(Invited) Atomic Layer Deposition for Catalyst “Bottom-up” Synthesis

Abstract

Catalyst synthesis with precise control over the structure of catalytic active sites at the atomic level is of essential importance for the scientific understanding of reaction mechanisms and for rational design of advanced catalysts with high performance. Such precise control is achievable using atomic layer deposition (ALD). ALD is similar to chemical vapor deposition (CVD), except that the deposition is split into a sequence of two self-limiting surface reactions between gaseous precursor molecules and a substrate. The unique self-limiting feature of ALD allows conformal deposition of catalytic materials on a high surface area catalyst support at the atomic level. The deposited catalytic materials can be precisely constructed on the support by varying the number and type of ALD cycles. As an alternative to the wet-chemistry based conventional methods, ALD provides a cycle-by-cycle “bottom-up” approach for nanostructuring supported catalysts with near atomic precision [1, 2]. In this presentation, the capability of achieving precise control over the particle size of monometallic nanoparticles by ALD is emphasized. The possibility of the preparation of single-atom metal catalysts by ALD at elevated temperatures will be discussed [3]. For supported bimetallic catalyst synthesis, I will show the challenges of combing two metal ALD processes to form bimetallic nanoparticles synthesis. Then our recent the strategy developed for selective metal-on-metal ALD for precise synthesis of supported bimetallic catalysts while excluding monometallic formation are particularly highlighted [4, 5]. In the final part of my presentation, I will focus on oxide ALD on metals for precise synthesis of nanostructured metal catalysts, therein, I will discuss the methods of tailoring the catalytic performance of metal catalysts including activity, selectivity and stability, through selective blocking of the low-coordination sites of metal nanoparticles, the confinement effect, and the formation of new metal-oxide interfaces [6, 7]. References (1) J.L. Lu, J.W. Elam, P.C. Stair, Acc. Chem. Res. 46 (2013) 1806-1815.(2) J.L. Lu, J.W. Elam, P.C. Stair, Surf. Sci. Rep. 2016, doi:10.1016/j.surfrep.2016.1003.1003.(3) H. Yan, H. Cheng, H. Yi, Y. Lin, T. Yao, C.L. Wang, J.J. Li, S.Q. Wei, J.L. Lu, J. Am. Chem. Soc. 2015, 137, 10484-10487(4) J.L. Lu, K.B. Low, Y. Lei, J.A. Libera, A. Nicholls, P.C. Stair, J.W. Elam, Nat. Commun. 2014, 5 3264.(5) H.W. Wang, C.L. Wang, H. Yan, H. Yi, J.L. Lu, J. Catal. 2015, 324, 59-68.(6) J.L. Lu, B. Fu, M.C. Kung, G. Xiao, J.W. Elam, H.H. Kung, P.C. Stair, Science 2012, 335, 1205.(7) H. Yi, H.Y. Du, Y.L. Hu, H. Yan, H.-L. Jiang, J.L. Lu, ACS Catal. 2015, 5, 2735-2739.