Recent Research Progress of Paper-Based Supercapacitors Based on Cellulose

In recent years,paper-based functional materials have received extensive attention in the field of energy storage due to their advantages of rich and adjustable porous network structure and good flexibility.As an important energy storage device,paper-based supercapacitors have important application prospects in many fields and have also received extensive attention from researchers in recent years.At present,researchers have modified and regulated paper-based materials by different means such as structural design and material composition to enhance their electrochemical storage capacity.The development of paper-based supercapacitors provides an important direction for the development of green and sustainable energy.Therefore,it is of great significance to summarize the relevant work of paper-based supercapacitors for their rapid development and application.In this review,the recent research progress of paper-based supercapacitors based on cellulose was summarized in terms of various cellulose-based composites,preparation skills,and electrochemical performance.Finally,some opinions on the problems in the development of this field and the future development trend were proposed.It is hoped that this review can provide valuable references and ideas for the rapid development of paper-based energy storage devices.

Integrated Forest Biorefinery:Value-added Utilization of Dissolved Organics in the Prehydrolysis Liquor of Prehydrolysis Kraft (PHK) Dissolving Pulp Production Process

The concept of integrated forest biorefineries(IFBRs) has gained significant interest.The prehydrolysis kraft(PHK) dissolving pulp production process is a suitable example of IFBR concept for the production of dissolving pulp and utilization of dissolved hemicelluloses,acetic acid,and lignin in the prehydrolysis liquor(PHL).This review paper highlights recent progress related to the recovery and utilization of dissolved organics(e.g.,hemicelluloses,acetic acid,and lignin) in the PHL of the PHK dissolving pulp production process.Integrated multi-step recovery and separation processes have been developed for this purpose to accommodate the complex nature of the PHL.Potential products,including xylan-based compounds,acetic acid,and lignin,are also discussed in detail.

Green and Effective Ammonium Carbonate-assisted Process for Drying Hemicellulose Obtained through Alkali Extraction of Bleached Bamboo Kraft Pulp

Hemicellulose has a wide range of applications,including that as an emulsifier for the food industry and raw material for the synthesis of bioethanol/biochemicals and biodegradable films.Hemicellulose is usually present as a spent liquor,such as the prehydrolysis liquor of the prehydrolysis kraft dissolving pulp production process and the alkali extraction liquor of the cold caustic extraction of pulp fibers.Due to its dilute nature,hemicellulose needs to be dried for practical utilization,and this is challenging.In this study,cellulose and hemicellulose in a bleached bamboo kraft pulp were separated using an alkali extraction process.Hemicellulose obtained from the extraction liquor was dried by an ammonium carbonate-assisted drying process.The effects of drying time and drying temperature were determined.Structure of the hemicellulose obtained by the ammonium carbonate-assisted drying process was similar to that of original hemicellulose,as revealed by detailed Fourier transform infrared and X-ray diffraction analyses.The novel drying method was more energy efficient and required a shorter drying time than the conventional freeze drying method,and the excellent solubility in alkaline solutions favored the chemical modification of hemicellulose.The dried hemicellulose can be used as a renewable raw material for the preparation of hydrogels and other substances such as bioethanol/biochemicals and biodegradable films.

NIR-responsive Collagen-based Sponge Coated with Polydimethylsiloxane/Candle Soot for Oil-Water Separation

To fabricate an oil-water separation material that is rich in source,eco-friendly,and responsive,in this study,we successfully developed a collagen-based sponge for application to oil-water separation based on a green and facile strategy.In this design,widely-available collagen(COL)was used as the substrate:it was immersed in polydimethylsiloxane(PDMS)suspension with candle soot(CS)nanoparticles,followed by hot curing.The resultant sponge(CS/PDMS-COL)possessed good hydrophobicity with a water contact angle of 148.3°under a low PDMS concentration of 2%.The results from field emission scanning electron microscope,Fourier transform infrared spectrometer,X-ray photoelectron spectrometer,and X-ray diffractometry demonstrated the successful coating of CS and PDMS on the surface of COL substrate.The CS/PDMS-COL can adsorb eight oils,with the adsorption capacity for trichloromethane reaching 95 g/g.With benzene as the target adsorbent,the separation efficiency was maintained at no less than 95%even after recycling 20 times.CS/PDMS-COL was also used to separate oil-in-water emulsion.Moreover,the sponge killed bacteria effectively due to its excellent near-infrared photothermal responsiveness.This study provides new insight into the preparation of facile oil-water separation materials based on naturally occurring biomaterials effortlessly.

Upgrading Paper-grade Softwood Kraft Pulp to Dissolving Pulp by Cold Caustic Extraction

Cold caustic extraction has potential applications in the production of dissolving-grade pulps due to its ability to selectively remove hemicellulose from lignocellulosic materials. In this study,we demonstrate the conversion of paper-grade kraft pulp into dissolving pulp by a single-stage cold caustic extraction. Under the extraction conditions of 12 wt% NaOH lye,11% pulp consistency,a temperature of 35℃,and 2 h,a paper-grade softwood kraft pulp was purified to high-grade dissolving pulp with 97. 1% α-cellulose content,1. 2% pentosane content,and narrowed molecular weight distribution. The resulting extraction filtrate was concentrated by nano-filtration to obtain the hemicellulose content of 59. 0 g / L,while the permeate was a clear Na OH solution with 10. 9 wt% concentration. A process configuration was also proposed,integrating this cold caustic extraction process with existing pulp and paper production and multi-purpose utilization of the extraction filtrate.

Celulose Paper-based Strapping Products for Green/Sustainable Packaging Needs

Paper products such as corrugated paperboards are the most common green packaging materials, which are renewable, sustainable, recyclable and biodegradable. However, the plastic or metal straps used to secure the carton boxes are not so green. At the end of packaging, the carton boxes can be recycled, but the plastic/metal straps have to be sorted out for disposal separately. This review focuses on: 1) the global trend of green packaging;2) conventional plastic/metal strapping materials for carton boxes;3) conventional market pulp baling with steel wire as the tying materials;4) cellulose fiber-based materials for strapping market pulp bales and carton boxes. New generation of cellulose paper straps are being developed for more challenging applications with superior strength properties and repulpability.

Hydrogenation of Pyrolysis Oil from Loblolly Pine Residue

Loblolly pine residue prepared with and without zeolite ZSM-5 was pyrolyzed at 600℃ and the pyrolysis oil was hydrogenated using formic acid as a hydrogen source, in the presence of a Ru/activated carbon catalyst. As indicated by the pyrolysis yield, addition of the zeolite ZSM-5 increased the yield of light oil but decreased the yield of heavy oil. The pyrolysis oils were analyzed by 13C-,31P-,19F-nuclear magnetic resonance(NMR), and heteronuclear single quantum coherence or heteronuclear single quantum correlation nuclear magnetic resonance(HSQC-NMR), demonstrating that the zeolite ZSM-5 can efficiently induce decarboxylation reactions and decrease the content of aliphatic hydroxyl groups in the heavy oil by 57%.After hydrogenation of the pyrolysis oil, the aromatic carbon content decreased by 78%, with a significant increase in the aliphatic carbon content.

Multi-layer hierarchical cellulose nanofibers/carbon nanotubes/vinasse activated carbon composite materials for supercapacitors and electromagnetic interference shielding

Developing porous self-supporting electrodes with excellent conductivity,good mechanical properties,and high electrochemical activity is crucial for constructing electrode materials with lightweight,ultra-thin,flexible,and high capacitance performance.In this work,we prepared a cellulose nanofibers(CNFs)/carbon nanotubes(CNTs)/vinasse activated carbon(VAC)(CCV)composite material with a multi-layer hierarchical conductive structure through simple vacuum filtration and freeze-drying.In this composite material,the self-assembly of CNF provides the main skeleton structure of a multi-layer hierarchical structure.CNT provides a fast path for the rapid transfer of electrons and is beneficial for the loss of electromagnetic waves.VAC provides sufficient double layer performance.The synergistic effect of the above three endows CCV composite materials with excellent energy storage performance and electromagnetic interference(EMI)shielding performance.In addition,we endowed the CCV composite with a certain shape and performance by introducing a vitrimer polymer with a dynamic cross-linked network structure.In summary,thanks to the synergistic effect of various components in the multi-layer hierarchical structure,CCV composite materials exhibit excellent integration performance,especially stable energy storage performance and EMI shielding performance.These significant properties make CCV composite materials have great application prospects in the fields of energy storage and intelligent EMI shielding.

Starting materials, processes and characteristics of bio-based foams: A review

Biofoam products have attracted considerable attention lately because there is a growing demand for green/sustainable products.To this end,various biobased foams have either been developed or are currently in development,e.g.,bio-based polyurethanes(PUs),polylactic acid(PLA),starch,and polyhydroxyalkanotates(PHAs).Indeed,significant progress has been made;however,chal-lenges still persist,for example,biobased foam products have poor processability,inferior com-patibility,thermal and strength properties.In this review,we focus on five biofoam products:namely bio-based PUs,PLA,starch,PHAs,and cellulose biofoam products,along with their prop-erties and performance,as well as their manufacturing processes.Further efforts are still needed to unlock the full potential of these bio-based products and meet the goal of complementing and gradually replacing some of their fossil-based counterparts.Finally,the challenges,as well as arising opportunities of future research directions are discussed.

Molded fiber and pulp products as green and sustainable alternatives to plastics:A mini review

There are significant incentives/pressures on decreasing the use of plastics and their related prod-ucts in the packaging industry,correspondingly,strong demands are emerging for clean,renew-able,recyclable/biodegradable packaging products.In this context,molded fiber/pulp products have attracted increasing attention,due to their green/sustainable advantages,simply because the raw materials used are plant-based and/or recycled fibers.Many companies have switched their packing practices from plastics to more environmentally friendly products,such as molded fiber products,which already have had and will continue to have obvious effect on packaging industries.This paper initially provides an overview on the general concept of molded pulp prod-ucts,and further summarizes the different types of molded fiber products in terms of natural fiber sources,manufacturing processes,current and emerging applications as well as the environmental sustainability of molded products.

Identification and characterization of slime-producing microorganisms in papermaking water loops using emulsion polymerase chain reaction techniques

Slime formation on paper machines is a critical issue that can substantially impact the quantity and quality of paper production.This problem is caused by the growth of an abundant and diverse amount of bacteria.Through the application of emulsion polymerase chain reaction(emPCR),the bacterial diversity was analyzed on paper machines and more operational taxonomic units(OTUs)were obtained.Eleven types of bacterial phyla were found that have been previously identified,including Proteobacteria(α-,β-,γ-,ε-,andφ-),Bacteroidetes,Firmicutes,Cyanobacteria,Verrucomicrobia,Actinobacteria,Spirochaetes,Chloroflexi,Deinococcus-Thermus,and Armatimonadetes.Furthermore,for the first time,there were representatives of the phyla Lentisphaerae found on paper machines.This study revealed the wide bacterial diversities of slime found on paper machines in China,which was also similar to other industrial processes.

Towards greener and more sustainable cellulose-based hand sanitizer products

More than 85%of the currently marketed hand sanitizer products are alcohol-based products,and the alcohol content is usually about 70%in order to be effective.The high alcohol content can cause dehydration,which is undesirable for sensitive skin,particularly for children.This creates opportunities for the development of innovative hand sanitizer products that are free of alcohol and have green nano-cellulose-based materials as carriers for the antibacterial agents.Good skin affinity and biocompatibility are the special features of the newly developed products,which would satisfy the need of the general public for green products.

Recent progress in the development of smart supercapacitors

Recently,with the continuous development of human society and the continuous innovation of technologies,the intelligence era has arrived.Various intelligent electronic devices continue to be developed,in which flexible wearable electronic devices are highly favored by people.To meet the requirements of the normal operation of intelligent devices,the key point lies in the development of new smart energy storage devices.Accordingly,smart supercapacitors have been widely focused on and studied by researchers recently with the introduction of intelligent functions,such as electrochromism,self‐healing,and shape memory,into supercapacitors to broaden their application fields and promote their smart development.This can meet not only people's energy needs but also people's diverse personality needs and make our life more convenient,fast,and more intelligent than ever.Therefore,it is very important to summarize related work on smart supercapacitors.Although researchers have performed much research on smart supercapacitors,there is still little literature summary on the related work of different smart supercapacitors.Accordingly,this paper mainly introduces the research progress on electrochromic,self‐healing,shape memory,and self‐charging smart supercapacitors in recent years and discusses the development prospects and challenges of smart supercapacitors.

Kinetics process for structure-engineered integrated gradient porous paper-based supercapacitors with boosted electrochemical performance

Due to their rich and adjustable porous network structure,paper-based functional materials have become a research hotspot in the field of energy storage.However,reasonably designing and making full use of the rich pore structure of paper-based materials to improve the electrochemical performance of paper-based energy storage devices still faces many challenges.Herein,we propose a structure engineering technique to develop a conductive integrated gradient porous paper-based(CIGPP)supercapacitor,and the kinetics process for the influence of gradient holes on the electrochemical performance of the CIGPP is investigated through experimental tests and COMSOL simulations.All results indicate that the gradient holes endow the CIGPP with an enhanced electrochemical performance.Specifically,the CIGPP shows a significant improvement in the specific capacitance,displays rich frequency response characteristics for electrolyte ions,and exhibits a good rate performance.Also,the CIGPP supercapacitor exhibits a low self-discharge and maintains a stable electrochemical performance in different electrolyte environments because of gradient holes.More importantly,when the CIGPP is used as a substrate to fabricate a CIGPP-PANI hybrid,it still maintains good electrochemical properties.In addition,the CIGPP supercapacitor also shows excellent stability and sensitivity for monitoring human motion and deaf-mute voicing,showing potential application prospects.This study provides a reference and feasible way for the design of structure-engineered integrated paper-based energy storage devices with outstanding comprehensive electrochemical performance.

Dialdehyde cellulose nanocrystal cross-linked chitosan foam with high adsorption capacity for removal of acid red 134

The discharge of large amounts of dye-containing wastewater seriously threats the environment.Adsorbents have been adopted to remove these dyes present in the wastewater.However,the high adsorption capacity,predominant pH-responsibility,and excellent recyclability are three challenges to the development of efficient adsorbents.The poly(acryloxyethyl trimethylammonium chloride)-graft-dialdehyde cellulose nanocrystals were synthesized in our work.Subsequently,the cationic dialdehyde cellulose nanocrystal cross-linked chitosan nanocomposite foam was fabricated via freeze-drying of the hydrogel.Under the optimal ratio of the cationic dialdehyde cellulose nanocrystal/chitosan(w/w)of 12/100,the resultant foam(Foam-12)possesses excellent absorption properties,such as high porosity,high content of active sites,strong acid resistance,and high amorphous region.Then,Foam-12 was applied as an eco-friendly adsorbent to remove acid red 134(a representative of anionic dyes)from aqueous solutions.The maximum dye adsorption capacity of 1238.1 mg∙g^(‒1) is achieved under the conditions of 20 mg∙L‒1 adsorbents,100 mg∙L^(‒1) dye,pH 3.5,24 h,and 25℃.The dominant adsorption mechanism for the anionic dye adsorption is electrostatic attraction,and Foam-12 can effectively adsorb acid red 134 at pH 2.5–5.5 and be desorbed at pH 8.Its easy recovery and good reusability are verified by the repeated acid adsorption–alkaline desorption experiments.

Design of B/N Co-doped micro/meso porous carbon electrodes from CNF/BNNS/ZIF-8 nanocomposites for advanced supercapacitors

Boron(B)and nitrogen(N)co-doped 3D hierarchical micro/meso porous carbon(BNPC)were successfully fabricated from cellulose nanofiber(CNF)/boron nitride nanosheets(BNNS)/zinc-methylimidazolate framework-8(ZIF-8)nanocomposites prepared by 2D BNNS,ZIF-8 nanoparticles,and wheat straw based CNFs.Herein,CNF/ZIF-8 acts as versatile skeleton and imparts partial N dopant into porous carbon structure,while the introduced BNNS can help strengthen the hierarchical porous superstructure and endow abundant B/N co-dopants within BNPC matrix.The obtained BNPC electrode possesses a high specific surface area of 505.4 m2/g,high B/N co-doping content,and desirable hydrophilicity.Supercapacitors assembled with BNPC-2(B/N co-doped porous carbon with a CNF/BNNS mass ratio of 1꞉2)electrodes exhibited exceptional electrochemical performance,demonstrating high capacitance stability even after 5000 charge-discharge cycles.The devices exhibited outstanding energy density and power density,as well as the highest specific capacitance of 433.4 F/g at 1.0 A/g,when compared with other similar reports.This study proposes a facile and sustainable strategy for efficiently fabrication of rich B/N co-doped hierarchical micro/meso porous carbon electrodes from agricultural waste biomass for advanced supercapacitor performance.

纤维素离子凝胶的制备及性能

开发高性能的导电凝胶已经成为推动柔性电子设备进一步发展的基石。以天然纤维素为凝胶骨架,以离子液体为导电介质,通过加热溶解-冷却凝胶化过程可以制备高性能的绿色离子液体-纤维素复合凝胶(CGel)。复合凝胶中的纤维素基体呈现三维网络结构,并包含大量的孔洞,可以有效吸附和储存离子液体,实现离子液体在纤维素基体中的均匀分布。纤维素离子复合凝胶具有较高的模量(G′>G″)、优异的透明度(88%)、良好的电学性能(2.2 mS/cm)及柔韧性。进一步通过高温加热-冷却凝胶化过程能够实现纤维素离子凝胶体系的再循环生产过程。纤维素离子凝胶展现了对水分子的高度敏感性,其电导率正比于工作湿度,有望应用于环境湿度及人体皮肤状况的高效监督检测。

Flexible N-Doped reduced graphene oxide/carbon Nanotube-MnO_(2) film as a Multifunctional Material for High-Performance supercapacitors, catalysts and sensors

A flexible 3D N-doped reduced graphene oxide(N-RGO)/carbon nanotube(CNT)eMnO_(2) hybrid film was constructed with outstanding supercapacitor,excellent oxygen reduction reaction(ORR)and good sensing performances.The resultant hybrid film possessed large specific capacitances of 418 F g^(-1) and 209 mF cm^(-2) in aqueous and solid electrolytes,and outstanding capacitance retentions of 95% and 94% were obtained for both electrolytes after experiencing 5000 cycles.A simple supercapacitor based on the resultant flexible hybrid film was further fabricated with a much smaller time constant τ0(0.38 s)than that of typical activated-carbon supercapacitors,suggesting a quick response frequency.Moreover,the assembled supercapacitor device showed high energy densities of 45.72 and 92.13 Wh kg^(-1) and simultaneously sustained large power densities of 12,526 and 15873 W kg^(-1) under a scan rate of 50 mV s^(-1) in aqueous and solid electrolytes,respectively.Furthermore,the resultant flexible film showed excellent performance in the ORR and can also be used to assemble a strain sensor with an excellent sensing performance for bending strain.

Screen printing fabricating patterned and customized full paper-based energy storage devices with excellent photothermal,self-healing,high energy density and good electromagnetic shielding performances

Supercapacitors are favored by researchers because of their high power density,especially with the acceleration of people’s life rhythm.However,their energy density,especially from the point of view of the whole energy storage device,is far lower than that of commercial batteries.In this work,a kind of customizable full paper-based supercapacitor device with excellent self-healing ability is fabricated by simple and low-cost screen printing,electropolymerization and dip coating methods.The resultant separatorfree supercapacitor device exhibits both ultrahigh gravimetric and areal specific energy(power)densities of 39 Wh kg^(-1)(69 k W kg^(-1))and 692μWh cm^(-2)(236 m W cm^(-2)),achieving excellent supercapacitor performance.Notably,the addition of vitrimers endows the whole device with outstanding self-healing properties,which is helpful for enhancing the adaptability of the device to the environment.In addition,this kind of paper-based device also displays good photothermal and electromagnetic shielding performances.These striking features make paper matrix composites attractive in the fields of supercapacitors,medical photothermal treatment and electromagnetic shielding.

Recent progress on green electromagnetic shielding materials based on macro wood and micro cellulose components from natural agricultural and forestry resources

Recent research efforts in the field of electromagnetic interference shielding(EMI)materials have focused on biomass as a green and sustainable resource.More specifically,wood and cellulose nano fiber(CNF)have many advantages,some of which include lightweight,porosity,widespread availability,low cost,and easy processing.These favorable properties have led researchers to consider these types of biomass as an EMI shielding material with great potential.At present,while many excellent published works in EMI shielding materials have investigated wood and CNF,this research area is still new,compared with non-biomass EMI shielding materials.More specifically,there is still a lack of in-depth research and summary on the preparation process,pore structure regulation,component optimization,and other factors affecting the EMI shielding of wood and CNF based EMI shielding materials.Thus,this review paper presents a comprehensive summary of recent research on wood and CNF based EMI shielding materials in recent three years in terms of the preparation methods,material structure design,component synergy,and EMI mechanism,and a forward future perspective for existing problems,challenges,and development trend.The ultimate goal is to provide a comprehensive and informative reference for the further development and exploration of biomass EMI shielding materials.