Distinct Crystal-Facet-Dependent Behaviors for Single-Atom Palladium-On-Ceria Catalysts: Enhanced Stabilization and Catalytic Properties

Botao Hu; Kaian Sun; Zewen Zhuang; Zheng Chen; Shoujie Liu; Weng-Chon Cheong; Cheng Chen; Mingzhen Hu; Xing Cao; Junguo Ma; Renyong Tu; Xusheng Zheng; Hai Xiao; Xiao Chen; Yi Cui; Qing Peng; Chen Chen; Yadong Li

doi:10.1002/adma.202107721

Distinct Crystal-Facet-Dependent Behaviors for Single-Atom Palladium-On-Ceria Catalysts: Enhanced Stabilization and Catalytic Properties

Adv Mater. 2022 Apr;34(16):e2107721. doi: 10.1002/adma.202107721. Epub 2022 Mar 10.

Authors

Botao Hu^{1

2}, Kaian Sun¹, Zewen Zhuang¹, Zheng Chen³, Shoujie Liu⁴, Weng-Chon Cheong⁵, Cheng Chen⁶, Mingzhen Hu⁷, Xing Cao¹, Junguo Ma¹, Renyong Tu¹, Xusheng Zheng⁸, Hai Xiao¹, Xiao Chen⁹, Yi Cui¹⁰, Qing Peng¹, Chen Chen¹, Yadong Li¹

Affiliations

¹ Department of Chemistry, Tsinghua University, Beijing, 100084, P. R. China.
² Qian Xuesen Laboratory of Space Technology, China Academy of Space Technology, Beijing, 100094, P. R. China.
³ College of Chemistry and Materials Science, Anhui Normal University, Wuhu, 241000, P. R. China.
⁴ Chemistry and Chemical Engineering Guangdong Laboratory, Shantou, 515031, P. R. China.
⁵ Department of Physics and Chemistry, Faculty of Science and Technology, University of Macau, Macau, 999078, P. R. China.
⁶ Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, P. R. China.
⁷ School of Chemical Sciences, University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
⁸ National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029, P. R. China.
⁹ Beijing Key Laboratory of Green Chemical Reaction Engineering and Technology, Department of Chemical Engineering, Tsinghua University, Beijing, 100084, P. R. China.
¹⁰ Suzhou Institute of Nano-Tech and Nano-Bionics (SINANO), Chinese Academy of Sciences, Suzhou, 215123, P. R. China.

PMID: 35142396
DOI: 10.1002/adma.202107721

Abstract

High-performance, fully atomically dispersed single-atom catalysts (SACs) are promising candidates for next-generation industrial catalysts. However, it remains a great challenge to avoid the aggregation of isolated atoms into nanoparticles during the preparation and application of SACs. Here, the evolution of Pd species is investigated on different crystal facets of CeO₂ , and vastly different behaviors on the single-atomic dispersion of surface Pd atoms are surprisingly discovered. In situ X-ray photoelectron spectroscopy (XPS), in situ near-ambient-pressure-XPS (NAP-XPS), in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and X-ray absorption spectroscopy (XAS) reveal that, in a reducing atmosphere, more oxygen vacancies are generated on the (100) facet of CeO₂ , and Pd atoms can be trapped and thus feature atomic dispersion; by contrast, on the CeO₂ (111) facet, Pd atoms will readily aggregate into clusters (Pd_n ). Furthermore, Pd₁ /CeO₂ (100) gives a high selectivity of 90.3% for the catalytic N-alkylation reaction, which is 2.8 times higher than that for Pd_n /CeO₂ (111). This direct evidence demonstrates the crucial role of crystal-facet effects in the preparation of metal-atom-on-metal-oxide SACs. This work thus opens an avenue for the rational design and targeted synthesis of ultrastable and sinter-resistant SACs.

Keywords: N-alkylation reaction; crystal-facets; oxygen defects, Pd-CeO 2; single-atom catalysis.

Abstract

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