Resorcinol-formaldehyde resin-based porous carbon spheres with high CO_2 capture capacities

Porous carbon spheres are prepared by direct carbonization of potassium salt of resorcinol-formaldehyde resin spheres, and are investigated as COadsorbents. It is found that the prepared carbon materials still maintain the typical spherical shapes after the activation, and have highly developed ultra-microporosity with uniform pore size, indicating that almost the activation takes place in the interior of the polymer spheres. The narrow-distributed ultra-micropores are attributed to the "in-situ homogeneous activation"effect produced by the mono-dispersed potassium ions as a form of -OK groups in the bulk of polymer spheres. The CS-1 sample prepared under a KOH/resins weight ratio of 1 shows a very high COcapture capacity of 4.83 mmol/g and good CO/Nselectivity of7-45. We believe that the presence of a welldeveloped ultra-microporosity is responsible for excellent COsorption performance at room temperature and ambient pressure.

Nitrogen-doped hierarchically porous carbon spheres for low concentration CO_(2) capture

Synthesis of spherical carbon beads with effective CO_2 capture capability is highly desirable for large scale application of CO2 sorption, but remains challenging. Herein, a facile and efficient strategy to prepare nitrogen-doped hierarchically porous carbon spheres was developed via co-pyrolyzation of poly(vinylidene chloride) and melamine in alginate gel beads. In this approach, melamine not only serves as the nitrogen precursor, but also acts as a template for the macropores structures. The nitrogen contents in the hierarchically porous carbon spheres reach a high level, ranging from 11.8 wt% to 14.7 wt%, as the melamine amount increases. Owing to the enriched nitrogen functionalities and the special hierarchical porous structure, the carbon spheres exhibit an outstanding CO_2 capture performance, with the dynamic capacity of as much as about 7 wt% and a separation factor about 49 at 25 °C in a gas mixture of CO_2/N_2(0.5:99.5, v/v).

Hierarchical porous nitrogen,oxygen,and phosphorus ternary doped hollow biomass carbon spheres for high-speed and long-life potassium storage

Limited lithium resources have promoted the exploration of new battery technologies.Among them,potassium-ion batteries are considered as promising alternatives.At present,commercial graphite and other carbon-based materials have shown good prospects as anodes for potassium-ion batteries.However,the volume expansion and structural collapse caused by periodic K+insertion/extraction have severely restricted further development and application of potassium-ion batteries.A hollow biomass carbon ball(NOP-PB)ternarily doped with N,O,and P was synthesized and used as the negative electrode of a potassium-ion battery.X-ray photoelectron spectroscopy,Fourier‐transform infrared spectroscopy,and transmission electron microscopy confirmed that the hollow biomass carbon spheres were successfully doped with N,O,and P.Further analysis proved that N,O,and P ternary doping expands the interlayer distance of the graphite surface and introduces more defect sites.DFT calculations simultaneously proved that the K adsorption energy of the doped structure is greatly improved.The solid hollow hierarchical porous structure buffers the volume expansion of the potassium insertion process,maintains the original structure after a long cycle and promotes the transfer of potassium ions and electrons.Therefore,the NOP‐PB negative electrode shows extremely enhanced electrochemical performance,including high specific capacity,excellent long‐term stability,and good rate stability.

High-yield production of porous carbon spheres derived from enzymatic hydrolysis lignin for zinc ion hybrid capacitors

The widespread implementation of supercapacitors is hindered by the limited energy density and the pricey porous carbon electrode materials.The cost of porous carbon is a significant factor in the overall cost of supercapacitors,therefore a high carbon yield could effectively mitigate the production cost of porous carbon.This study proposes a method to produce porous carbon spheres through a spray drying technique combined with a carbonization process,utilizing renewable enzymatic hydrolysis lignin as the carbon source and KOH as the activation agent.The purpose of this study is to examine the relationship between the quantity of activation agent and the development of morphology,pore structure,and specific surface area of the obtained porous carbon materials.We demonstrate that this approach significantly enhances the carbon yield of porous carbon,achieving a yield of 22%in contrast to the conventional carbonization-activation method(9%).The samples acquired through this method were found to contain a substantial amount of mesopores,with an average pore size of 1.59 to 1.85 nm and a mesopore ratio of 25.6%.Additionally,these samples showed high specific surface areas,ranging from 1051 to 1831 m2·g^(−1).Zinc ion hybrid capacitors with lignin-derived porous carbon cathode exhibited a high capacitance of 279 F·g^(−1) at 0.1 A·g^(−1) and an energy density of 99.1 Wh·kg^(−1) when the power density was 80 kW·kg^(−1).This research presents a novel approach for producing porous carbons with high yield through the utilization of a spray drying approach.

Cobalt-nitrogen co-doped porous carbon sphere as highly efficient catalyst for liquid-phase cyclohexane oxidation with molecular oxygen and the active sites investigation

The selective oxidation of cyclohexane to cyclohexanone and cyclohexanol(KA oil)is a challenging issue in the chemical industry.At present the industrial conversion of cyclohexane to cyclohexanone and cyclohexanol is normally controlled at less than 5%selectivity.Thus,the development of highly active and stable catalysts for the aerobic oxidation of cyclohexane is necessary to overcome this low-efficiency process.Therefore,we have developed a cobalt-nitrogen co-doped porous sphere catalyst,Co-NC-x(x is the Zn/Co molar ratio,where x=0,0.5,1,2,and 4)by pyrolyzing resorcinol-formaldehyde resin microspheres.It achieved 88.28%cyclohexanone and cyclohexanol selectivity and a cyclohexane conversion of 8.88%under Co-NC-2.The results showed that the introduction of zinc effectively alleviated the aggregation of Co nanoparticles and optimized the structural properties of the material.In addition,Co0 and pyridinic-N are proposed to be the possible active species,and their proportion efficiently increased in the presence of Zn^(2+)species.In this study,we developed a novel strategy to design highly active catalysts for cyclohexane oxidation.

Ru complex and N,P-containing polymers confined within mesoporous hollow carbon spheres for hydrogenation of CO_(2)to formate

The development of reliable catalysts with both excellent activity and recyclability for carbon dioxide(CO_(2))hydrogenation is challenging.Herein,a ternary hybrid heterogeneous catalyst,involving mononuclear Ru complex,N,P-containing porous organic polymers(POPs),and mesoporous hollow carbon spheres(Ru^(3+)-POPs@MHCS)is reported for CO_(2)hydrogenation to formate.Based on comprehensive structural analyses,we demonstrated that Ru^(3+)-POPs were successfully immobilized within MHCS.The optimized Ru^(3+)-0.5POPs@MHCS catalyst,which was obtained with about 5 wt.%Ru^(3+)and 0.5 mmol POPs polymers confined into 0.3 g MHCS,exhibited high catalytic activity for CO_(2)hydrogenation to formate(turnover number(TON)>1,200 for 24 h under mild reaction conditions(4.0 MPa,120℃))and improved durability,compared to Ru^(3+)catalysts without POPs polymers(Ru^(3+)-MHCS)and unencapsulated MHCS(Ru^(3+)-0.5POPs)catalysts.The improved catalytic performance is attributed to the high surface area and large pore volume of MHCS which favors dispersion and stabilization of Ru^(3+)-POPs.Furthermore,the MHCS and POPs showed high CO_(2)adsorption ability.Ru^(3+)-POPs encapsulated into MHCS reduces the activation energy barrier for CO_(2)hydrogenation to formate.

Atomic Pt anchored on hierarchically porous monolithic carbon nanowires as high-performance catalyst for liquid hydrogenation

Monolithic catalysts play a crucial role in various catalytic applications,e.g.,chemical synthesis,energy conversion,and environmental treatment,but their catalytic efficiency is often limited by the restricted mass transfer and insufficient exposure of active sites.Herein,we present a dual-templating strategy to fabricate atomic Pt dispersed on monolithic N-doped mesoporous carbon nanowires(Pt_(1)/NMCW)with abundant super-/macropores,which,as monolithic catalyst,exhibits high catalytic performance in hydrogenation of 4-nitrophenol(4-NP).During synthesis,triblock copolymer(Pluronic F127)is employed as a primary soft template to generate the mesoporous structured carbon nanowires to improve the accessibility of Pt single sites;KCl crystallite is used as a secondary hard template to create the super-/macropores,which are beneficial for enhancing the mass transfer efficiency.Thanks to the dual-templating strategy that creates the monolithic carbon nanowires with hierarchically porous structure,the obtained Pt_(1)/NMCW shows highly enhanced catalytic activity in 4-NP hydrogenation,outperforming its analogue synthesized without using KCl as template and being comparable to the nano-powder catalyst(i.e.,atomic Pt loaded on the Ndoped carbon nanospheres,Pt_(1)/NCS).

Sculpturing solid polymer spheres into internal gridded hollow carbon spheres under controlled pyrolysis micro-environment

Porous carbon spheres with an internal gridded hollow structure and microporous shell have always been attractive as carbon hosts for electrochemical energy storage. Such carbon hosts can limit active species loss and enhance electronic conductivity throughout the entire framework. Herein, a synthesis approach of internal gridded hollow carbon spheres is developed from solid polymer spheres rather than originally gridded polymer spheres under a controlled pyrolysis micro-environment. The crucial point of this approach is the fabrication of a silica fence around solid polymer spheres, under which the free escaping of the pyrolysis gas will be partly impeded, thus offering a reconstitution opportunity for an internal structure of solid polymer spheres. As a result, the interior of carbon spheres is sculptured into a gridded hollow structure with microporous skin. Furthermore, the size and density of carbon-bridge grids can be modulated by altering the crosslinking degree of polymer spheres and varying pyrolysis conditions. Such gridded hollow carbon spheres show good performance as sulfur hosts for Li-S battery.

Synthesis of porous carbon spheres derived from lignin through a facile method for high performance supercapacitors

Porous carbon spheres（PCS） derived from lignin have been prepared through a facile method and fabricated as electrodes for electric double-layer capacitors. Spherical shaped mixtures of lignosulfonate and crystalized KOH are formed by spray drying of a solution of lignosulfonate and KOH. Activation by KOH is performed at high temperatures along with lignosulfonate carbonization. With an appropriate pore structure, the obtained PCS have a specific surface area of 1372.87 m^2 g^-1 and show a capacitance of 340 F g^-1 in 3 M KOH at a current density of 0.5 A g^-1. Moreover, a symmetric supercapacitor fabricated using the PCS as electrodes show a maximum capacitance of 68.5 F g^-1, and an energy density of 9.7 W h kg^-1 at a power density of 250 W kg^-1. The capacity retention is more than 94.5% after 5000 galvanostatic chargedischarge cycles. The excellent characteristics seem to be ascribed to the pore structures of PCS that have a large specific surface area and a low electrical resistance.

Mechanism investigation of enhanced electrochemical H_(2)O_(2) production performance on oxygen-rich hollow porous carbon spheres

Electrochemical oxygen reduction is a promising approach for the sustainable decentralized production of H_(2)O_(2),but its viable commercialization is hindered by the insufficient development of efficient electrocatalysts.Here,we demonstrate a promising carbon-based catalyst,consisting of oxygen-rich hollow mesoporous carbon spheres(HMCSs),for selective oxygen reduction to H_(2)O_(2).The as-prepared HMCS exhibits high onset potential(0.82 V)and half-wave potential(0.76 V),delivering a significant positive shift compared with its oxygen-scarce counterparts and commercial Vulcan carbon.Moreover,excellent H2O2 selectivity(above 95%)and electrochemical stability(7%attenuation after 10 h operation)make this material a state-of-the-art catalyst for electrochemical H_(2)O_(2) production.The outstanding performance arises from a combination of several aspects,such as porous structure-facilitation of mass transport,large surface area,and proper distribution of oxygen-containing functional groups modification on the surface.Furthermore,the proposed oxygen reduction reaction(ORR)mechanism on HMCS surface reveals that-OH functional groups help promote the first electron transfer process while other oxygen modification facilitate the second electron transfer.

Direct synthesis of tin spheres/nitrogen-doped porous carbon composite by self-formed template method for enhanced lithium storage

To inhibit the agglomeration of tin-based nanomaterials and simplify the complicated synthesis process,a facile and eco-friendly self-formed template method is reported to synthesize tin submicron spheres dispersed in nitrogen-doped porous carbon(Sn/NPC)by pyrolysis of a mixture of disodium stannous citrate and urea.The vital point of this strategy is the formation of Na_(2)CO_(3)templates during pyrolysis.This self-formed Na_(2)CO_(3)acts as porous templates to support the formation of NPC.The obtained NPC provides good electronic conductivity,ample defects,and more active sites.Serving as anode for Li-ion batteries,the Sn/NPC electrode obtains a stable discharge capacity of 674.1 mAh/g after 150 cycles at 0.1 A/g.Especially,a high discharge capacity of 331.2 mAh/g can be achieved after 1100 cycles at 3 A/g.Additionally,a full cell coupled with LiCoO_(2)as cathode yields a discharge capacity of 524.8 mAh/g after 150 cycles at 0.1 A/g.In-situ XRD is implemented to investigate the alloying/dealloying reaction mechanisms.Density functional theory calculation ulteriorly explicates that NPC heightens intrinsic electronic conductivity,and NPC especially pyrrolic-N and pyridinic-N doping facilitates the Li-adsorption ability.Climbing image nudged elastic band method reveals low Li~+diffusion energy barrier in presence of N atoms,which accounts for the terrific electrochemical properties of Sn/NPC electrode.

Porous carbon spheres anode with the stable output of low delithiation plateau and constant delithiation ratio for lithium ion hybrid capacitor

Porous carbon spheres derived from the facile hydrothermal treatment associated with the calcination process exhibit the good spherical morphology and unique porous structure.For the Li-based half-cell test,porous carbon spheres electrode not only exhibits larger reversible capacities and better compatibility as compared to the widely-used graphite,but also provides stable delithiation plateaus under different current density.Additionally,the delithiation ratio below 1 V almost accounts for a constant value(around 70%)with the increase of current density,evidencing that Li intercalation storage is the dominant model and Li insertion/extraction processes are propitious.The lithium ion hybrid capacitor configured with S-doped mesoporous graphene and porous carbon spheres as cathode and anode,delivers satisfied energy and power densities(up to 177 Wh kg^(−1) and 12,303 W kg^(−1),respectively)as well as long-term cyclability,which is superior to the corresponding S-doped mesoporous graphene//graphite and activated carbon//porous carbon spheres.In addition,the developed synthesis strategy is in favor of the realization of the scalable production of porous carbon spheres.

Sandwich-like chitosan porous carbon Spheres/MXene composite with high specific capacitance and rate performance for supercapacitors

The application of porous carbon microspheres derived from pure biomass in supercapacitors is restricted due to their limited reactive groups.MXene owns a combination of redox Faradic surface with good metallic conductivity and hydrophilicity,which assists to obtain high pseudocapaci-tance and energy density.Herein,Ti_(3)C_(2)T_(x)MXene was introduced to chitosan-based porous carbon microsphere(CPCM)to fabricated sandwich-like structure(CPCM/MXene)through electrostatic interaction.The Ti_(3)C_(2)T_(x)protected the spherical structure of CPCM.Meanwhile,CPCM hindered the reaggregation of Ti_(3)C_(2)T_(x)by inserting in the Ti_(3)C_(2)T_(x)layers,promoting the electrolyte migra-tion kinetics.The synergistic effect endowed CPCM/MXene high specific capacitance of 362 F/g at current density of 0.5 A/g and acceptable cycling stability with 93.87%capacitance retention at a high current density of 10 A/g after 10,000 cycles.Furthermore,CPCM/MXene displayed a high energy density of 27.8 W/(h•kg)at 500.0 W/kg of power density.These satisfactory perfor-mances prove that combining Ti_(3)C_(2)T_(x)MXene nanosheets with porous carbon microspheres is a considering method to construct a new generation electrode material of supercapacitor.

Hollow-in-hollow carbon spheres with hollow foam-like cores for lithium-sulfur batteries

Lithium-sulfur batteries have attracted increasing attention because of their high theoretical capadty. Using sulfur/carbon composites as the cathode materials has been demonstrated as an effective strategy to optimize sulfur utilization and enhance cycle stability as well. In this work hollow-in-hollow carbon spheres with hollow foam-like cores （HCSF@C） are prepared to improve both capability and cycling stability of lithium-sulfur batteries. With high surface area and large pore volumes, the loading of sulfur in HCSF@C reaches up to 70 wt.%. In the resulting S/HCSF@C composites, the outer carbon shell serves as an effective protection layer to trap the soluble polysulfide intermediates derived from the inner component. Consequently, the S/HCSF@C cathode retains a high capacity of 780 mAh/g after 300 cycles at a high charge/discharge rate of 1 A/g.

Phenylenediamine-formaldehyde chemistry derived N-doped hollow carbon spheres for high-energy-density supercapacitors

Porous carbon spheres represent an ideal family of electrode materials forsupercapacitors because of the high surface area,ideal conductivity,negligible aggregation,and ability to achieve space efficient packing.However,the development of new synthetic methods towards porous carbon spheres still remains a great challenge.Herein,N-doped hollow carbon spheres with an ultrahigh surface area of2044 m^(2)/g have been designed based on the phenylenediamine-formaldehyde chemistry.When applied in symmetric supercapacitors with ionic electrolyte(EMIBF_4),the obtained N-doped hollow carbon spheres demonstrate a high capacitance of 234 F/g,affording an ultrahigh energy density of 114.8 Wh/kg.Excellent cycling stability has also been achieved.The impressive capacitive performances make the phenylenediamine-formaldehyde resin derived N-doped carbon a promising candidate electrode material for supercapacitors.

In-situ deposition of Pd/Pd_(4)S heterostructure on hollow carbon spheres as efficient electrocatalysts for rechargeable Li-O_(2)batteries

The sluggish kinetics of oxygen reduction reaction(ORR)and oxygen evolution reaction(OER)have always restricted the development of lithium oxygen batteries(LOBs).Herein,hollow carbon spheres loaded with Pd/Pd_(4)S heterostructure(Pd/Pd_(4)S@HCS)were successfully prepared via the in-situ deposition to improve the electrocatalytic activities for both ORR and OER in LOBs.With the welldispersed Pd/Pd_(4)S nanoparticles,the hierarchical composite with large specific surface area offers favorable transport channels for ions,electron and oxygen.Especially,the Pd/Pd_(4)S nanoparticles could exhibit excellent electrochemical performance for ORR and OER due to their intrinsic catalytic property and interfacial effect from the heterostructure.Therefore,the LOBs with Pd/Pd_(4)S@HCS as cathode catalyst show improved specific capacities,good rate ability and stable cycling performance.

Integrated interconnected porous and lamellar structures realized fast ion/electron conductivity in high-performance lithium-sulfur batteries

The practical application of high-energy-density lithium-sulfur(Li-S)batteries have been highly praised for energy storage devices,while are largely hindered by the“shuttling effect”.Herein,core-shell carbon spheres composed of interlinked porous core and lamellar shell were designed to restrain the polysulfide shuttling.The microporous structure with pore size of around 1 nm effectively trap lithium polysulfides.Furthermore,the interconnected porous core shortens the ion transfer distance and the lamellar carbon shell endows the carbon spheres with fast electron conduction,finally facilitating polysulfide conversion kinetics.Therefore,the Li-S batteries with the carbon spheres as the interlayer show high discharge specific capacity of 1002 m Ah/g at 2 C with 574 m Ah/g remaining after 600 cycles,and high areal capacity of 5.48 m Ah/cm^(2) with sulfur loading of 4.67 mg/cm^(2) at 0.1 C.The corresponding pouch cells also exhibit stable cycling stability with an initial discharge specific capacity of 1082 m Ah/g at 0.1 C.

基于铂/碳球的乙酰胆碱酯酶传感器在农药乐果检测中的应用研究

基于农药乐果对乙酰胆碱酯酶的抑制作用,构建生物传感器,实现了农药乐果的快速、高灵敏检测。合成了纳米材料铂/碳球(Pt/Cs),利用其比表面积大、导电性好的优势,构建乙酰胆碱酯酶(ACh E)传感器。铂/碳球修饰电极比裸电极的阻抗更低,峰电流增加了147.06%,说明该材料能很好地保持酶的催化活性。在最优实验条件下,用ACh E传感器检测农药乐果,在1.0×10^(-9)~1.0×10^(-6)g/L范围,乐果浓度的负对数与抑制率呈良好的线性关系,其检出限为7.3×10^(-12)g/L(按抑制率为10%计算)。对纺织品样品进行加标回收实验,测得回收率为86.2%~101.7%。

直接乙醇燃料电池阳极催化剂Pt-SnO2/C的制备及性能表征

采用水热反应法来制备不同浓度及不同反应时间的碳球，以葡萄糖为反应原料，在未添加任何模板剂的条件下，制备了尺寸可控的中空碳球为催化剂载体，加入自制的SnO2为助剂，运用微波辅助乙二醇还原氯铂酸法合成催化剂。利用扫描电镜（SEM）对所制备的碳球载体进行了表征，利用电化学工作站对所制备的催化剂进行了电化学性能测试。结果表明，碳球随葡萄糖溶液浓度的增长，碳球的粒径随之增大，其中0．5mol·L^-1，4h的碳球分散性最好，且粒径尺寸较小约为0．62μm；同时碳球随反应时间的增加，粒径增大，但反应时间过长会出现焦结粘着现象，从而降低催化剂的催化氧化性能；加入助剂SnO2合成的催化剂可显著提高乙醇的催化氧化的活性，稳定性和抗中毒能力。