The nanoscience revolution: Merging of colloid science, catalysis and nanoelectronics
The nanoscience revolution: Merging of colloid science, catalysis and nanoelectronics
复制标题
DOI：
10.1007/s11244-007-9028-1
复制
发表时间：
2008-03-01
影响因子：
3.6
通讯作者：
Park, Jeong Young
中科院分区：
文献类型：
--
作者：
Somorjai, Gabor A.;Tao, Feng;Park, Jeong Young
将纳米科学纳入催化研究已成为理解工业催化剂反应机理和设计具有高选择性的新一代催化剂的最有力途径。纳米粒子催化剂通过受控的胶体化学路线合成。纳米结构的催化剂，如纳米点和纳米线与纳米光刻技术制造。催化剂的选择性是由几个复杂的因素，包括活性催化剂相和氧化物载体之间的界面，颗粒大小和表面结构，并选择性封闭的表面位点等，将纳米科学的优势，催化选择性的研究是分离这些复杂的因素，并在不同的催化剂体系逐一研究的能力。利用荫罩沉积技术制备了催化纳米二极管，通过对其中连续热电子流的探测，研究了氧化物-金属界面在催化反应中的作用。我们发现Pt/TiO 2纳米二极管中超热电子的产生机制与CO氧化时的转换速率密切相关。相关性表明，通过精确控制氧化物-金属界面处的热电子流来促进催化选择性的可能性。1.7-7.2 nm单分散Pt纳米粒子的催化活性表现出粒径依赖性，表明通过控制催化剂的尺寸可以提高催化选择性。在Pt（I11）单晶表面生长的不同Au覆盖度的Pt-Au合金对正己烷的4种转化通道具有不同的催化选择性，表明选择性封闭催化位是调节催化选择性的一种途径。此外，过量氢的存在和不存在导致正己烷在Pt（111）单晶表面上异构化和脱氢环化的不同催化选择性，表明通过共吸附氢的存在对活性中间体进行改性是形成催化选择性的一种方法。几个挑战，如成像吸附的分子在催化反应期间的流动性，通过高压STM和从金属纳米颗粒去除聚合物封端剂仍然存在。
The incorporation of nanosciences into catalysis studies has become the most powerful approach to understanding reaction mechanisms of industrial catalysts and designing new-generation catalysts with high selectivity. Nanoparticle catalysts were synthesized via controlled colloid chemistry routes. Nanostructured catalysts such as nanodots and nanowires were fabricated with nanolithography techniques. Catalytic selectivity is dominated by several complex factors including the interface between active catalyst phase and oxide support, particle size and surface structure, and selective blocking of surface sites, etc. The advantage of incorporating nanosciences into the studies of catalytic selectivity is the capability of separating these complex factors and studying them one by one in different catalyst systems. The role of oxide-metal interfaces in catalytic reactions was investigated by detection of continuous hot electron flow in catalytic nanodiodes fabricated with shadow mask deposition technique. We found that the generation mechanism of hot electrons detected in Pt/TiO2 nanodiode is closely correlated with the turnover rate under CO oxidation. The correlation suggests the possibility of promoting catalytic selectivity by precisely controlling hot electron flow at the oxide-metal interface. Catalytic activity of 1.7-7.2 nm monodispersed Pt nanoparticles exhibits particle size dependence, demonstrating the enhancement of catalytic selectivity via controlling the size of catalyst. Pt-Au alloys with different An coverage grown on Pt(I 11) single crystal surface have different catalytic selectivity for four conversion channels of n-hexane, showing that selective blocking of catalytic sites is an approach to tuning catalytic selectivity. In addition, presence and absence of excess hydrogen lead to different catalytic selectivity for isomerization and dehydrocyclization of n-hexane on Pt(111) single crystal surface, suggesting that modification of reactive intermediates by the presence of coadsorbed hydrogen is one approach to shaping catalytic selectivity. Several challenges such as imaging the mobility of adsorbed molecules during catalytic reactions by high pressure STM and removing polymeric capping agents from metal nanoparticles remain.