N,P共掺杂香蒲基炭气凝胶的制备、表征及其电化学性能

Preparation,Characterization and Electrochemical Performance of N,P Co-doped Cattail-derived Carbon Aerogels

以香蒲花序为原料,NH_(4)H_(2)PO_(4)为掺杂剂,经酸性NaClO_(2)预处理、超声波细胞破碎处理、冷冻干燥、高温炭化制备N、P共掺杂香蒲基炭气凝胶(NPCA)。采用SEM、N_(2)吸附/脱附、XRD、XPS对NPCA的形貌、孔隙结构、晶相结构、表面化学组成进行表征,系统研究了掺杂量和炭化温度对NPCA电化学性能的影响。研究结果表明:NPCA是由无定形炭组成的三维网状立体结构;NPCA表面氮元素以吡啶氮(N-6)、吡咯氮(N-5)、石墨化氮(N-Q)和氧化氮(N-X)的形式存在,磷元素以P—O和P—C的形式存在。NH_(4)H_(2)PO_(4)的掺杂量和炭化温度影响NPCA的孔隙结构及表面化学结构。NPAC的较佳制备条件为:香蒲纤维素与NH_(4)H_(2)PO_(4)的质量比为1∶2,炭化温度800℃。此条件下制备的NPAC-2-800具有丰富的孔隙结构和表面官能团,比表面积为599.88 m^(2)/g,总孔容积为0.27 cm^(3)/g,微孔容积为0.20 cm^(3)/g,平均孔径为3.69 nm,并且NPCA的N、P质量分数分别为5.69%和5.12%。电化学性能测试结果表明:在6 mol/L KOH溶液、三电极体系中,在1 A/g的电流密度下NPCA-2-800的比电容为249 F/g,比未掺杂NH_(4)H_(2)PO_(4)样品的比电容(106.7 F/g)增加了133.4%,并且具有较好的倍率性能。

N and P co-doped carbon aerogels(NPCA)were prepared from cattail inflorescence with NH_(4)H_(2)PO_(4)as dopant by pretreatment with acidic sodium chlorite,ultrasonic cell fragmentation,freeze-drying and carbonization at high temperature.The surface morphology,pore structure,crystalline structure and surface chemical composition of NPCA were characterized by SEM,N_(2) adsorption/desorption,XRD and XPS.The effects of doping amounts and carbonization temperatures on the electrochemical properties of NPCA were systematically studied.The results of research showed that NPCA was a three-dimensional network structure that composed of amorphous carbon.The nitrogen element on the surface of NPCA existed in the form of pyridine nitrogen(N-6),pyrrole nitrogen(N-5),graphitization nitrogen(N-Q)and oxidation state of nitrogen(N-X),and the phosphorus element existed in the form of P-O and P-C.The pore structure and surface chemical structure of NPCA were greatly affected by doping amount of NH_(4)H_(2)PO_(4)and carbonization temperature.The optimum preparation conditions of NPAC were that the mass ratio of cattail-based cellulose to ammonium dihydrogen phosphate was 1∶2 and the carbonization temperature was 800℃.The NPAC-2-800 prepared under this condition has rich pore structure and surface functional groups.Furthermore,the specific surface area was 599.88 m^(2)/g,the total pore volume was 0.27 cm^(3)/g,the micropore volume was 0.20 cm^(3)/g,and the average pore size was 3.69 nm,the N and P contents of NPCA were 5.69%and 5.12%,respectively.The electrochemical properties of the NPCA were measured by three electrode system in 6 mol/L KOH solution.The specific capacitance of NPCA-2-800 was 249 F/g at a current density of 1 A/g,which was 133.4%higher than that of the undoped sample(106.7 F/g),and had good rate performance.