Artiglia Luca, Rizzi Gian Andrea, Sedona Francesco, Agnoli Stefano, Granozzi Gaetano
Dipartimento di Scienze Chimiche, Unità di Ricerca CNR-INFM and INSTM, Università di Padova, Via Marzolo 1, I-35131 Padova, Italy.
J Nanosci Nanotechnol. 2008 Jul;8(7):3595-602. doi: 10.1166/jnn.2008.386.
Au/TiO(x)/Pt(111) model catalysts were prepared starting from well characterized TiO(x)/Pt(111) ultrathin films, according to an established procedure consisting in a reactive evaporation of Ti, subsequent thermal treatment in O2 or in UHV, and final deposition of submonolayer quantities of Au. Temperature Programmed Desorption measurements were performed to compare the interaction of CO in the case of two reduced TiO(x)/Pt(111) substrates (indicated as w-TiO(x) and w'-TiO(x), being the former characterized by an ordered array of defects that can act as template for the deposition of a stable array of Au nanoparticles), with the case of a stoichiometric rect'-TiO2/Pt(111) substrate. It was found that in all cases CO is molecularly adsorbed and two different desorption peaks are detected: one at approximately 140 K corresponding to CO desorption from less active adsorption sites (terraces) of the Au nanoparticles and one at approximately 200 K corresponding to CO desorption from Au nanoparticles step sites. After annealing at 770 K, the high temperature CO desorption peak is still present in the case of the defective reduced w-TiO(x) phase, supporting the good templating and stabilizing effect of such phase. On the rect'-TiO2 stoichiometric phase, the CO uptake decreases after annealing but only to a minor extent.
Au/TiO(x)/Pt(111)模型催化剂是从经过充分表征的TiO(x)/Pt(111)超薄膜开始制备的，按照既定程序进行，该程序包括钛的反应蒸发、随后在氧气中或超高真空中进行热处理，以及最后沉积亚单层量的金。进行程序升温脱附测量，以比较在两种还原的TiO(x)/Pt(111)衬底（分别标记为w-TiO(x)和w'-TiO(x)，前者具有有序的缺陷阵列，可作为稳定的金纳米颗粒阵列沉积的模板）情况下CO的相互作用，与化学计量的rect'-TiO2/Pt(111)衬底的情况。结果发现，在所有情况下，CO都是分子吸附的，并且检测到两个不同的脱附峰：一个在约140K，对应于CO从金纳米颗粒活性较低的吸附位点（平台）脱附，另一个在约200K，对应于CO从金纳米颗粒台阶位点脱附。在770K退火后，对于有缺陷的还原w-TiO(x)相，高温CO脱附峰仍然存在，这支持了该相良好的模板化和稳定化作用。在rect'-TiO2化学计量相上，退火后CO的吸附量有所下降，但幅度较小。
