A facile sulfur-assisted method to synthesize porous alveolate Fe/g-C3N4 catalysts with ultra-small cluster and atomically dispersed Fe sites  

一种简易的硫辅助方法制备多孔蜂窝状的铁超小原子簇和单原子Fe/g-C3N4

作　　者：Sufeng An Guanghui Zhang Jiaqiang Liu Keyan Li Gang Wan Yan Liang Donghui Ji Jeffrey T.Miller Chunshan Song Wei Liu Zhongmin Liu Xinwen Guo 安素峰;张光辉;刘佳强;李克艳;宛刚;梁言;纪东辉;Jeffrey T.Miller;宋春山;刘伟;刘中民;郭新闻(大连理工大学化工学院宾州-大连联合能源研究中心,精细化工国家重点实验室,中国辽宁大连116024;斯坦福大学斯坦福同步辐射光源,美国门洛帕克940253;普渡大学戴维森化学工程学院,美国印第安纳州479074;宾州州立大学,美国宾夕法尼亚州168025;中国科学院大连化学物理研究所,中国辽宁大连116023)

机构地区：[1]State Key Laboratory of Fine Chemicals,PSU-DUT Joint Center for Energy Research,School of Chemical Engineering,Dalian University of Technology,Dalian 116024,Liaoning,China [2]Stanford Synchrotron Radiation Light Source,SLAC National Accelerator Laboratory and Stanford University,Menlo Park,CA 94025,USA [3]Davidson School of Chemical Engineering,Purdue University,West Lafayette,Indiana 47907,USA [4]EMS Energy Institute,PSU-DUT Joint Center for Energy Research and Department of Energy&Mineral Engineering,The Pennsylvania State University,University Park,Pennsylvania 16802,USA [5]Dalian Institute of Chemical Physics,Chinese Academy of Sciences,Dalian 116023,Liaoning,China

出　　处：《Chinese Journal of Catalysis》2020年第8期1198-1207,共10页催化学报（英文）

基　　金：国家自然科学基金(21401017,21236008);中央高校基本科研业务费(DUT19LK17,DUT18RC(3)057);国家科学基金会合作协议(EEC-164772);美国能源部、科技办公室和基础能源科学办公室(DE-AC02-06CH11357).

摘　　要：Heterogeneous catalysts with ultra-small clusters and atomically dispersed(USCAD)active sites have gained increasing attention in recent years.However,developing USCAD catalysts with high-density metal sites anchored in porous nanomaterials is still challenging.Here,through the template-free S-assisted pyrolysis of low-cost Fe-salts with melamine(MA),porous alveolate Fe/g-C3N4 catalysts with high-density(Fe loading up to 17.7 wt%)and increased USCAD Fe sites were synthesized.The presence of a certain amount of S species in the Fe-salts/MA system plays an important role in the formation of USCAD S-Fe-salt/CN catalysts;the S species act as a"sacrificial carrier"to increase the dispersion of Fe species through Fe-S coordination and generate porous alveolate structure by escaping in the form of SO2 during pyrolysis.The S-Fe-salt/CN catalysts exhibit greatly promoted activity and reusability for degrading various organic pollutants in advanced oxidation processes compared to the corresponding Fe-salt/CN catalysts,due to the promoted accessibility of USCAD Fe sites by the porous alveolate structure.This S-assisted method exhibits good feasibility in a large variety of S species(thiourea,S powder,and NH4SCN)and Fe salts,providing a new avenue for the low-cost and large-scale synthesis of high-density USCAD metal/g-C3N4 catalysts.超小原子簇和单原子分散的活性位点(USCAD)催化剂由于其高原子利用率、高活性、高稳定性等优点,成为多相催化领域一个新兴的研究热点.USCAD通常由载体缺陷、配体和分子筛或金属有机框架的孔道和笼锚定.而制备高密度的USCAD催化剂需要载体上有足够的锚定位点.石墨相氮化碳(g-C3N4)具有高稳定性、高密度且均匀分散的氮原子,是制备USCAD催化剂的理想载体.但是传统热解法制备的金属/g-C3N4催化剂通常为块体结构,会导致金属物种被严重包覆,进而导致催化活性下降.加入固体模板可以制备得到多孔金属g-C3N4催化剂,但是后续复杂的除模板过程制约了其实际应用.因此,开发一种简易的无模板方法制备USCAD金属/g-C3N4催化剂具有重要意义.本工作开发了一种简易的硫辅助热解法制备得到蜂窝状结构的高密度(Fe载量为17.7wt%)USCADFe/g-C3N4催化剂.其多孔蜂窝状结构使催化剂能够暴露更多的USCADFe活性位点,增加了活性位点与反应物的可接近性.通过球差电镜和同步辐射X射线吸收技术证明了Fe物种的分散形式.硫辅助热解法只需要在热解铁盐/三聚氰胺前驱体中加入适量的硫源即可得到蜂窝状的USCAD Fe/g-C3N4催化剂.硫元素作为一种"牺牲载体"通过与铁离子配位促进铁物种在前驱体混合物中分散,经过高温煅烧后以SO2的形式释放而不残留在催化剂中,免除了后续的除模板过程.通过TG-MS,XPS和IR等手段证明了硫元素在热解过程中的状态变化.这种硫辅助热解法表现出非常好的普适性,改变硫源种类(硫脲、硫粉、硫氰酸铵)和铁盐种类都可以得到具有蜂窝状孔道结构的USCADFe/g-C3N4催化剂.将催化剂应用于高级氧化过程可以高效降解各种有机污染物(苯酚、亚甲基蓝、亚甲基橙、罗丹明B),催化剂性能远远优于文献报道的其它Fe基催化剂和传统热解法制备的Fe/g-C3N4催化剂.该硫辅助热解�

关 键 词：Sulfur-assisted synthesis Porous alveolate structure Ultra-small cluster and atomically dispersed active sites Fe/g-C3N4 Advanced oxidation processes 

分 类 号：O643.36[理学—物理化学]