Agar Hydrogel Template Synthesis of Mn₃O₄ Nanoparticles through an Ion Diffusion Method Controlled by Ion Exchange Membrane and Electrochemical Performance.

Qian Xue,Qiang Zhang

doi:10.3390/nano9040503

Abstract

A novel strategy, ion diffusion method controlled by ion exchange membrane combining with agar hydrogel template, was reported for the synthesis of Mn3O4 nanoparticles without any oxidizing agents. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Brunauere-Emmette-Teller (BET) isotherm were carried out to characterize the structure, morphology, pore size and distribution and specific surface area of the as-prepared nanomaterials. It is shown that the morphology and size of Mn3O4 nanoparticles can be controlled by the concentration of agar hydrogel. All the specific capacitances of the Mn3O4 samples prepared with agar hydrogel template are much higher than that of Mn3O4 prepared without any template agent. The Mn3O4 sample prepared at 1.5 g L−1 of agar hydrogel solution exhibits a highest specific capacitance of 183.0 F g−1 at the current density of 0.5 A g−1, which is increased by 293% compared with that of Mn3O4 synthesized without any template agent. The results indicate that the ion diffusion method controlled by ion exchange membrane combining with agar hydrogel template is a convenient and effective approach for preparing inorganic nanomaterials.

Highlights

As a new type of energy storage device, supercapacitors have the advantages of long cycle life, high power density, high safety and environmental friendliness [1,2,3,4], and have been applied in many fields [5]
According to their energy storage mechanism, supercapacitors can be classified as pseudocapacitors, electrical double layer capacitors (EDLCs) and hybrid supercapacitors [6]
As the electrochemical reactions of pseudocapacitors occur both on the surface and inside of electrode, the energy density and specific capacitance of pseudocapacitors are usually much higher than that of other electrochemical capacitors [7,8]

Summary

Introduction

As a new type of energy storage device, supercapacitors have the advantages of long cycle life, high power density, high safety and environmental friendliness [1,2,3,4], and have been applied in many fields [5]. The inorganic nanoparticles/hydrogel complex is obtained by the free radical polymerization and crosslinking reaction of acrylamide in the existence of crosslinking agent, and the wet gel is dried and calcined to get inorganic nanomaterials [32,33,34] This method takes the advantages of solid phase method and sol-gel method, which can mix various reactant ions uniformly at atomic level in aqueous solution, does not require the expensive alkoxides as reactants, and can control well the stoichiometric ratio of the product. The disadvantage of this method is that the synthesis process involves complex polymerization and crosslinking reaction, so it is difficult to modulate the pore size of the three-dimensional network [28]. The size of the three-dimensional network structure of the hcayndrboegceol nctarnollbeedcboynctrhoalnlegdinbgythcheacnognicnegnttrhaetioconnocfetnhteraatgioanr hoyf dthroegaegl.aIrnhoyudrrporgeevl.ioIunsowuor rpkr[e3v5i,o3u6s], wa onrokve[3l 5i,o3n6],daiffnuosivoenl imonethdoifdfucsoionntromlleetdhobdy cioonntreoxllcehdanbgye imonemexbcrhaannegewamseumsberdanfoerwsyasntuhseesdizifnogr stcmaRhasnhyatdgyaurerlndenduceOttnihioerchnn2ot-optesa·dgugdnas.tireiirHmTeoazlwtinhint2eocneiOyelntfmgtehosMasaoip.gRoaonxnlBagnbuadi3rdayttaOOeaNrlihczi24mnyhh·iinn(nndyaOeepHgandrttuHhown2grOraogooi)eongd2egprMegleanakdnlnartanithtndrtnssi3eeedct.OomcrlNcmuetT4tlophscynihan(ltecaeOatutcnaenoterHnreMoetnsihap)ydmtn2lreoanisa3erfr.nOtttettheiIahic4aonmecntoglnslneodtyipahzsoamrl.enidnafsBautoMiahertpycgpyeenaliaradccesp3irtrharaOlteroahtylieresc4ngy,m.ltegawednolInoisarnneosvdnagcycgeontagnodethmdnrhmtliohbsaeawbdetytnchesipidonrriceiaziennaenatpeclchlitcteseohuMltirynhnnwe,stnearcditwnt3tahoOihiuttoefrneiofce4nomutulercnnesot-topaaiodloaomtlnlieadfinomonbtadbemmgaiegitnnnanaateeidhigsrsttneihehiaororgopnmyinenarduydmaolorslrwwodreoonpxwivigMfetihiefedhitnuotdwlnihalsza3oooitginOobhnguradnyegky4tr toashifnguMdnsisnfici3ozcOnean4torntfolaylMlniinomnpg3pOatrrh4oteivncelmaednso.orhppaahsrotbilecoelgenys,satihgnnediefsilicezacentrotolfycMhiemnmp3Oirco4avlnepadne.rofpoarmrtiacnlecse, othf eMenle3cOtr4oncahneompiacartlicpleersfohrams baneecne

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Morphology and Structure

Electrochemical Performance of Mn3O4 Electrode