combining the merits of optimal heteroatom doping and frame‐like open architecture,the obtained 1%Cu‐doped ZnS nanoframe exhibits high photocatalytic activity under solar light irradiation with improved hydrogen production rate up to 8.30 mmol h^(–1) g^(–1) and excellent stability in the absence of cocatalysts,which is significantly improved in comparison with those of the bare ZnS and Cu‐ZnS with different morphologies.This work inspired by merging the merits of metal doping and anisotropic chemical etching may shed light on the rational design and fabrication of advanced photocatalysts.

Progress of vanadium phosphorous oxide catalyst for n-butane selective oxidation

The utilization of lighter alkanes into useful chemical products is essential for modern chemistry and reducing the CO_(2)emission.Particularly,n-butane has gained special attention across the globe due to the abundant production of maleic anhydride(MA).Vanadium phosphorous oxide(VPO)is the most effective catalyst for selective oxidation of n-butane to MA so far.Interestingly,the VPO complex exists in more or less fifteen different structures,each one having distinct phase composition and exclusive surface morphology and physiochemical properties such as valence state,lattice oxygen,acidity etc.,which relies on precursor preparation method and the activation conditions of catalysts.The catalytic performance of VPO catalyst is improved by adding different promoters or co-catalyst such as various metals dopants,or either introducing template or structural-directing agents.Meanwhile,new preparation strategies such as electrospinning,ball milling,hydrothermal,barothermal,ultrasound,microwave irradiation,calcination,sol-gel method and solvothermal synthesis are also employed for introducing improvement in catalytic performance.Research in above-mentioned different aspects will be ascribed in current review in addition to summarizing overall catalysis activity and final yield.To analyze the performance of the catalytic precursor,the reaction mechanism and reaction kinetics both are discussed in this review to help clarify the key issues such as strong exothermic reaction,phosphorus supplement,water supplement,deactivation,and air/n-butane pretreatment etc.related to the various industrial applications of VPO.

In situ doping brushite on zinc manganese oxide toward enhanced water oxidation performance: Mimicry of an oxygen‐evolving complex

We report in situ doping of brushite on zinc manganese oxide（ZMO）, fabricated by calcining a Mn（II） oxalate‐impregnated metal‐organic framework. The doping process was conducted in com‐bination with the photocatalytic water oxidation reaction which was catalyzed by ZMO in neutral phosphate‐buffered aqueous solution containing [Ru（bpy）3]^2＋‐Na2S2O8 and calcium（II） triflate salt, exhibiting greatly enhanced water oxidation performance with optimized turnover frequency of 0.18 mmol（O2） mol（Mn）^（–1） s^（–1）. Different analytical techniques indicated that photodeposited calci‐um‐phosphate（CaP） acted as a co‐catalyst to promote the O2 evolution activity of ZMO. This system involved the use of manganese oxide and calcium ion, and the operation was conducted under am‐bient temperature and neutral conditions, thus, it efficiently mimicked the oxygen‐evolving complex in photosystem II.

Microstructure,elastic/mechanical and thermal properties of CrTaO_(4):A new thermal barrier material?

CrTaO_(4)(or Cr_(0.5)Ta_(0.5)O_(2))has been unexpectedly found to play a decisive role in improving the oxidation resistance of Cr and Ta-containing refractory high-entropy alloys(RHEAs).This rarely encountered complex oxide can effectively prevent the outward diffusion of metal cations from the RHEAs.Moreover,the oxidation kinetics of CrTaO_(4)-forming RHEAs is comparable to that of the well-known oxidation resistant Cr_(2)O_(3)-and Al_(2)O_(3)-forming Ni-based superalloys.However,CrTaO_(4)has been ignored and its mechanical and thermal properties have yet to be studied.To fill this research gap and explore the untapped potential for its applications,here we report for the first time the microstructure,mechanical and thermal properties of CrTaO_(4)prepared by hot-press sintering of solid-state reaction synthesized powders.Using the HAADF and ABF-STEM techniques,rutile crystal structure was confirmed and short range ordering was directly observed.In addition,segregation of Ta and Cr was identified.Intriguingly,CrTaO_(4)exhibits elastic/mechanical properties similar to those of yttria stabilized zirconia(YSZ)with Young’s modulus,shear modulus,and bulk modulus of 268,107,and 181 GPa,respectively,and Vickers hardness,flexural strength,and fracture toughness of 12.2±0.44 GPa,142±14 MPa,and 1.87±0.074 MPa·m^(1/2).The analogous elastic/mechanical properties of CrTaO_(4)to those of YSZ has spurred inquiries to lucrative leverage it as a new thermal barrier material.The measured melting point of CrTaO_(4)is 2103±20 K.The anisotropic thermal expansion coefficients areα_(a)=(5.68±0.10)×10^(-6)K^(-1),α_(c)=(7.81±0.11)×10^(-6)K^(-1),with an average thermal expansion coefficient of(6.39±0.11)×10^(-6)K^(-1).The room temperature thermal conductivity of CrTaO_(4)is 1.31 W·m^(-1)·K^(-1)and declines to 0.66 W·m^(-1)·K^(-1)at 1473 K,which are lower than most of the currently well-known thermal barrier materials.From the perspective of matched thermal expansion coefficient,CrTaO_(4)pertains to an eligible thermal barrier material for refractory metals such as Ta,Nb,and RHEAs,and ultrahigh temperature ceramics.As such,this work not only provides fundamental microstructure,elastic/mechanical and thermal properties that are instructive for understanding the protectiveness displayed by CrTaO_(4)on top of RHEAs but also outreaches its untapped potential as a new thermal barrier material.

Thermally activated delayed fluorescence Au-Ag-oxo nanoclusters:From photoluminescence to radioluminescence

Thermally activated delayed fluorescence(TADF)materials have numerous applications in energy conversion and luminescent imaging.However,they are typically achieved as metal-organic complexes or pure organic molecules.Herein,we report the largest Au-Ag-oxo nanoclusters to date,Au_(18)Ag_(26)(R1COO)_(12)(R_(2)C≡C)_(24)(μ_(4)-O)_(2)(μ_(3)-O)_(2)(Au_(18_Ag_(26),where R_(1)=CH_(3-),Ph-,CHOPh-or CF3Ph-;R_(2)=Phor FPh-).These nanoclusters exhibit exceptional TADF properties,including a small S1-T1 energy gap of 55.5 meV,a high absolute photoluminescence quantum yield of 86.7%,and a microseconds TADF decay time of 1.6μs at ambient temperature.Meanwhile,Au18Ag26 shows outstanding stability against oxygen quenching and ambient conditions.Atomic level analysis reveals the strongπ⋯πand C-H⋯πinteractions from the aromatic alkynyl ligands and the enhancement of metal-oxygen-metal interactions by centrally coordinated O^(2−).Modeling of the electronic structure shows spatially separated highest occupied molecular orbital and lowest unoccupied molecular orbital,which promote charge transfer from the ligand shell,predominantly carboxylate ligands,to O^(2−)-embedded metal core.Furthermore,TADF Au-Ag-oxo nanoclusters exhibit promising radioluminescence properties,which we demonstrate for X-ray imaging.Our work paves the way for the design of TADF materials based on large metal nanoclusters for light-emission and radioluminescence applications.

Formation of willow leaf-like structures composed of NH2-MIL68（In） on a multifunctional multiwalled carbon nanotube backbone for enhanced photocatalytic reduction of Cr（VI）

Efficient separation and transfer of photogenerated electron/hole as well as enhanced visible light absorption play essential roles in photocatalytic reactions. To promote the photocatalytic reduction of Cr（VI）, a toxic heavy metal ion, multiwalled carbon nanotube （MWCNT） was introduced as an electron acceptor into NH2-MIL-68（In）. This led to the growth of a willow leaf-like metal-organic framework （MOF） on an MWCNT backbone forming MWCNT/NH2-MIL-68（In） （PL-1）, which showed a highly efficient transfer of photogenerated carriers. Moreover, MWCNT incorporation introduced more mesopores for Cr（VI） diffusion and enhanced the visible light adsorption without lowering the conduction band position. As a result, the photocatalytic kinetic constant of PL-1 was found to be almost three times higher than that of the parent NH2-MIL-68（In）. Thus, growing MOFs on MWCNTs provides a facile and promising solution for effective remediation of environmental pollution by utilizing solar energy. This work provides the first example of using MWCNT/MOF composites for photocatalytic reactions.

Resisting metal aggregation in pyrolysis of MOFs towards highdensity metal nanocatalysts for efficient hydrazine assisted hydrogen production

The preparation of supported high-density metal nanoparticles(NPs)is of great importance to boost the performance in heterogeneous catalysis.Thermal transformation of metal-organic frameworks(MOFs)has been demonstrated as a promising route for the synthesis of supported metal NPs with high metal loadings,but it is challenge to achieve uniform metal dispersion.Here we report a strategy of“spatial isolation and dopant anchoring”to resist metal aggregation in the pyrolysis of MOFs through converting a bulk MOF into dual-heteroatom-containing flower-like MOF sheets(B/N-MOF-S).This approach can spatially isolate metal ions and increase the number of anchoring sites,thus efficiently building physical and/or chemical barriers to cooperatively prevent metal NPs from aggregation in the high-temperature transformation process.After thermolysis at 1,000℃,the B/N-MOFS affords B,N co-doped carbon-supported Co NPs(Co/BNC)with uniform dispersion and a high Co loading of 37.3 wt.%,while untreated bulk MOFs yield much larger sizes and uneven distribution of Co NPs.The as-obtained Co/BNC exhibits excellent electrocatalytic activities in both hydrogen evolution and hydrazine oxidation reactions,only a voltage of 0.617 V at a high current density of 100 mA·cm^(−2)is required when applied to a two-electrode overall hydrazine splitting electrolyzer.

Carbon-based nanoarrays embedded with Ce-doped ultrasmall Co_(2)P nanoparticles enable efficient electrooxidation of 5-hydroxymethylfurfural coupled with hydrogen production

The electrooxidation of 5-hydroxymethylfurfural(HMFOR)not only offers a green route to attain high-value 2,5-furandicarboxylic acid(FDCA)from biomass,but also is considered as a promising approach to replace the kinetically sluggish OER for future hydrogen production.Herein,we report the construction and structural optimization of Ce-doped ultrasmall Co_(2)P nanoparticles(NPs)in carbon-based nanoarrays to boost HER-coupled HMFOR.We demonstrate that the electronic structure of Co-based electrocatalysts can be positively regulated by Ce doping and the optimized Ce-Co_(2)P-based electrocatalyst only require a low voltage of 1.20 V vs.RHE to achieve 10 m A cm^(-2)for HMFOR with an excellent FDCA Faraday efficiency(FEFDCA)of 98.5%,which are superior to its Ce-free counterpart(1.29 V vs.RHE;FEFDCA=83.9%).When being assembled into a HERcoupled HMFOR system,this bifunctional electrocatalyst can achieve 50 m A cm^(-2)with an ultralow voltage of 1.46 V,which is reduced by 210 m Vas compared with that of its Ce-free counterpart(1.67 V).Quasi-operando experiments and DFTcalculations further reveal the significant roles of Ce doping in promoting the charge transfer between active sites and HMF,and reducing the free energy barrier of intermediate(^(*)HMFCA)dehydrogenation.This study provides new insights into the underlying mechanisms of Ce doping into metal phosphides for boosting HER-coupled HMFOR,developing a facile methodology to construct efficient electrocatalysts for energy storage/conversion systems.

Size Effects of Atomically Precise Gold Nanoclusters in Catalysis

The emergence of ligand-protected,atomically precise gold nanoclusters(NCs)in recent years has attracted broad interest in catalysis due to their well-defined atomic structures and intriguing properties.Especially,the precise formulas of NCs provide an opportunity to study the size effects at the atomic level without complications by the polydispersity in conventional nanoparticles that obscures the relationship between the size/structure and properties.Herein,we summarize the catalytic size effects of atomically precise,thioate-protected gold NCs in the range of tens to hundreds of metal atoms.The catalytic reactions include electrochemical catalysis,photocatalysis,and thermocatalysis.With the precise sizes and structures,the fundamentals underlying the size effects are analyzed,such as the surface area,electronic properties,and active sites.In the catalytic reactions,one or more factors may exert catalytic effects simultaneously,hence leading to different catalytic-activity trends with the size change of NCs.The summary of literature work disentangles the underlying fundamental mechanisms and provides insights into the size effects.Future studies will lead to further understanding of the size effects and shed light on the catalytic active sites and ultimately promote catalyst design at the atomic level.

Encapsulation of ultrafine Pd nanoparticles within the shallow layers of UiO-67 for highly efficient hydrogenation reactions

Metal-organic frameworks(MOFs)have been used to encapsulate active metal nanoparticles(MNPs)to fabricate MNPs@MOFs composites with high catalytic efficiencies.However,the diffusion of reactants and the accessibility of MNPs located in the center of MOFs may be hindered due to the inherent microporous structures of MOFs,which would affect the catalytic activities of MNPs.Herein,we report a solvent assisted ligand exchange-hydrogen reduction(SALE-HR)strategy to selectively encapsulate ultrafine MNPs(Pd or Pt)within the shallow layers of a MOF,i.e.,UiO-67.The particle sizes of the encapsulated MNPs and the thickness of the MNPs-embedded layers can be adjusted easily by controlling the SALE conditions(e.g.time and temperature).Crucially,the LE-Pd@UiO-80-0.5 composite with the thinnest Pd-embedded layers displays remarkable catalytic efficiency with a high turnover frequency(TOF)value of 600 h^-1towards hydrogenation of nitrobenzene under 1 atm H_2at room temperature.The results indicate that the catalytic efficiency and the utilization of MNPs can be enhanced by compactly encapsulating MNPs within the shallow layers of MOFs as close to their outer surfaces as possible,owing to the short masstransfer distance and enhanced accessibility of overall MNPs.

Scalable synthesis of multi-shelled hollow N-doped carbon nanosheet arrays with confined Co/CoP heterostructures from MOFs for pH-universal hydrogen evolution reaction

Developing low-cost but efficient hydrogen evolution reaction(HER)electrocatalysts over whole pH values is a significant but daunting task for the large-scale application of electrochemical hydrogen production.Herein,we develop,for the first time,a scalable MOF-assisted strategy for the fabrication and microstructural optimization of multi-shelled hollow N-doped carbon nanosheet arrays with confined Co/CoP heterostructures on carbon cloth(Co/CoP@NC/CC)for boosting HER performances.The key to this strategy is the step-by-step epitaxial growth of unprecedented multilayer ZIF-L arrays on carbon cloth,which are subsequently pyrolyzed and controllably phosphorized to achieve the precise control over the shell number and nanoarchitectures of the Co/CoP@NC/CC.Impressively,the HER performances can be significantly enhanced by increasing hollow shell number,and the optimal triple-shelled hollow Co/CoP@NC/CC exhibits low overpotentials of 86,78 and 145 mV in acidic,alkaline and neutral media to deliver a current density of 10 mA cm^(-2),respectively,ranking as one of the best Co-based HER electrocatalysts over whole pH values.Further DFT calculations suggest that the Co/CoP heterostructures can effectively boost the cleavage of H–OH to generate protons and optimize the adsorption energy of hydrogen(ΔG_(H*)),which,together with the large electrode/electrolyte interface and accelerated charge/mass transfer of multi-shelled hollow array structure as well as the good conductivity and dispersity,are responsible for the remarkably improved HER performances.This study not only provides a new toolbox for enriching the family of multi-shelled nanoarchitecture materials,but also points out a general and effective route to develop highly efficient self-supported electrode materials for energy-related applications and beyond.

Wind power forecasting based on new hybrid model with TCN residual modification

Wind energy has been widely utilized to alleviate the shortage of fossil resources.When wind power is integrated into the power grid on a large scale,the power grid’s stability is severely harmed due to the fluctuating and intermittent properties of wind speed.Accurate wind power forecasts help to formulate good operational strategies for wind farms.A short-term wind power forecasting method based on new hybrid model is proposed to increase the accuracy of wind power forecast.Firstly,wind power time series are separated using the complete ensemble empirical mode decomposition with adaptive noise method to obtain multiple components,which are then predicted using a support vector regression machine model optimized through using the grid search and cross validation(GridSearchCV)algorithm.Secondly,a residual modification model based on temporal convolutional network is constructed,and variables with high correlation are selected as the input features of the model to predict the residuals of wind power.Finally,the prediction accuracy of the proposed method is compared to other models using the actual wind power data of the wind farm to demonstrate the validity of the described method,and the results reveal that the proposed method has better prediction performance.

Prediction model of microwave calcining of ammonium diuranate using incremental improved back-propagation neural network

The incremental improved Back-Propagation （BP） neural network prediction model using the Levenberg-Marquardt algorithm based on optimizing theory is put forward, which can solve the problems existing in the process of calcinations for ammonium diuranate （ADU） by microwave heating, such as long testing cycle, high testing quan- tity, difficulty of optimization for process parameters. Many training data probably were offered by the way of increment batch and the limitation of the system mem- ory could make the training data infeasible when the sample scale was large. The prediction model of the nonlinear system is built, which can effectively predict the experiment of microwave calcining of ADU, and the incremental improved BP neural network is very useful in overeoining the local minimum problem, finding the global optimal solution and accelerating the convergence speed.

Facet-selective growth of MOF-on-MOF heterostructures enables etching-free synthesis of highly-open Co/N-doped carbon nanoframes for efficient catalysis

Highly-open nanoframe structures consisting of interconnected and exposed ridges are highly desirable for achieving efficient catalysis,but preparing them by a facile etching-free methodology is still a very daunting task.Herein,we propose a novel metal-organic framework(MOF)-assisted and etching-free strategy for the construction of Co/N-doped carbon nanoframes with highly-open and precisely-controllable structures.This strategy is based on the face-selective epitaxial growth of ZIF-67 on the 36{110}facets of 72-facet ZIF-8 to form an unprecedented anisotropic ZIF-67-on-ZIF-8 heterostructure,which is subsequently pyrolyzed under Ar atmosphere to realize a solid-to-frame transformation.The highly-open nanoframe structure enables the substrates to readily penetrate into the catalyst interior and thereby create additional exposed active sites,which together with the good mass transport,high atomic utilization and increased surface area are responsible for its remarkably enhanced catalytic activity for the biomass valorisation when compared with its solid and closed hollow counterparts.This study could shed valuable insights into the design and preparation of various highly-open nanoframes with abundant exposed active species by using an etching-free strategy for efficient catalysis and beyond.

N-doped nanocarbon embedded in hierarchically porous metal-organic frameworks for highly efficient CO_(2) fixation

The rational integration of multi-functional components with metal–organic frameworks(MOFs) to form MOF-based catalysts can often afford enhanced catalytic activity for specific reactions. Herein, we propose a novel strategy for the synthesis of hierarchically porous MOFs(e.g., MIL-101)-encapsulated N-doped nanocarbon(CN@MIL) by controlled pyrolysis of ionic liquids@MIL-101 precursors(ILs@MIL). The obtained CN@MIL composites not only possess abundant enlarged mesopores,but also show multi-active sites without the sacrifice of their structure stability. The CN@MIL can efficiently facilitate the mass transfer of substrates, exhibiting excellent catalytic performance in the synthesis of cyclic carbonates from epoxides and CO_(2) under mild and co-catalyst-free conditions(i.e., 90 ℃ and ambient pressure of CO_(2)). Furthermore, the multi-active Lewis acid sites and nucleophilic sites(Br ions) as well as the strong affinity of catalysts toward CO_(2)also contribute to the excellent catalytic activity of the CN@MIL. This study might open a new avenue for the rational design of MOF-based composites by employing ILs@MOF as precursors for advanced heterogeneous catalysis.