Unlocking the Catalytic Potential of TiO2-Supported Pt Single Atoms for the Reverse Water-Gas Shift Reaction by Altering Their Chemical Environment

Autor(es)

Chen, Linxiao ^[1] ; Unocic, Raymond R. ^[2] ; Hoffman, Adam S. ^[3] ; Hong, Jiyun ^[3] ; Braga, Adriano H. ^[4] ; Bao, Zhenghong ^[5] ; Bare, Simon R. ^[3] ; Szanyi, Janos ^[1]

Afiliação do(s) autor(es)

^[1] Pacific Northwest Natl Lab, Inst Integrated Catalysis, Richland, WA 99352 - USA

^[2] Oak Ridge Natl Lab, Ctr Nanophase Mat Sci, Oak Ridge, TN 37831 - USA

^[3] SLAC Natl Accelerator Lab, Stanford Synchrotron Radiat Lightsource, Menlo Pk, CA 94025 - USA

^[4] Univ Sao Paulo, Inst Chem, BR-05508000 Sao Paulo, SP - Brazil

^[5] Oak Ridge Natl Lab, Chem Sci Div, Oak Ridge, TN 37831 - USA

• Tipo de documento: Artigo Científico
• Fonte: JACS AU; v. 1, n. 7, p. 977-986, JUL 26 2021.
• Citações Web of Science: 0

Resumo

Single-atom catalysts (SACs) often exhibit dynamic responses to the reaction and pretreatment environment that affect their activity. The lack of understanding of these behaviors hinders the development of effective, stable SACs, and makes their investigations rather difficult. Here we report a reduction-oxidation cycle that induces nearly 5-fold activity enhancement on Pt/TiO2 SACs for the reverse water-gas shift (rWGS) reaction. We combine microscopy (STEM) and spectroscopy (XAS and IR) studies with kinetic measurements, to convincingly show that the low activity on the fresh SAC is a result of limited accessibility of Pt single atoms (Pt-1) due to high Pt-O coordination. The reduction step mobilizes Pt-1, forming small, amorphous, and unstable Pt aggregates. The reoxidation step redisperses Pt into Pt-1, but in a new, less O-coordinated chemical environment that makes the single metal atoms more accessible and, consequently, more active. After the cycle, the SAC exhibits superior rWGS activity to nonatomically dispersed Pt/TiO2. During the rWGS, the activated Pt-1 experience slow deactivation, but can be reactivated by mild oxidation. This work demonstrates a clear picture of how the structural evolution of Pt/TiO2 SACs leads to ultimate catalytic efficiency, offering desired understanding on the rarely explored dynamic chemical environment of supported single metal atoms and its catalytic consequences. (AU)

• Processo FAPESP: 14/50279-4 - Brasil Research Centre for Gas Innovation
• Beneficiário: Julio Romano Meneghini
• Modalidade de apoio: Auxílio à Pesquisa - Programa Centros de Pesquisa em Engenharia