Coupling of Adhesion and Anti‑Freezing Properties in Hydrogel Electrolytes for Low‑Temperature Aqueous‑Based Hybrid Capacitors

Solid-state zinc-ion capacitors are emerging as promising candidates for large-scale energy storage owing to improved safety,mechanical and thermal stability and easy-to-direct stacking.Hydrogel electrolytes are appealing solid-state electrolytes because of eco-friendliness,high conductivity and intrinsic flexibility.However,the electrolyte/electrode interfacial contact and anti-freezing properties of current hydrogel electrolytes are still challenging for practical applications of zinc-ion capacitors.Here,we report a class of hydrogel electrolytes that couple high interfacial adhesion and anti-freezing performance.The synergy of tough hydrogel matrix and chemical anchorage enables a well-adhered interface between hydrogel electrolyte and electrode.Meanwhile,the cooperative solvation of ZnCl2 and LiCl hybrid salts renders the hydrogel electrolyte high ionic conductivity and mechanical elasticity simultaneously at low temperatures.More significantly,the Zn||carbon nanotubes hybrid capacitor based on this hydrogel electrolyte exhibits low-temperature capacitive performance,delivering high-energy density of 39 Wh kg^(-1)at-60°C with capacity retention of 98.7%over 10,000 cycles.With the benefits of the well-adhered electrolyte/electrode interface and the anti-freezing hydrogel electrolyte,the Zn/Li hybrid capacitor is able to accommodate dynamic deformations and function well under 1000 tension cycles even at-60°C.This work provides a powerful strategy for enabling stable operation of low-temperature zinc-ion capacitors.

Porous heterostructure of graphene/hexagonal boron nitride as an efficient electrocatalyst for hydrogen peroxide generation

Compared with the traditional heteroatom doping,employing heterostructure is a new modulating approach for carbon-based electrocatalysts.Herein,a facile ball milling-assisted route is proposed to synthesize porous carbon materials composed of abundant graphene/hexagonal boron nitride(G/h-BN)heterostructures.Metal Ni powder and nanoscale h-BN sheets are used as a catalytic substrate/hard template and“nucleation seed”for the formation of the heterostructure,respectively.As-prepared G/h-BN heterostructures exhibit enhanced electrocatalytic activity toward H_(2)O_(2) generation with 86%-95%selectivity at the range of 0.45-0.75 V versus reversible hydrogen electrode(RHE)and a positive onset potential of 0.79 versus RHE(defined at a ring current density of 0.3 mA cm^(-2))in the alkaline solution.In a flow cell,G/h-BN heterostructured electrocatalyst has a H_(2)O_(2) production rate of up to 762 mmol g_(catalyst)^(-1) h^(-1) and Faradaic efficiency of over 75%during 12 h testing,superior to the reported carbon-based electrocatalysts.The density functional theory simulation suggests that the B atoms at the interface of the G/h-BN heterostructure are the key active sites.This research provides a new route to activate carbon catalysts toward highly active and selective O_(2)-to-H_(2)O_(2) conversion.

For more and purer hydrogen-the progress and challenges in water gas shift reaction

The water gas shift(WGS) reaction is a standard reaction that is widely used in industrial hydrogen production and removal of carbon monoxide. The improved catalytic performance of WGS reaction also contributes to ammonia synthesis and other reactions. Advanced catalysts have been developed for both high and low-temperature reactions and are widely used in industry. In recent years, supported metal nanoparticle catalysts have been researched due to their high metal utilization. Low-temperature catalysts have shown promising results, including high selectivity, high shift rates, and higher activity potential. Additionally, significant progress has been made in removing trace CO through the redox reaction in electrolytic cell. This paper reviews the development of WGS reaction catalysts, including the reaction mechanism, catalyst design, and innovative research methods. The catalyst plays a crucial role in the WGS reaction, and this paper provides an instant of catalyst design under different conditions. The progress of catalysts is closely related to the development of advanced characterization techniques.Furthermore, modifying the catalyst surface to enhance activity and significantly increase reaction kinetics is a current research direction. This review goals to stimulate a better understanding of catalyst design, performance optimization, and driving mechanisms, leading to further progress in this field.

An improved theoretical procedure for the pore-size analysis of activated carbon by gas adsorption

Amorphous carbon materials play a vital role in adsorbed natural gas(ANG) storage. One of the key issues in the more prevalent use of ANG is the limited adsorption capacity, which is primarily determined by the porosity and surface characteristics of porous materials. To identify suitable adsorbents, we need a reliable computational tool for pore characterization and, subsequently, quantitative prediction of the adsorption behavior. Within the framework of adsorption integral equation(AIE), the pore-size distribution(PSD) is sensitive to the adopted theoretical models and numerical algorithms through isotherm fitting. In recent years, the classical density functional theory(DFT) has emerged as a common choice to describe adsorption isotherms for AIE kernel construction. However,rarely considered is the accuracy of the mean-field approximation(MFA) commonly used in commercial software. In this work, we calibrate four versions of DFT methods with grand canonical Monte Carlo(GCMC) molecular simulation for the adsorption of CH_4 and CO_2 gas in slit pores at 298 K with the pore width varying from 0.65 to 5.00 nm and pressure from 0.2 to 2.0 MPa. It is found that a weighted-density approximation proposed by Yu(WDA-Yu) is more accurate than MFA and other non-local DFT methods. In combination with the trapezoid discretization of AIE, the WDA-Yu method provides a faithful representation of experimental data, with the accuracy and stability improved by 90.0% and 91.2%, respectively, in comparison with the corresponding results from MFA for fitting CO_2 isotherms. In particular, those distributions in the feature pore width range(FPWR)are proved more representative for the pore-size analysis. The new theoretical procedure for pore characterization has also been tested with the methane adsorption capacity in seven activated carbon samples.

Metallurgical pyrolysis toward Co@Nitrogen-doped carbon composite for lithium storage

Elemental state matter-heteroatom-doped carbon composites are of great importance for the development of anode in lithium ion batteries(LIBs).In this article,metal–organic frameworks(MOFs)are adopted as precursor to prepare Co composites via metallurgical pyrolysis under controllable conditions.The obtained nitrogen-doped porous carbon-Co nanocomposite possesses core–shell structure(Co@C–N).Co@C–N exhibits the best Li storage performances as anode active matter.After the 200th cycles at current density of 0.2 A g^(-1),a reversible capacity of 870 mAh g^(-1)is retained.A reversible capacity of 275 mAh g^(-1)still maintains with 5 A g^(-1).Co@C–N presents a high reversible capacity with excellent cycle stability.Considering the corresponding experimental and theoretical results,the Co0-based N-doped porous carbon composite is proposed to work as LIBs anode matter.These results provide a new design idea for electrode matters of metallic ion battery,and demonstrate that MOFs pyrolysis is an effective method for the construction of elemental state anode materials.

Co_(2)N Nanoparticles Anchored on N-Doped Active Carbon as Catalyst for Oxygen Reduction Reaction in Zinc–Air Battery

The development of efficient catalytic electrode toward oxygen reduction reaction(ORR)is still a great challenge for the wide use of zinc–air batteries.Herein,Co_(2)N nanoparticles(NPs)anchored on N-doped carbon from cattail were verified with excellent catalytic performances for ORR.The onset and half-wave potentials over the optimal catalyst reach to 0.96 V and 0.84 V,respectively.Current retention rates of 96.8%after 22-h test and 98.8%after running 1600 s were obtained in 1 M methanol solution.Density functional theory simulation proposes an apparently increased electronic states of Co_(2)N in N-doped carbon layer close to the Fermi level.Higher charge density,favorable adsorption,and charge transfer of intermediates originate from the coexistence of Co_(2)N NPs and N atoms in carbon skeleton.The superior catalytic activity of composites also was confirmed in zinc–air batteries.This novel catalytic property and controllable preparation approach of Co_(2)Ncarbon composites provide a promising avenue to fabricate metal-containing catalytically active carbon from biomass.

Kinetics and Mechanism of the Uncatalyzed Esterification of Acid-Rich Oil with Glycerol

In this paper, non-catalytic high temperature deacidification process of glycerol rich in acid oil was studied. Through orthogonal experiment, the primary and secondary order of influencing factors was temperature, glycerol dosage and reaction time, and the optimal process conditions were further verified: The ratio of fatty acid to glycerol is 1:1.2, the reaction temperature is 240°C, and the acid value can be reduced to 1.66 mg KOH/g for 2 h. In addition, the activation energy of the reaction was 54.93 kJ/mol by kinetic study. Combined with the K1 value of each reaction, it was confirmed that the temperature rise was conducive to the progress of the reaction. Finally, the high temperature ionization theory of glycerol is put forward, and the mechanism of auto-catalyzed deacidification reaction of glycerol is deduced by using this theory. This theory not only explains this study, but also perfectly explains the slow reaction time of low glycerol dosage.

A process insight into production of ethyl levulinate via a stepwise fractionation

Ethyl levulinate(EL)is a key biomass-derived compounds due to its socio-economic benefits for the synthesis of commodity chemicals.Herein,we proposed an efficient one-step bamboo conversion to EL in ethanol,and a novel stepwise fractionation to purify EL and lignocellulose degradation products.A proton acid,due to its high catalytic efficiency,yielded 26.65%EL in 120 min at 200℃.The productions of ethyl glucoside and 5-ethoxymethylfurfural were analyzed in terms of by-products formation.To the best of our knowledge,there is no single report on catalyst for one step synthesis of EL directly from bamboo,as well as a stepwise fractionation to purify EL.Due to similar physiochemical properties in each fraction,the platform molecules could broaden a new paradigm of bamboo biomass utilization for renewable energy and value-added biochemicals.In addition,glucose,ethyl glucoside,corn starch,and microcrystalline cellulose were also investigated as substrates,so that the reaction intermediates of this one-pot procedure were identified and a possible reaction mechanism was proposed.

Fabricating pyridinic N-B sites in porous carbon as efficient metal-free electrocatalyst in conversion CO_(2)into CH_(4)

Electrochemical reduction of CO_(2)(CO_(2)RR)to value-added chemicals is an attractive strategy for greenhouse gas mitigation and carbon recycle.Carbon material is one of most promising electrocatalysts but its product selectivity is limited by few modulating approaches for active sites.Herein,the predominant pyridinic N-B sites(accounting for 80%to all N species)are fabricated in hierarchically porous structure of graphene nanoribbons/amorphous carbon.The graphene nanoribbons and porous structure can accelerate electron and ion/gas transport during CO_(2)RR,respectively.This carbon electrocatalyst exhibits excellent selectivity toward CO_(2)reduction to CH_(4)with the faradaic efficiency of 68%at−0.50 V vs.RHE.As demonstrated by density functional theory,a proper adsorbed energy of∗CO and∗CH_(2)O are generated on the pyridinic N-B site resulting into high CH_(4)selectivity.Therefore,this study provides a novel method to modulate active sites of carbon-based electrocatalyst to obtain high CH_(4)selectivity.

Advances and challenges of cellulose functional materials in sensors

As the most abundant natural polymer material on the earth,cellulose is a promising sustainable sensing material due to its high mechanical strength,excellent biocompatibility,good degrada-tion,and regeneration ability.Considering the inherent advantages of cellulose and the success of modern sensors,applying cellulose to sensors has always been the subject of considerable investigation,and significant progress has been made in recent decades.Herein,we reviewed the research progress of cellulose functional materials(CFMs)in recent years.According to the different sources of cellulose,the classification and preparation methods for the design and func-tionalization of cellulose were summarized with the emphasis on the relationship between their structure and properties.Besides,the applications of advanced sensors based on CFMs in recent years were also discussed.Finally,the potential challenges and prospects of the development of sensor based on CFMs were outlined.

Establishment of green graphite industry:Graphite from biomass and its various applications

Resource-and energy-efficient biomass exploitation for green graphite production is one of the most effective strategies for satisfying graphite demand while minimizing energy consumption and carbon emissions.This study investigated green graphite production from biomass waste and its applications to establish a green graphite industry.Biomass pyrolysis and catalytic graphitization of biochar were studied first to produce green graphite.The optimized green graphite exhibited a reversible capacity of 264 mA h/g and 97%capacity retention over 100 cycles in a half-cell.Green graphite electrodes with a resistivity lower than 5μΩm were fabricated by using organic fraction bio-oil as a green binder.Other green graphite applications,including printing,conductive printing,pencils,and refractories,were also achieved.The overall process of graphite anode and electrode synthesis from biomass waste and short-rotation energy crops was modeled.Approx.95 kg of battery graphite or 109 kg of metallurgical graphite electrodes can be produced per ton of biomass with low primary energy consumption and carbon footprint.Prominently,the modeling result and life cycle assessment demonstrated that,for the production of battery graphite from biomass waste,net-negative-CO_(2)emissions(−0.57 kg CO_(2)-eq/kg graphite powders)with net-negative-primary energy consumption(−28.31 MJ/kg graphite powders)was achieved.

Wood-derived integrated air electrode with Co-N sites for rechargeable zinc-air batteries

The sluggish reaction kinetics in oxygen reduction reaction(ORR)is one of the bottlenecks in next generation energy conversion systems.The integrated design strategy based on simultaneously constructing active sites and forming porous carbon network will address this concern by facilitating charge exchange,mass transfer and electron transportation.In this article,a three-dimensional integrated air electrode(Co-N@ACS)containing Co-N sites and hierarchically porous carbon is fabricated via growth of Co-doped ZIF-8 in activated wood substrate and synchronous pyrolysis.The optimized integrated air electrodes exhibit ultrahigh ORR activity(E_(1/2)=0.86 V).Co-N sites provide outstanding ORR activity,and hierarchically porous structures facilitate oxygen diffusion and electrolyte penetration.Aqueous zinc-air battery assembled with Co-N@ACS possesses open-circuit voltage of 1.46 V,peak power density of 155 mW cm^(-2) and long-term stability of 540 cycles(180 h).Solid-state zinc-air battery assembled with Co-N@ACS shows open-circuit voltage up to 1.36 V and low charge-discharge voltage gap(0.8 V).This design strategy paves the way for the conversion of wood biomass to integrated air electrodes and catalytically active carbon for next generation energy storage and conversion devices.

CFD simulation of jet behaviors in a binary gas-solid fluidized bed:comparisons with experiments

Based on the experimental observation of the fluidization characteristics of solid mixtures(resin and rapeseed)with different densities and sizes,the jet behaviours of the binary system are simulated in a twodimensional jetting fluidized bed 0.30m in width and 2.00m in height.A simple mathematical model,by introducing two additional force terms in both gas and particle phase momentum equations of Gidaspow’s inviscid two-fluid model,is used to explore the effects of jet gas velocity and mixture combination on the jet penetration depth in the fluidized bed with a binary system.Experimental results show that there is a fluidization velocity interval(u_(if)-u_(ff))for the resin-on-rapeseed(flotsam-on-jetsam)segregated bed.The simulated jet penetration depth increases with the increase of jet gas velocity and the volume fraction of the flotsam(resin),which is in fair agreement with experimental data.The above findings show that the hydrodynamic model of Brandani and Zhang(2006),by introducing the average physical properties from Goossens et al.(1971),can be used to predict the jet behaviors of a well-mixing binary system.

Review of the direct thermochemical conversion of lignocellulosic biomass for liquid fuels

Increased demand for liquid transportation fuels, environmental concerns and depletion of petroleum resources requires the development of efficient conversion technologies for production of second-generation biofuels from non-food resources. Thermochemical approaches hold great potential for conversion of lignocellulosic biomass into liquid fuels. Direct thermochemical processes convert biomass into liquid fuels in one step using heat and catalysts and have many advantages over indirect and biological processes, such as greater feedstock flexibility, integrated conversion of whole biomass, and lower operation costs. Several direct thermochemical processes are employed in the production of liquid biofuels depending on the nature of the feedstock properties: such as fast pyrolysis/liquefaction of lignocellulosic biomass for bio-oil, including upgrading methods, such as catalytic cracking and hydrogenation. Owing to the substantial amount of liquid fuels consumed by vehicular transport, converting biomass into drop-in liquid fuels may reduce the dependence of the fuel market on petroleumbased fuel products. In this review, we also summarize recent progress in technologies for large-scale equipment for direct thermochemical conversion. We focus on the technical aspects critical to commercialization of the technologies for production of liquid fuels from biomass,including feedstock type, cracking catalysts, catalytic cracking mechanisms, catalytic reactors, and biofuel properties. We also discuss future prospects for direct thermochemical conversion in biorefineries for the production of high grade biofuels.

Liquefaction of bamboo biomass and production of three fractions containing aromatic compounds

Depolymerization of lignin to produce value-added aromatic monomers has attracted increasing attention since these monomers can be used as phenol replacement in production of phenolic resins.Here a one-pot depolymerization of bamboo lignin was investigated to obtain aromatic platforms with low molecular weight using acidic catalyst and ethanol.Three fractions(1#,2#,and 3#)containing different molecular weight distributions of aromatic compounds could be efficiently extracted using water-organic solvent system via a stepwise fractionation process by gradual removal of solvent.The fractions distribution was found to be primarily dependent on the reaction temperature and time.When the temperature was increased from 160°C to 200°C,the yield of fractions containing aromatic products increased significantly from 19.1 wt%to 27 wt%,the same change trend was found by changing the time,and the yield of aromatic products increased from 22.4%to 26.7%with an increase of time from 10 min to 30 min.The bioproducts were characterized by using gas chromatography/mass spectrometry(GC-MS),gel permeation chromatography(GPC)and two-dimensional heteronuclear single-quantum coherence(2D HSQC NMR).As evidenced by GC-MS spectra,the three fractions were mainly comprised of phenolic derivatives,and the relative contents of phenolic compounds took up about 80%of the total area of each fraction.With the similar physiochemical properties of the fractions,aromatic platforms could provide a new paradigm of bamboo lignin utilization for renewable energy and value-added biochemicals.

The modulating effect of N coordination on single-atom catalysts researched by Pt-N_(x)-C model through both experimental study and DFT simulation

N-doped carbon-based single-atom catalysts(NC-SACs) are widely researched in various electrochemical reactions due to high metal atom utilization and catalytic activity.The catalytic activity of NC-SACs originates from the coordinating structure between single metal site(M) and the doped nitrogen(N) in carbon matrix by forming M-N_(x)-C structure(1≤x≤4).The M-N4-C structure is widely considered to be the most stable and effective catalytic site.However,there is no in-depth research for the "x" modulation in Pt-Nx-C structure and the corresponding catalytic properties.Herein,atomically dispersed Pt on N-doped carbon(Pt-NC) with Pt-Nx-C structure(1≤x≤4),as a research model,is fabricated by a ZIF-8 template and applied to catalytic oxygen reduction.Different carbonization temperatures are used to control N loss,and then modulate the N coordination of Pt-Nx-C structure.The Pt-NC has the predictable low half-wave potential(E_(1/2)) of 0.72 V vs RHE compared to the Pt/C 20% of 0.81 V due to low Pt content.Remarkably,the Pt-NC shows a high onset potential(1.10 V vs RHE,determined for j=-0.1 mA cm^(2)) and a high current density of 5.2 mA cm^(-2),more positive and higher than that of Pt/C 20%(0.96 V) and 4.9 mA cm^(-2),respectively.As the structural characterization and DFT simulation confirmed,the reducing PtN coordination number induces low valence of Pt atoms and low free energy of oxygen reduction,which is responsible for the improved catalytic activity.Furthermore,the Pt-NC shows high mass activity(172 times higher than that of Pt/C 20%),better stability and methanol crossover resistance.

Production of Itaconic Acid Through Microbiological Fermentation of Inexpensive Materials

Itaconic acid(IA)is a precursor of various chemicals,which has been on the US Department of Energy’s list of the top 12 platform chemicals that can potentially be produced from biomass.The IA is mainly produced through a bio-fermentation method with sugar as raw material.However,the high cost and low yield restrict the industrial application of the IA.This review summarized research advances in the IA production from alternative substrates.In particular,the types of substrates as well as existing problems in the IA fermentation,strain breeding,and process regulation were discussed.And it is pointed that decreasing the price of the IA through use of alternative substrates and increasing the titer of the IA through genetic engineering should be further focused on to support the industrialization of the IA.