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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >From well-defined Pt(ii) surface species to the controlled growth of silica supported Pt nanoparticles
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From well-defined Pt(ii) surface species to the controlled growth of silica supported Pt nanoparticles

机译：从定义明确的Pt（ii）表面物种到二氧化硅负载的Pt纳米颗粒的受控生长

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摘要

Silica-supported Pt nanoparticles were prepared from well-defined surface platinum(ii) surface species, obtained by grafting of well-defined Pt(ii) molecular precursors with specific ligands (Cl, Me, N(SiMe_3) _2, OSi(OtBu)_3) onto silica partially dehydroxylated at 200 and 700 °C yielding well-defined platinum(ii) surface species. This approach allowed for testing the effect of Pt density and ligands on nanoparticle size. Higher grafting densities are achieved on silica partially dehydroxylated at 200 °C due to its initially higher surface silanol density. Surface species have been synthesized from symmetrical and dissymmetrical complexes, namely (COD)Pt(Me)_2, (COD)Pt(OSi(OtBu) _3)_2, (COD)Pt(Me)(OSi(OtBu)_3), (COD)Pt(Me)(N(SiMe_3)_2), (COD)Pt(Cl)(N(SiMe _3)_2) and (COD)Pt(N(SiMe_3)_2) (OSi(OtBu)_3) yielding mono-grafted complexes of general formula (COD)Pt(R)(OSi) according to elemental analyses, diffuse reflectance infrared fourier transform (DRIFT) and carbon-13 solid-state nuclear magnetic resonance (NMR) spectroscopies. While the dimethyl-complex shows low reactivity towards grafting, bis-siloxy and dissymmetric complexes demonstrate better reactivity yielding platinum loadings up to 7.4 wt%. Upon grafting amido complexes, the surface passivation yielding Me_3SiOSi surface species is demonstrated. Nanoparticles have been synthesized from these well-defined surface species by reduction under H_2 at 300 °C, under static or flow conditions. This process yields nanoparticles with sizes ranging from 2 to 3.3 nm and narrow size dispersion from 0.5 to 1.2 nm. Interestingly, the chloride complex yields large nanoparticles from 5 to 40 nm demonstrating the strong influence of chloride over the nanoparticles growth.
机译：由明确定义的表面铂（ii）表面物种制备二氧化硅支撑的Pt纳米颗粒，该表面物种是通过将明确定义的Pt（ii）分子前体与特定配体（Cl，Me，N（SiMe_3）_2，OSi（OtBu）接枝而获得的） _3）到在200和700°C下部分脱羟基的二氧化硅上，得到明确的铂（ii）表面物质。该方法允许测试Pt密度和配体对纳米颗粒尺寸的影响。由于最初的较高表面硅烷醇密度，在200°C下部分脱羟基的二氧化硅上可获得较高的接枝密度。表面物种是由对称和不对称的配合物合成的，即（COD）Pt（Me）_2，（COD）Pt（OSi（OtBu）_3）_2，（COD）Pt（Me）（OSi（OtBu）_3），（ COD）Pt（Me）（N（SiMe_3）_2），（COD）Pt（Cl）（N（SiMe _3）_2）和（COD）Pt（N（SiMe_3）_2）（OSi（OtBu）_3）产生单元素分析，漫反射红外傅里叶变换（DRIFT）和碳13固态核磁共振（NMR）光谱分析得到的通式（COD）Pt（R）（OSi）接枝的配合物。尽管二甲基络合物对接枝的反应性低，但是双甲硅烷氧基和不对称络合物表现出更好的反应性，产生的铂负载量高达7.4 wt％。接枝酰胺配合物后，表面钝化得到了Me_3SiOSi表面物种。通过在静态或流动条件下在300°C下的H_2下还原，可以从这些定义明确的表面物种合成纳米粒子。此过程产生的纳米粒子尺寸范围为2到3.3 nm，窄尺寸分散体的范围为0.5到1.2 nm。有趣的是，氯化物络合物可产生5至40 nm的大型纳米颗粒，这表明氯化物对纳米颗粒的生长具有强大的影响。

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