Two major challenges,high cost and short lifespan,have been hindering the commercialization process of lowtemperature fuel cells.Professor Wei's group has been focusing on decreasing cathode Pt loadings without lo...Two major challenges,high cost and short lifespan,have been hindering the commercialization process of lowtemperature fuel cells.Professor Wei's group has been focusing on decreasing cathode Pt loadings without losses of activity and durability,and their research advances in this area over the past three decades are briefly reviewed herein.Regarding the Pt-based catalysts and the low Pt usage,they have firstly tried to clarify the degradation mechanism of Pt/C catalysts,and then demonstrated that the activity and stability could be improved by three strategies:regulating the nanostructures of the active sites,enhancing the effects of support materials,and optimizing structures of the three-phase boundary.For Pt-free catalysts,especialiy carbon-based ones,several strategies that they proposed to enhance the activity of nitrogen-/heteroatom-doped carbon catalysts are firstly presented.Then,an indepth understanding of the degradation mechanism for carbon-based catalysts is discussed,and followed by the corresponding stability enhancement strategies.Also,the carbon-based electrode at the micrometer-scale,faces the challenges such as low active-site density,thick catalytic layer,and the effect of hydrogen peroxide,which require rational structure design for the integral cathodic electrode.This review finally gives a brief conclusion and outlook about the low cost and long lifespan of cathodic oxygen reduction catalysts.展开更多
文中聚焦温敏聚合物的响应机理,通过单电子转移活性自由基聚合法(SET-LRP),以溴化亚铜/三-(2-二甲氨基乙基)胺(CuBr/Me_(6)TREN)原位歧化得到的初生零价铜(Cu^(0))及二价铜与混合配体的络合物(Cu^(Ⅱ)Br_(2)/Me_(6)TREN/PMDETA)为催化体...文中聚焦温敏聚合物的响应机理,通过单电子转移活性自由基聚合法(SET-LRP),以溴化亚铜/三-(2-二甲氨基乙基)胺(CuBr/Me_(6)TREN)原位歧化得到的初生零价铜(Cu^(0))及二价铜与混合配体的络合物(Cu^(Ⅱ)Br_(2)/Me_(6)TREN/PMDETA)为催化体系,实现了温敏单体N-异丙基丙烯酰胺(NIPAM)和甜菜碱两性离子功能单体[2-(甲基丙烯酰基氧基)乙基]二甲基-(3-磺酸丙基)氢氧化铵(DMMPPS)的原位链延伸,制备得到了系列不同嵌段比的温敏聚合物P(NIPAM-b-DMMPPS)。采用核磁共振氢谱和红外光谱对聚合物结构进行了表征。以NIPAM加料比例为40%合成的P(NIPAM-b-DMMPPS)具有最低临界溶解温度(LCST)和最高临界溶解温度(UCST),分别为41℃和25℃。考察了NaCl浓度对P(NIPAMb-DMMPPS)LCST的影响,随着NaCl浓度的增大,LCST略降低。表面张力测试结果表明,表面活性聚合物溶液浓度为1×10^(-2)g/L时,表面张力降低至45 m N/m。P(NIPAM-b-DMMPPS)在石蜡/水体系中表现出温度诱导的乳化-破乳行为,P(NIPAM-b-DMMPPS)吸附在油水界面形成乳液,提高P(NIPAM-b-DMMPPS)中PNIPAM嵌段的比例能够实现从“低温乳化、高温破乳”向“高温乳化、低温破乳”的转变,其在油水乳化破乳领域有良好的应用前景。展开更多
基金supported by the National Key Research and Development Program of China(No.2020YFB1506002,2019YFB1504503,2016YFB0101202)National 973 Program of China(No.2012CB215501)National Natural Science Foundation of China(No.52021004,22022502(2021),21822803(2019),21576031(2016),51272297(2013),20936008(2010),20676156(2007),20376088(2004),20176066(2002),29976047(2000)).
文摘Two major challenges,high cost and short lifespan,have been hindering the commercialization process of lowtemperature fuel cells.Professor Wei's group has been focusing on decreasing cathode Pt loadings without losses of activity and durability,and their research advances in this area over the past three decades are briefly reviewed herein.Regarding the Pt-based catalysts and the low Pt usage,they have firstly tried to clarify the degradation mechanism of Pt/C catalysts,and then demonstrated that the activity and stability could be improved by three strategies:regulating the nanostructures of the active sites,enhancing the effects of support materials,and optimizing structures of the three-phase boundary.For Pt-free catalysts,especialiy carbon-based ones,several strategies that they proposed to enhance the activity of nitrogen-/heteroatom-doped carbon catalysts are firstly presented.Then,an indepth understanding of the degradation mechanism for carbon-based catalysts is discussed,and followed by the corresponding stability enhancement strategies.Also,the carbon-based electrode at the micrometer-scale,faces the challenges such as low active-site density,thick catalytic layer,and the effect of hydrogen peroxide,which require rational structure design for the integral cathodic electrode.This review finally gives a brief conclusion and outlook about the low cost and long lifespan of cathodic oxygen reduction catalysts.
文摘文中聚焦温敏聚合物的响应机理,通过单电子转移活性自由基聚合法(SET-LRP),以溴化亚铜/三-(2-二甲氨基乙基)胺(CuBr/Me_(6)TREN)原位歧化得到的初生零价铜(Cu^(0))及二价铜与混合配体的络合物(Cu^(Ⅱ)Br_(2)/Me_(6)TREN/PMDETA)为催化体系,实现了温敏单体N-异丙基丙烯酰胺(NIPAM)和甜菜碱两性离子功能单体[2-(甲基丙烯酰基氧基)乙基]二甲基-(3-磺酸丙基)氢氧化铵(DMMPPS)的原位链延伸,制备得到了系列不同嵌段比的温敏聚合物P(NIPAM-b-DMMPPS)。采用核磁共振氢谱和红外光谱对聚合物结构进行了表征。以NIPAM加料比例为40%合成的P(NIPAM-b-DMMPPS)具有最低临界溶解温度(LCST)和最高临界溶解温度(UCST),分别为41℃和25℃。考察了NaCl浓度对P(NIPAMb-DMMPPS)LCST的影响,随着NaCl浓度的增大,LCST略降低。表面张力测试结果表明,表面活性聚合物溶液浓度为1×10^(-2)g/L时,表面张力降低至45 m N/m。P(NIPAM-b-DMMPPS)在石蜡/水体系中表现出温度诱导的乳化-破乳行为,P(NIPAM-b-DMMPPS)吸附在油水界面形成乳液,提高P(NIPAM-b-DMMPPS)中PNIPAM嵌段的比例能够实现从“低温乳化、高温破乳”向“高温乳化、低温破乳”的转变,其在油水乳化破乳领域有良好的应用前景。
基金financially supported by the National Key Research and Development Program of China (2020YFB1506001)the National Natural Science Foundation of China (Grant Nos. 51772037, 52021004, 22022502, 21761162015, 22179012, 22208034)+1 种基金the Program for the Top Young Innovative Talents of Chongqing (02200011130003)the graduate scientific research and innovation foundation of Chongqing (CYB20044)。
