Catalysis on Singly Dispersed Rh Atoms Anchored on an Inert Support

Shiran Zhang; Yan Tang; Luan Nguyen; Ya Fan Zhao; Zili Wu; Tian Wei Goh; Jimmy Jingyue Liu; Yuanyuan Li; Tong Zhu; Wenyu Huang; Anatoly I. Frenkel; Jun Li; Franklin Feng Tao

doi:10.1021/acscatal.7b01788

Catalysis on Singly Dispersed Rh Atoms Anchored on an Inert Support

Shiran Zhang, Yan Tang, Luan Nguyen, Ya Fan Zhao, Zili Wu, Tian Wei Goh, Jimmy Jingyue Liu, Yuanyuan Li, Tong Zhu, Wenyu Huang, Anatoly I. Frenkel, Jun Li, Franklin Feng Tao

Surface Chemistry & Catalysis Group

Research output: Contribution to journal › Article › peer-review

99 Scopus citations

Abstract

A metal catalyst supported on an inert substrate could consist of both metal nanoparticles and singly dispersed metal atoms. Whether these singly dispersed metal atoms are active and how different their catalytic mechanism could be in contrast to a supported metal catalyst are fundamentally important for understanding catalysis on a supported metal or oxide. By taking reduction of NO with CO on singly dispersed Rh atoms anchored on an inert support SiO₂ as a probe system (Rh₁/SiO₂), here we demonstrated how singly dispersed metal atoms on an inert support could perform a complex multi-step catalytic cycle through a mechanism distinctly different from that for a supported metal nanoparticle with continuously packed metal sites. These singly dispersed Rh₁ atoms anchored on SiO₂ are active in reducing nitric oxide with carbon monoxide through two reaction pathways that are different from those of Rh nanoparticles. In situ IR studies show that a CO molecule and a NO molecule coadsorb on a singly dispersed Rh atom, Rh₁ anchored on SiO₂, and couple to form an N atom to adsorb on the surface and a CO₂ molecule to desorb. The adsorbed N atom further couples with another CO molecule in the gas phase to form an intermediate -NCO on Rh₁; this intermediate can directly couple with an NO molecule adsorbed on the same Rh₁ to form N₂ and CO₂. In another pathway, the adsorbed N atom can couple with a coadsorbed NO on the same Rh₁ to form N₂O; N₂O further reacts with adsorbed CO on the same Rh₁ to form N₂ and CO₂ through a high activation barrier that can be overcome at a high temperature. Our studies show that the singly dispersed metal atoms on an inert support have great potential to perform selective transformation of chemicals. The confirmed catalysis with a singly dispersed Rh₁ on SiO₂ through a mechanism different from a metal nanoparticle supported on the same substrate suggests the significance of taking the single-atom catalysis (SAC) into fundamental studies of catalysis of a supported metal catalyst, since metal nanoparticles and singly dispersed metal atoms likely coexist on the inert support of many supported catalysts.

Original language	English
Pages (from-to)	110-121
Number of pages	12
Journal	ACS Catalysis
Volume	8
Issue number	1
DOIs	https://doi.org/10.1021/acscatal.7b01788
State	Published - Jan 5 2018

Funding

The work started at University of Kansas. Most experimental studies were performed at University of Kansas and this work was mainly funded by Chemical Sciences, Geosciences and Biosciences Division, Office of Basic Energy Sciences, Office of Science, U.S. Department of Energy, under Grant No. DESC0014561. S.Z., Y.T., L.N., T.Z., and F.T. were supported by the DOE Grant No. DE-SC0014561. Computational studies were performed in Jun Li group at Tsinghua University. Some IR spectra were collected at Z.W. lab at the Center for Understanding and Control of Acid Gas-Induced Evolution of Materials for Energy (UNCAGE-ME), an Energy Frontier Research Center funded by U.S. Department of Energy, Office of Science, Basic Energy Sciences Energy Sciences. S.Z was partially supported by National Science Foundation under the grant NSF-CHE-1462121. The theoretical work was supported by the National Natural Science Foundation of China to J.L. (NSFC Grant Nos. 91645203 and 21590792). J.(J.)L. acknowledges financial support from the National Science Foundation under CHE-1465057 and the use of the John M. Cowley Center for High Resolution Electron Microscopy at Arizona State University. The calculations were performed by using supercomputers at Tsinghua National Laboratory for Information Science and Technology and the Supercomputing Center of Computer Network Information Center of the Chinese Academy of Sciences. We also acknowledge support from the U.S. Department of Energy Grant No. DE-FG02-03ER15476 and Synchrotron Catalysis Consortium (U.S. Department of Energy, Office of Basic Energy Sciences, Grant No. DE-SC0012335). W.H. and T.-W.G. acknowledge the support from the donors of the American Chemical Society Petroleum Research Fund, for partial support of this research.

Keywords

density functional theory
in situ
infrared spectroscopy
insert support
operando
reduction of nitric oxide
rhodium
single-atom catalysis
singly dispersed metal atom

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10.1021/acscatal.7b01788

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title = "Catalysis on Singly Dispersed Rh Atoms Anchored on an Inert Support",

abstract = "A metal catalyst supported on an inert substrate could consist of both metal nanoparticles and singly dispersed metal atoms. Whether these singly dispersed metal atoms are active and how different their catalytic mechanism could be in contrast to a supported metal catalyst are fundamentally important for understanding catalysis on a supported metal or oxide. By taking reduction of NO with CO on singly dispersed Rh atoms anchored on an inert support SiO2 as a probe system (Rh1/SiO2), here we demonstrated how singly dispersed metal atoms on an inert support could perform a complex multi-step catalytic cycle through a mechanism distinctly different from that for a supported metal nanoparticle with continuously packed metal sites. These singly dispersed Rh1 atoms anchored on SiO2 are active in reducing nitric oxide with carbon monoxide through two reaction pathways that are different from those of Rh nanoparticles. In situ IR studies show that a CO molecule and a NO molecule coadsorb on a singly dispersed Rh atom, Rh1 anchored on SiO2, and couple to form an N atom to adsorb on the surface and a CO2 molecule to desorb. The adsorbed N atom further couples with another CO molecule in the gas phase to form an intermediate -NCO on Rh1; this intermediate can directly couple with an NO molecule adsorbed on the same Rh1 to form N2 and CO2. In another pathway, the adsorbed N atom can couple with a coadsorbed NO on the same Rh1 to form N2O; N2O further reacts with adsorbed CO on the same Rh1 to form N2 and CO2 through a high activation barrier that can be overcome at a high temperature. Our studies show that the singly dispersed metal atoms on an inert support have great potential to perform selective transformation of chemicals. The confirmed catalysis with a singly dispersed Rh1 on SiO2 through a mechanism different from a metal nanoparticle supported on the same substrate suggests the significance of taking the single-atom catalysis (SAC) into fundamental studies of catalysis of a supported metal catalyst, since metal nanoparticles and singly dispersed metal atoms likely coexist on the inert support of many supported catalysts.",

keywords = "density functional theory, in situ, infrared spectroscopy, insert support, operando, reduction of nitric oxide, rhodium, single-atom catalysis, singly dispersed metal atom",

author = "Shiran Zhang and Yan Tang and Luan Nguyen and Zhao, \{Ya Fan\} and Zili Wu and Goh, \{Tian Wei\} and Liu, \{Jimmy Jingyue\} and Yuanyuan Li and Tong Zhu and Wenyu Huang and Frenkel, \{Anatoly I.\} and Jun Li and Tao, \{Franklin Feng\}",

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T1 - Catalysis on Singly Dispersed Rh Atoms Anchored on an Inert Support

AU - Zhang, Shiran

AU - Tang, Yan

AU - Nguyen, Luan

AU - Zhao, Ya Fan

AU - Wu, Zili

AU - Goh, Tian Wei

AU - Liu, Jimmy Jingyue

AU - Li, Yuanyuan

AU - Zhu, Tong

AU - Huang, Wenyu

AU - Frenkel, Anatoly I.

AU - Li, Jun

AU - Tao, Franklin Feng

PY - 2018/1/5

Y1 - 2018/1/5

N2 - A metal catalyst supported on an inert substrate could consist of both metal nanoparticles and singly dispersed metal atoms. Whether these singly dispersed metal atoms are active and how different their catalytic mechanism could be in contrast to a supported metal catalyst are fundamentally important for understanding catalysis on a supported metal or oxide. By taking reduction of NO with CO on singly dispersed Rh atoms anchored on an inert support SiO2 as a probe system (Rh1/SiO2), here we demonstrated how singly dispersed metal atoms on an inert support could perform a complex multi-step catalytic cycle through a mechanism distinctly different from that for a supported metal nanoparticle with continuously packed metal sites. These singly dispersed Rh1 atoms anchored on SiO2 are active in reducing nitric oxide with carbon monoxide through two reaction pathways that are different from those of Rh nanoparticles. In situ IR studies show that a CO molecule and a NO molecule coadsorb on a singly dispersed Rh atom, Rh1 anchored on SiO2, and couple to form an N atom to adsorb on the surface and a CO2 molecule to desorb. The adsorbed N atom further couples with another CO molecule in the gas phase to form an intermediate -NCO on Rh1; this intermediate can directly couple with an NO molecule adsorbed on the same Rh1 to form N2 and CO2. In another pathway, the adsorbed N atom can couple with a coadsorbed NO on the same Rh1 to form N2O; N2O further reacts with adsorbed CO on the same Rh1 to form N2 and CO2 through a high activation barrier that can be overcome at a high temperature. Our studies show that the singly dispersed metal atoms on an inert support have great potential to perform selective transformation of chemicals. The confirmed catalysis with a singly dispersed Rh1 on SiO2 through a mechanism different from a metal nanoparticle supported on the same substrate suggests the significance of taking the single-atom catalysis (SAC) into fundamental studies of catalysis of a supported metal catalyst, since metal nanoparticles and singly dispersed metal atoms likely coexist on the inert support of many supported catalysts.

AB - A metal catalyst supported on an inert substrate could consist of both metal nanoparticles and singly dispersed metal atoms. Whether these singly dispersed metal atoms are active and how different their catalytic mechanism could be in contrast to a supported metal catalyst are fundamentally important for understanding catalysis on a supported metal or oxide. By taking reduction of NO with CO on singly dispersed Rh atoms anchored on an inert support SiO2 as a probe system (Rh1/SiO2), here we demonstrated how singly dispersed metal atoms on an inert support could perform a complex multi-step catalytic cycle through a mechanism distinctly different from that for a supported metal nanoparticle with continuously packed metal sites. These singly dispersed Rh1 atoms anchored on SiO2 are active in reducing nitric oxide with carbon monoxide through two reaction pathways that are different from those of Rh nanoparticles. In situ IR studies show that a CO molecule and a NO molecule coadsorb on a singly dispersed Rh atom, Rh1 anchored on SiO2, and couple to form an N atom to adsorb on the surface and a CO2 molecule to desorb. The adsorbed N atom further couples with another CO molecule in the gas phase to form an intermediate -NCO on Rh1; this intermediate can directly couple with an NO molecule adsorbed on the same Rh1 to form N2 and CO2. In another pathway, the adsorbed N atom can couple with a coadsorbed NO on the same Rh1 to form N2O; N2O further reacts with adsorbed CO on the same Rh1 to form N2 and CO2 through a high activation barrier that can be overcome at a high temperature. Our studies show that the singly dispersed metal atoms on an inert support have great potential to perform selective transformation of chemicals. The confirmed catalysis with a singly dispersed Rh1 on SiO2 through a mechanism different from a metal nanoparticle supported on the same substrate suggests the significance of taking the single-atom catalysis (SAC) into fundamental studies of catalysis of a supported metal catalyst, since metal nanoparticles and singly dispersed metal atoms likely coexist on the inert support of many supported catalysts.

KW - density functional theory

KW - in situ

KW - infrared spectroscopy

KW - insert support

KW - operando

KW - reduction of nitric oxide

KW - rhodium

KW - single-atom catalysis

KW - singly dispersed metal atom

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DO - 10.1021/acscatal.7b01788

M3 - Article

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SN - 2155-5435

VL - 8

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EP - 121

JO - ACS Catalysis

JF - ACS Catalysis

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ER -

Catalysis on Singly Dispersed Rh Atoms Anchored on an Inert Support

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Keywords

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