Knudsen Jan, Nilekar Anand U, Vang Ronnie T, Schnadt Joachim, Kunkes Edward L, Dumesic James A, Mavrikakis Manos, Besenbacher Flemming
Interdisciplinary Nanoscience Center (iNANO) and Department of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus C, Denmark.
J Am Chem Soc. 2007 May 23;129(20):6485-90. doi: 10.1021/ja0700855. Epub 2007 May 1.
The primary route to hydrogen production from fossil fuels involves the water-gas shift (WGS) reaction, and an improvement in the efficiency of WGS catalysts could therefore lead to a major leap forward in the realization of hydrogen economy. On the basis of a combination of high-resolution scanning tunneling microscopy, X-ray photoelectron spectroscopy, and density functional theory (DFT) calculations, we suggest the existence of a new thermodynamically stable Cu/Pt near-surface alloy (NSA). Temperature-programmed desorption and DFT reveal that this Cu/Pt NSA binds CO significantly more weakly than does Pt alone, thereby implying a considerable reduction in the potential for CO poisoning of the Cu/Pt NSA surface as compared to that of pure Pt. In addition, DFT calculations show that this Cu/Pt NSA is able to activate H2O easily, which is the rate-determining step for the WGS on several metal surfaces, and, at the same time, to bind the products of that reaction and formate intermediates rather weakly, thus avoiding possible poisoning of the catalyst surface. The Cu/Pt NSA is thus a promising candidate for an improved WGS catalyst.
从化石燃料制氢的主要途径涉及水煤气变换（WGS）反应，因此提高WGS催化剂的效率可能会在实现氢能经济方面取得重大飞跃。基于高分辨率扫描隧道显微镜、X射线光电子能谱和密度泛函理论（DFT）计算相结合的方法，我们提出存在一种新的热力学稳定的Cu/Pt近表面合金（NSA）。程序升温脱附和DFT表明，这种Cu/Pt NSA对CO的吸附比单独的Pt弱得多，这意味着与纯Pt相比，Cu/Pt NSA表面的CO中毒可能性大幅降低。此外，DFT计算表明，这种Cu/Pt NSA能够轻松激活H2O，这是几种金属表面上WGS的速率决定步骤，同时，它与该反应的产物和甲酸盐中间体的结合较弱，从而避免了催化剂表面可能的中毒。因此，Cu/Pt NSA是一种有前景的改进型WGS催化剂候选材料。
