Carbon supported Pt-Co alloys are among the most promising electrocatalysts towards oxygen reduction reaction(ORR)for the application in low temperature fuel cells and beyond,thus their facile and green synthesis is h...Carbon supported Pt-Co alloys are among the most promising electrocatalysts towards oxygen reduction reaction(ORR)for the application in low temperature fuel cells and beyond,thus their facile and green synthesis is highly demanded.Herein we initially report an alternate aqueous phase one-pot synthesis of such catalysts(containing nominally ca.20 wt.%Pt)based on dimethylamine borane(DMAB)reduction.The as-obtained electrocatalyst(denoted as Pt3Co/C-DMAB)is compared with the ones obtained by NaBH4 and N2H4·H2O reduction(denoted as Pt3Co/C-NaBH4 and Pt3Co/C-N2H4·H2O,respectively)as well as a commercial Pt/C,in terms of the structure and electrocatalytic property.It turns out that Pt3Co/C-DMAB exhibits the highest ORR performance among all the tested samples in an O2-saturated 0.1 mol/L HClO4,with the mass activity(specific activity)ca.4(6)times as large as that for Pt/C.After 10000 cycles of the accelerated degradation test,the half-wave potential for ORR on Pt3Co/C-DMAB decreases only by 4 mV,in contrast to 24 mV for that on Pt/C.Pt3Co/C-NaBH4 or Pt3Co/C-N2H4·H2O shows a specific activity comparable to that for Pt3Co/C-DMAB,but a mass activity similar to that for Pt/C.ICP-AES,TEM,XRD and XPS characterizations indicate that Pt3Co nanoparticles are well-dispersed and alloyed with a mean particle size of ca.3.4±0.4 nm,contributing to the prominent electrocatalytic performance of Pt3Co/C-DMAB.This simple aqueous synthetic route may provide an alternate opportunity for developing efficient practical electrocatalysts for ORR.展开更多
通过二甲基胺硼烷(dimethylamine borane,DMAB)与低分子量聚碳硅烷(low-molecular mass polycarbosilane,LPCS)反应合成硼溶胶,将硼溶胶与高分子量聚碳硅烷(high-molecular mass polycarbosilane,HPCS)共混制备含硼聚碳硅烷先驱体,经熔...通过二甲基胺硼烷(dimethylamine borane,DMAB)与低分子量聚碳硅烷(low-molecular mass polycarbosilane,LPCS)反应合成硼溶胶,将硼溶胶与高分子量聚碳硅烷(high-molecular mass polycarbosilane,HPCS)共混制备含硼聚碳硅烷先驱体,经熔融纺丝、氧化交联、热解以及1 800℃烧结制备含硼碳化硅纤维(SiC-B),研究了硼溶胶的形成过程以及SiC-B纤维的组成与性能,结果表明:由于Si—H键和B—H键的相互作用,LPCS与DMAB发生反应,实现LPCS的化学交联,从而形成高分散、高稳定的硼溶胶;硼的引入有效抑制了高温烧结过程中SiC晶粒长大,显著提高了纤维的致密度和力学性能;经1 800℃烧结后,SiC-B纤维表面光滑、断面致密,纤维平均拉伸强度为0.8 GPa。X射线衍射结果显示:SiC-B纤维的主要晶相为β-SiC和少量α-SiC,β-SiC的平均晶粒尺寸约为17.8 nm。展开更多
基金supported by the National Basic Research Program of China(973 Program,2015CB932303)the National Natural Science Foundation of China(NSFC)(21733004 and 21473039)the International Cooperation Program of Shanghai Science and Technology Committee(STCSM)(17520711200)~~
文摘Carbon supported Pt-Co alloys are among the most promising electrocatalysts towards oxygen reduction reaction(ORR)for the application in low temperature fuel cells and beyond,thus their facile and green synthesis is highly demanded.Herein we initially report an alternate aqueous phase one-pot synthesis of such catalysts(containing nominally ca.20 wt.%Pt)based on dimethylamine borane(DMAB)reduction.The as-obtained electrocatalyst(denoted as Pt3Co/C-DMAB)is compared with the ones obtained by NaBH4 and N2H4·H2O reduction(denoted as Pt3Co/C-NaBH4 and Pt3Co/C-N2H4·H2O,respectively)as well as a commercial Pt/C,in terms of the structure and electrocatalytic property.It turns out that Pt3Co/C-DMAB exhibits the highest ORR performance among all the tested samples in an O2-saturated 0.1 mol/L HClO4,with the mass activity(specific activity)ca.4(6)times as large as that for Pt/C.After 10000 cycles of the accelerated degradation test,the half-wave potential for ORR on Pt3Co/C-DMAB decreases only by 4 mV,in contrast to 24 mV for that on Pt/C.Pt3Co/C-NaBH4 or Pt3Co/C-N2H4·H2O shows a specific activity comparable to that for Pt3Co/C-DMAB,but a mass activity similar to that for Pt/C.ICP-AES,TEM,XRD and XPS characterizations indicate that Pt3Co nanoparticles are well-dispersed and alloyed with a mean particle size of ca.3.4±0.4 nm,contributing to the prominent electrocatalytic performance of Pt3Co/C-DMAB.This simple aqueous synthetic route may provide an alternate opportunity for developing efficient practical electrocatalysts for ORR.
文摘通过二甲基胺硼烷(dimethylamine borane,DMAB)与低分子量聚碳硅烷(low-molecular mass polycarbosilane,LPCS)反应合成硼溶胶,将硼溶胶与高分子量聚碳硅烷(high-molecular mass polycarbosilane,HPCS)共混制备含硼聚碳硅烷先驱体,经熔融纺丝、氧化交联、热解以及1 800℃烧结制备含硼碳化硅纤维(SiC-B),研究了硼溶胶的形成过程以及SiC-B纤维的组成与性能,结果表明:由于Si—H键和B—H键的相互作用,LPCS与DMAB发生反应,实现LPCS的化学交联,从而形成高分散、高稳定的硼溶胶;硼的引入有效抑制了高温烧结过程中SiC晶粒长大,显著提高了纤维的致密度和力学性能;经1 800℃烧结后,SiC-B纤维表面光滑、断面致密,纤维平均拉伸强度为0.8 GPa。X射线衍射结果显示:SiC-B纤维的主要晶相为β-SiC和少量α-SiC,β-SiC的平均晶粒尺寸约为17.8 nm。
