Dynamic Behavior of Atomically Dispersed Catalysts: Tracking the Active Site with In-situ/Operando Spectroscopy
A thrilling ongoing interest in heterogeneous catalysis is to understand the dynamic behavior of atomically dispersed metals, which is also often referred to as single-atom catalysts (SACs). Single atom can be anchored over various supports such as metal-oxide, 2D carbon like materials, 3D materials such as zeolite, metal-organic framework and in the host matrix of other atom (known as single atom alloy). When stabilized over these materials, single atom exhibits different degree of coordination, charge on the metal and confinement within the support., These parameters strongly determine the driving force with regard to catalyst stability, performance towards catalytic reactions and most of the time governs the selectivity of the products. Hence, it strongly encourages me to understand in-depth how atoms breathe when incorporated in a host matrix under the operating conditions. Various spectroscopic tools such as X-Ray absorption spectroscopy (XAS), Fourier Transform-Infra Red (FT-IR) spectroscopy, Raman spectroscopy and few others will be used to determine the active species generated during the reactions. XAS is an emerging tool in the area of atomically dispersed catalysts, which has been used to derive information regarding coordination number, oxidation state and geometry around the metal atom upto 5-6 Å. Diffuse Reflectance Infrared Fourier Transform (DRIFT) spectroscopy will be used to identify the metal-adsorbate species generated during the reaction. A comparative study between supported atom, atom plus cluster and over cluster under operando conditions will answer the key questions raised within the proposed research.
 (a) A. Wang, J. Li, T. Zhang, Nat. Rev. Chem., 2018, 2, 65-81; (b) X.-F. Yang, A. Wang, B. Qiao, J. Li, J. Liu, T. Zhang, Acc. Chem. Res., 2013, 46, 1740-1748
 B. B. Sarma, J. Kim, J. Amsler, G. Agostini, C. Weidenthaler, N. Pfänder, R. Arenal, P. Concepción, P. Plessow, F. Studt, G. Prieto, Angew. Chem. Int. Ed., 2020, 59, 5806-5815
 B. B. Sarma, P. N. Plessow, G. Agostini, P. Concepción, N. Pfänder, L. Kang, F. R. Wang, F. Studt, G. Prieto, J. Am. Chem. Soc., 2020, 142, 14890-14902