Computing the Electronic Structure of Noble Metal Clusters on CdS Surfaces With Extraordinary Photocatalytic Activity
Eric Isaacs, Columbia University
CdS surfaces decorated with sub-nanometer noble metal (Au, Pt) clusters dramatically increase the rate of hydrogen production in photocatalytic water splitting[1-3]. To understand the origin of the enhanced photocatalytic activity, we employ first-principles density functional theory calculations on high-performance computing resources to investigate the semiconductor/metal cluster interface. We perform a systematic study of two-dimensional bilayer and three-dimensional structures of unsupported Au and Pt clusters with 0.7-1.5 nm diameter and obtain trends in structural, energetic, and electronic properties. We investigate the impact of surface relaxation and reconstruction on the surface energy and electronic structure of low-energy CdS surfaces, including nonpolar (10-10) and (11-20) and polar S-terminated (000-1) and Cd-terminated (0001). We explore the adsorption geometry and electronic structure of Au and Pt clusters on selected CdS surfaces, which reveals strong cluster-substrate bonding leading to significant deformation of the clusters and modification of substrate electronic structure. By elucidating the charge transfer and energy level alignment at the semiconductor/metal cluster interface, we gain insight into the enhanced photocatalytic behavior of such systems. [1]P. Shen, S. Zhao, D. Su, Y. Li and A. Orlov, Appl. Catal. B 126, 153 (2012). [2]P. Shen, S. Zhao, Q. Wu, S. Xiong, Y. Li, D. Su, A. Orlov, in preparation. [3]S. Xiong, E.B. Isaacs, Y. Li, in preparation.
Abstract Author(s): Eric B. Isaacs, Shangmin Xiong, Yan Li