g-C3N4/NiO復(fù)合材料的制備及其對AP熱分解的影響

談玲華，徐建華，寇 波，杭祖圣，石麗麗，王 鈞

(1江蘇省先進(jìn)結(jié)構(gòu)材料與應(yīng)用技術(shù)重點(diǎn)實(shí)驗(yàn)室，南京 211167；2 南京工程學(xué)院 材料工程學(xué)院，南京 211167)

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g-C3N4/NiO復(fù)合材料的制備及其對AP熱分解的影響

談玲華1,2，徐建華2，寇 波1,2，杭祖圣1,2，石麗麗2，王 鈞2

(1江蘇省先進(jìn)結(jié)構(gòu)材料與應(yīng)用技術(shù)重點(diǎn)實(shí)驗(yàn)室，南京 211167；2 南京工程學(xué)院 材料工程學(xué)院，南京 211167)

通過混合煅燒法制備出g-C3N4/NiO復(fù)合材料，采用X射線衍射(XRD)、紅外光譜(FT-IR)、場發(fā)射掃描電子顯微鏡(FESEM)、X射線能譜(EDS)對其結(jié)構(gòu)和形貌進(jìn)行表征，利用差熱分析(DTA)和熱失重(TG)研究其對高氯酸銨(AP)熱分解的影響。結(jié)果表明：納米NiO均勻分散于g-C3N4的表面，g-C3N4/NiO使AP的高溫和低溫分解峰合并，高溫分解溫度降低62.5℃，表現(xiàn)出良好的催化作用。g-C3N4/NiO的復(fù)合催化效果優(yōu)于單獨(dú)使用g-C3N4或NiO，說明g-C3N4和NiO具有協(xié)同催化作用。

g-C3N4/NiO；高氯酸銨；催化性能；熱分解；協(xié)同作用

g-C3N4是類石墨結(jié)構(gòu)的氮化碳材料，以三嗪環(huán)(C3N3環(huán))或3-s-三嗪環(huán)(C6N7環(huán))為結(jié)構(gòu)單元，C,N原子均發(fā)生sp2雜化，通過pz軌道上的孤對電子形成一個類似于苯環(huán)結(jié)構(gòu)的大π鍵，組成高度離域的共軛體系，層與層之間存在大量自由移動的電子[1,2]。由于g-C3N4具有活性中心點(diǎn)多、化學(xué)穩(wěn)定性好、耐高溫、導(dǎo)電性能高、環(huán)境友好等特點(diǎn)[3,4]，作為新型的無金屬催化劑備受關(guān)注，在環(huán)境、能源和化工等領(lǐng)域都有較好的應(yīng)用前景[5,6]。g-C3N4不僅可作為光催化劑用于光催化分解水制氫[7]、降解有機(jī)污染物[8]等方面，還可作為多相催化劑用于CO2活化反應(yīng)[9]、Knoevenagel縮合反應(yīng)[10]等方面[11]。與g-C3N4的光催化制氫及降解等方面的大量研究相比，在多相催化方面的研究報道相對較少。

高氯酸銨(AP)是端羥基丁二烯(HTPB)復(fù)合固體推進(jìn)劑中的高能組分，在推進(jìn)劑中占60%～80%的比例，其熱分解特性與推進(jìn)劑的燃燒性能密切相關(guān)，通過研究催化劑對AP熱分解的影響可推測推進(jìn)劑的燃燒性能[21]。經(jīng)前期研究，g-C3N4對AP的熱分解表現(xiàn)出良好的催化作用，為了進(jìn)一步提高g-C3N4的催化效果，將其與對AP有良好作用效果的NiO復(fù)合[22]，探討g-C3N4/NiO復(fù)合材料對AP熱分解的催化效果，相關(guān)文獻(xiàn)鮮見報道。

本工作擬采用混合煅燒法制備出g-C3N4/NiO復(fù)合材料，利用XRD,FT-IR,FESEM和EDS等對其進(jìn)行表征，采用DTA和TG研究g-C3N4/NiO復(fù)合材料對AP熱分解的影響，并探討催化作用機(jī)理。

1 實(shí)驗(yàn)材料與方法

三聚氰胺，國藥化學(xué)試劑有限公司，分析純；無水乙醇，國藥化學(xué)試劑有限公司，分析純；納米NiO，南京艾普瑞納米科技有限公司，40nm。

采用半封閉一步熱解法[2]制備g-C3N4。取一定量的三聚氰胺放入陶瓷坩堝中(蓋上坩堝蓋)，在馬弗爐中以50℃/min升溫到500℃，焙燒1h；5min內(nèi)快速升溫到520℃，保溫焙燒1h，冷卻研磨得g-C3N4粉末。

采用混合煅燒法[19]制備g-C3N4/NiO。取0.05g納米NiO在乙醇中超聲分散10min，然后加入0.95g g-C3N4繼續(xù)超聲分散10min，完成后在研缽中研磨至物體呈糊狀，放入50℃真空烘箱中4h后，取出放入管式爐中，在300℃下焙燒1h得到g-C3N4/NiO復(fù)合材料。

將AP分別與g-C3N4，NiO，g-C3N4/NiO按照質(zhì)量比為97∶3的比例在一定量的乙醇溶液中混合、研磨，待乙醇揮發(fā)，干燥處理后得待測復(fù)合物(g-C3N4/NiO+AP)。

采用Ultima-IV型X射線衍射儀(XRD)分析樣品的晶體結(jié)構(gòu)，Kα輻射，波長為0.15406nm；采用NICOLET IS10型紅外吸收光譜分析儀(FT-IR)進(jìn)行紅外分析，掃描范圍400～4000cm-1；采用SU8010型場發(fā)射掃描電鏡(FESEM)觀察樣品形貌，操作電壓為30kV；采用GENESIS2000XMS60型X射線能譜儀(EDS)進(jìn)行樣品成分分析。

采用HTG-1型熱分析儀(TGA)進(jìn)行熱失重分析，升溫速率10℃/min，氮?dú)饬魉?0mL/min，試樣量8mg左右，氧化鋁樣品池；采用404 PC型熱分析儀(DTA)進(jìn)行差熱分析，升溫速率10℃/min，氬氣流速20mL/min，試樣量10mg左右，氧化鋁樣品池。

2 結(jié)果與分析

2.1 物相分析

對所制備的g-C3N4和g-C3N4/NiO復(fù)合材料進(jìn)行XRD分析，結(jié)果如圖1所示。

圖1 g-C3N4，NiO和g-C3N4/NiO的XRD曲線

由圖1可知，所制備的g-C3N4在2θ為13.2°和27.4°處出現(xiàn)兩個較強(qiáng)的特征衍射峰，結(jié)合JCPDS 87-1526[23]，分別對應(yīng)于g-C3N4的(100)和(002)面。其中13.2°是melon類物質(zhì)的特征峰，對應(yīng)的晶面間距為0.675nm；而27.4°是典型的層狀結(jié)構(gòu)堆積衍射峰，對應(yīng)的晶面間距為0.326nm[2]。g-C3N4/NiO復(fù)合材料既出現(xiàn)了g-C3N4的特征衍射峰，還在37.5°,43.4°,63.4°,75.6°,79.7°出現(xiàn)納米NiO的衍射峰 (JCPDS 47-1049)[24]，說明所得的材料為g-C3N4/NiO復(fù)合材料。

圖2 g-C3N4,NiO,g-C3N4/NiO的FT-IR曲線

采用場發(fā)射掃描電子顯微鏡(FESEM)進(jìn)一步觀察g-C3N4/NiO微觀形貌及結(jié)構(gòu)，結(jié)果如圖3所示。

由圖3可知，通過半封閉一步熱解法制備得到的g-C3N4樣品具有明顯的層狀結(jié)構(gòu)，比較疏松[16]。圖3(b)為g-C3N4/NiO的FESEM圖片，其中亮點(diǎn)為納米NiO，比較均勻地分散于g-C3N4的表面。對其進(jìn)行EDS分析，結(jié)果如圖3(c)所示，出現(xiàn)C，N，Ni，O的特征峰，由于g-C3N4/NiO中NiO的含量很少，所以Ni元素的特征峰比較低。FESEM和EDS結(jié)果說明NiO與g-C3N4復(fù)合，并均勻分布于g-C3N4的表面。

2.2 對AP熱分解的催化性能研究

采用DTA和TG研究g-C3N4,NiO,g-C3N4/NiO對AP熱分解的影響，結(jié)果如圖4所示。

圖3 g-C3N4(a),g-C3N4/NiO(b)的FESEM圖像及EDS曲線(c)

圖4 純AP,g-C3N4+AP和g-C3N4/NiO+AP的DTA(a),TG(b),DTG(c)曲線

由圖4可知，DTA曲線(如圖4(a)所示)有1個吸熱峰和2個放熱峰，248.3℃的吸熱峰為AP由斜方晶系轉(zhuǎn)變?yōu)榱⒎骄担?26.3℃和425.1℃分別對應(yīng)于AP的低溫分解階段高溫分解和高溫分解階段[28]。添加g-C3N4,NiO,g-C3N4/NiO對AP的晶型轉(zhuǎn)變沒有影響，但卻均能使AP的高溫分解溫度降低，對AP的熱分解有促進(jìn)作用。單獨(dú)添加g-C3N4和NiO時，高溫分解溫度分別降低30.9℃和42.0℃，而加入g-C3N4/NiO后，AP的高溫分解峰和低溫分解峰合并，在362.6℃急劇分解，分解溫度比純AP降低了62.5℃，說明g-C3N4/NiO復(fù)合材料對AP的熱分解起到較強(qiáng)的催化作用[29]。g-C3N4/NiO催化效果均比g-C3N4或NiO單獨(dú)使用時強(qiáng)，說明g-C3N4和NiO具有協(xié)同催化作用[30]。純AP的TG曲線(如圖4(b)所示)中出現(xiàn)兩個失重平臺，說明純AP的熱分解過程分兩步進(jìn)行。分別加入g-C3N4，NiO或g-C3N4/NiO后，AP的完全分解溫度均有一定降低。根據(jù)圖4(c)的DTG曲線可知，純AP在332.6℃和447.1℃出現(xiàn)失重速率極值。單獨(dú)添加g-C3N4和NiO后，失重仍然是兩個階段，第二階段失重對應(yīng)溫度降低，說明單一的g-C3N4和NiO對AP的熱分解也具有催化作用。加入g-C3N4/NiO僅出現(xiàn)一個較大的失重峰，說明在這一階段內(nèi)快速分解，分解溫度比純AP的第二分解階段降低了87.7℃，顯示出較強(qiáng)的催化效果，其效果優(yōu)于單獨(dú)使用g-C3N4或NiO，也說明g-C3N4和NiO具有協(xié)同催化作用[30]。

3 結(jié)論

(1)采用混合煅燒法制備出g-C3N4/NiO復(fù)合材料，NiO均勻分散于g-C3N4的表面。

(2)g-C3N4/NiO復(fù)合材料使AP的高低溫分解峰合并，高溫分解溫度降低了62.5℃，對AP的熱分解表現(xiàn)出良好催化作用。g-C3N4/NiO的催化效果優(yōu)于單獨(dú)使用g-C3N4或NiO，g-C3N4和NiO具有協(xié)同催化作用。

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Preparation of g-C3N4/NiO Composites and Its Effect onThermal Decomposition of Ammonium Perchlorate

TAN Ling-hua1,2,XU Jian-hua2,KOU Bo1,2,HANG Zu-sheng1,2,SHI Li-li2,WANG Jun2

(1 Jiangsu Key Laboratory of Advanced Structural Materials and Application Technology,Nanjing 211167,China；2 School of Materials Science and Engineering,Nanjing Institute of Technology,Nanjing 211167,China)

g-C3N4/NiO composites were prepared by a simple mixing-calcination method . The structure and morphology of g-C3N4/NiO were characterized by X-ray Diffraction(XRD), Fourier Transform Infrared Spectrometer(FT-IR), Field Emission Scanning Electron Microscopy(FESEM) and Energy Dispersive X-ray spectroscopy(EDS). The catalytic effect of g-C3N4/NiO on thermal decomposition of ammonium perchlorate(AP) was investigated by Differential Thermal Analysis(DTA) and Thermo Gravimetric Analysis (TG). The results show that nanometer NiO is uniformly dispersed on the surface of g-C3N4, g-C3N4/NiO composites make the two decomposition peaks of AP combine and the high-temperature decomposition peak value of AP decrease by 62.5℃, which exhibits good catalytic performance. The catalytic activity of g-C3N4/NiO is much higher than that of single-phase g-C3N4and NiO, clearly demonstrating a synergistic effect between g-C3N4and NiO.

g-C3N4/NiO;ammonium perchlorate;catalysis;thermal decomposition；synergistic effect

10.11868/j.issn.1001-4381.2016.11.016

TB321

A

1001-4381(2016)11-0096-05

江蘇省自然科學(xué)基金(BK20130747)；江蘇省高校自然科學(xué)研究課題(14KJD430002)；江蘇省先進(jìn)結(jié)構(gòu)材料與應(yīng)用技術(shù)重點(diǎn)實(shí)驗(yàn)室開放基金(ASMA201408)；南京工程學(xué)院校級科研基金項(xiàng)目(ZKJ201402)

2015-01-19；

2016-03-13

談玲華(1978-)，女，副教授，博士，從事納米材料制備及性能研究，聯(lián)系地址：南京市江寧科學(xué)園弘景大道1號南京工程學(xué)院材料工程學(xué)院(211167)，E-mail:tanlinghua@njit.edu.cn