Botao Qiao - Academia.edu (original) (raw)
Papers by Botao Qiao
Science advances, 2017
Supported metal catalysts play a central role in the modern chemical industry but often exhibit p... more Supported metal catalysts play a central role in the modern chemical industry but often exhibit poor on-stream stability. The strong metal-support interaction (SMSI) offers a route to control the structural properties of supported metals and, hence, their reactivity and stability. Conventional wisdom holds that supported Au cannot manifest a classical SMSI, which is characterized by reversible metal encapsulation by the support upon high-temperature redox treatments. We demonstrate a classical SMSI for Au/TiO2, evidenced by suppression of CO adsorption, electron transfer from TiO2 to Au nanoparticles, and gold encapsulation by a TiO x overlayer following high-temperature reduction (reversed by subsequent oxidation), akin to that observed for titania-supported platinum group metals. In the SMSI state, Au/TiO2 exhibits markedly improved stability toward CO oxidation. The SMSI extends to Au supported over other reducible oxides (Fe3O4 and CeO2) and other group IB metals (Cu and Ag) ove...
Angewandte Chemie International Edition, 2016
Journal of Energy Chemistry, 2016
The Journal of Physical Chemistry C, Sep 25, 2014
Angewandte Chemie (International ed. in English), Jan 21, 2016
The discovery that gold catalysts could be active for CO oxidation at cryogenic temperatures has ... more The discovery that gold catalysts could be active for CO oxidation at cryogenic temperatures has ignited much excitement in nanocatalysis. Whether the alternative Pt group metal (PGM) catalysts can exhibit such high performance is an interesting research issue. So far, no PGM catalyst shows activity for CO oxidation at cryogenic temperatures. In this work, we report a sub-nano Rh/TiO2 catalyst that can completely convert CO at 223 K. This catalyst exhibits at least three orders of magnitude higher turnover frequency (TOF) than the best Rh-based catalysts and comparable to the well-known Au/TiO2 for CO oxidation. The specific size range of 0.4-0.8 nm Rh clusters is critical to the facile activation of O2 over the Rh-TiO2 interface in a form of Rh-O-O-Ti (superoxide). This superoxide is ready to react with the CO adsorbed on TiO2 sites at cryogenic temperatures.
Journal of the American Chemical Society, 2015
The strong metal-support interaction (SMSI) is of great importance for supported catalysts in het... more The strong metal-support interaction (SMSI) is of great importance for supported catalysts in heterogeneous catalysis. Here we report the first example of SMSI between Au nanoparticles (NPs) and hydroxyapatite (HAP), a non-oxide. The reversible encapsulation of Au NPs by HAP support, electron transfer and changes in CO adsorption are identical to the classic SMSI except that the SMSI of Au/HAP occurred under oxidative condition-the opposite condition for the classical SMSI. The SMSI of Au/HAP not only enhanced the sintering resistance of Au NPs upon calcination but also improved their selectivity and reusability in liquid-phase reaction. It was found that the SMSI between Au and HAP is general and could be extended to other phosphate supported Au systems such as Au/LaPO4. This new discovery may open a new way to design and develop highly stable supported Au catalysts with controllable activity and selectivity.
Journal of Catalysis, 2014
Fe(OH) x -supported noble metal catalysts exhibited good performance in low-temperature CO oxidat... more Fe(OH) x -supported noble metal catalysts exhibited good performance in low-temperature CO oxidation or CO preferential oxidation (PROX), which usually resulted from the high reducibility of Fe(OH) x . However, we found here that the use of Fe(OH) x promoted the formation of OH species during PROX over Ir/Fe(OH) x catalysts, which not only greatly lowered the temperature for 100% CO conversion, even to room temperature, but also improved the stability. These OH species originated from the reaction between the adsorbed O on Fe 2+ sites and the adsorbed H on Ir sites. They changed the reaction route for the oxidation of CO through adsorbed CO and OH with lower activation energy (E a : 5.2kJ/mol)ratherthanthroughadsorbedCOandO(Ea:5.2 kJ/mol) rather than through adsorbed CO and O (E a : 5.2kJ/mol)ratherthanthroughadsorbedCOandO(Ea:15.4 kJ/mol). With further time-resolved mass spectroscopy and diffuse reflectance infrared spectroscopy, the OH species, prior to the adsorbed O, were proved to react with CO directly.
Chinese Journal of Catalysis, 2015
Chem. Commun., 2015
Supported Au nanoparticles (NPs) sinter easily. Anchoring Au NPs is of fundamental interest and p... more Supported Au nanoparticles (NPs) sinter easily. Anchoring Au NPs is of fundamental interest and practical importance. We stabilized Au NPs by growing them hetero-epitaxially into the facets of ZnO nanowires. The sintering of epitaxially anchored Au NPs was significantly reduced at high calcination temperatures and during CO oxidation.
Chinese Journal of Catalysis, 2013
Advanced Functional Materials, 2015
Chemical communications (Cambridge, England), Jan 10, 2015
A FeOx supported Pt single-atom catalyst (Pt-SAC) exhibited much higher NO conversion and selecti... more A FeOx supported Pt single-atom catalyst (Pt-SAC) exhibited much higher NO conversion and selectivity to N2 than the supported Pt nanocatalyst (Pt-Nano). This better performance was attributed to not only the stronger NO adsorption and easier dissociation of the N-O bond but also the presence of more oxygen vacancies on the Pt-SAC.
ACS Catalysis, 2014
Pt single atoms and small clusters were dispersed on iron oxides by a facile coprecipitation meth... more Pt single atoms and small clusters were dispersed on iron oxides by a facile coprecipitation method. These catalysts, with or without calcination at elevated temperatures, show excellent activity and selectivity for preferential oxidation of CO in the H 2 -rich gas. They can completely remove CO from H 2rich gas at a wide temperature range of 20−70°C, which renders them suitable for low-temperature applications. The reaction followed a mixture of competitive mechanism and a noncompetitive/redox mechanism. The weakened CO adsorption on small Pt clusters and atoms makes the competitive adsorption of O 2 feasible, which ensures a high activity of Pt/Fe catalysts, even calcined at elevated temperature.
Nature Communications, 2014
The catalytic hydrogenation of nitroarenes is an environmentally benign technology for the produc... more The catalytic hydrogenation of nitroarenes is an environmentally benign technology for the production of anilines, which are key intermediates for manufacturing agrochemicals, pharmaceuticals and dyes. Most of the precious metal catalysts, however, suffer from low chemoselectivity when one or more reducible groups are present in a nitroarene molecule. Herein we report FeO x -supported platinum single-atom and pseudo-single-atom structures as highly active, chemoselective and reusable catalysts for hydrogenation of a variety of substituted nitroarenes. For hydrogenation of 3-nitrostyrene, the catalyst yields a TOF of B1,500 h À 1 , 20-fold higher than the best result reported in literature, and a selectivity to 3-aminostyrene close to 99%, the best ever achieved over platinum group metals. The superior performance can be attributed to the presence of positively charged platinum centres and the absence of Pt-Pt metallic bonding, both of which favour the preferential adsorption of nitro groups.
Nature Chemistry, 2011
Platinum-based heterogeneous catalysts are critical to many important commercial chemical process... more Platinum-based heterogeneous catalysts are critical to many important commercial chemical processes, but their efficiency is extremely low on a per metal atom basis, because only the surface active-site atoms are used. Catalysts with singleatom dispersions are thus highly desirable to maximize atom efficiency, but making them is challenging. Here we report the synthesis of a single-atom catalyst that consists of only isolated single Pt atoms anchored to the surfaces of iron oxide nanocrystallites. This single-atom catalyst has extremely high atom efficiency and shows excellent stability and high activity for both CO oxidation and preferential oxidation of CO in H 2 . Density functional theory calculations show that the high catalytic activity correlates with the partially vacant 5d orbitals of the positively charged, high-valent Pt atoms, which help to reduce both the CO adsorption energy and the activation barriers for CO oxidation.
Microscopy and Microanalysis, 2012
Science advances, 2017
Supported metal catalysts play a central role in the modern chemical industry but often exhibit p... more Supported metal catalysts play a central role in the modern chemical industry but often exhibit poor on-stream stability. The strong metal-support interaction (SMSI) offers a route to control the structural properties of supported metals and, hence, their reactivity and stability. Conventional wisdom holds that supported Au cannot manifest a classical SMSI, which is characterized by reversible metal encapsulation by the support upon high-temperature redox treatments. We demonstrate a classical SMSI for Au/TiO2, evidenced by suppression of CO adsorption, electron transfer from TiO2 to Au nanoparticles, and gold encapsulation by a TiO x overlayer following high-temperature reduction (reversed by subsequent oxidation), akin to that observed for titania-supported platinum group metals. In the SMSI state, Au/TiO2 exhibits markedly improved stability toward CO oxidation. The SMSI extends to Au supported over other reducible oxides (Fe3O4 and CeO2) and other group IB metals (Cu and Ag) ove...
Angewandte Chemie International Edition, 2016
Journal of Energy Chemistry, 2016
The Journal of Physical Chemistry C, Sep 25, 2014
Angewandte Chemie (International ed. in English), Jan 21, 2016
The discovery that gold catalysts could be active for CO oxidation at cryogenic temperatures has ... more The discovery that gold catalysts could be active for CO oxidation at cryogenic temperatures has ignited much excitement in nanocatalysis. Whether the alternative Pt group metal (PGM) catalysts can exhibit such high performance is an interesting research issue. So far, no PGM catalyst shows activity for CO oxidation at cryogenic temperatures. In this work, we report a sub-nano Rh/TiO2 catalyst that can completely convert CO at 223 K. This catalyst exhibits at least three orders of magnitude higher turnover frequency (TOF) than the best Rh-based catalysts and comparable to the well-known Au/TiO2 for CO oxidation. The specific size range of 0.4-0.8 nm Rh clusters is critical to the facile activation of O2 over the Rh-TiO2 interface in a form of Rh-O-O-Ti (superoxide). This superoxide is ready to react with the CO adsorbed on TiO2 sites at cryogenic temperatures.
Journal of the American Chemical Society, 2015
The strong metal-support interaction (SMSI) is of great importance for supported catalysts in het... more The strong metal-support interaction (SMSI) is of great importance for supported catalysts in heterogeneous catalysis. Here we report the first example of SMSI between Au nanoparticles (NPs) and hydroxyapatite (HAP), a non-oxide. The reversible encapsulation of Au NPs by HAP support, electron transfer and changes in CO adsorption are identical to the classic SMSI except that the SMSI of Au/HAP occurred under oxidative condition-the opposite condition for the classical SMSI. The SMSI of Au/HAP not only enhanced the sintering resistance of Au NPs upon calcination but also improved their selectivity and reusability in liquid-phase reaction. It was found that the SMSI between Au and HAP is general and could be extended to other phosphate supported Au systems such as Au/LaPO4. This new discovery may open a new way to design and develop highly stable supported Au catalysts with controllable activity and selectivity.
Journal of Catalysis, 2014
Fe(OH) x -supported noble metal catalysts exhibited good performance in low-temperature CO oxidat... more Fe(OH) x -supported noble metal catalysts exhibited good performance in low-temperature CO oxidation or CO preferential oxidation (PROX), which usually resulted from the high reducibility of Fe(OH) x . However, we found here that the use of Fe(OH) x promoted the formation of OH species during PROX over Ir/Fe(OH) x catalysts, which not only greatly lowered the temperature for 100% CO conversion, even to room temperature, but also improved the stability. These OH species originated from the reaction between the adsorbed O on Fe 2+ sites and the adsorbed H on Ir sites. They changed the reaction route for the oxidation of CO through adsorbed CO and OH with lower activation energy (E a : 5.2kJ/mol)ratherthanthroughadsorbedCOandO(Ea:5.2 kJ/mol) rather than through adsorbed CO and O (E a : 5.2kJ/mol)ratherthanthroughadsorbedCOandO(Ea:15.4 kJ/mol). With further time-resolved mass spectroscopy and diffuse reflectance infrared spectroscopy, the OH species, prior to the adsorbed O, were proved to react with CO directly.
Chinese Journal of Catalysis, 2015
Chem. Commun., 2015
Supported Au nanoparticles (NPs) sinter easily. Anchoring Au NPs is of fundamental interest and p... more Supported Au nanoparticles (NPs) sinter easily. Anchoring Au NPs is of fundamental interest and practical importance. We stabilized Au NPs by growing them hetero-epitaxially into the facets of ZnO nanowires. The sintering of epitaxially anchored Au NPs was significantly reduced at high calcination temperatures and during CO oxidation.
Chinese Journal of Catalysis, 2013
Advanced Functional Materials, 2015
Chemical communications (Cambridge, England), Jan 10, 2015
A FeOx supported Pt single-atom catalyst (Pt-SAC) exhibited much higher NO conversion and selecti... more A FeOx supported Pt single-atom catalyst (Pt-SAC) exhibited much higher NO conversion and selectivity to N2 than the supported Pt nanocatalyst (Pt-Nano). This better performance was attributed to not only the stronger NO adsorption and easier dissociation of the N-O bond but also the presence of more oxygen vacancies on the Pt-SAC.
ACS Catalysis, 2014
Pt single atoms and small clusters were dispersed on iron oxides by a facile coprecipitation meth... more Pt single atoms and small clusters were dispersed on iron oxides by a facile coprecipitation method. These catalysts, with or without calcination at elevated temperatures, show excellent activity and selectivity for preferential oxidation of CO in the H 2 -rich gas. They can completely remove CO from H 2rich gas at a wide temperature range of 20−70°C, which renders them suitable for low-temperature applications. The reaction followed a mixture of competitive mechanism and a noncompetitive/redox mechanism. The weakened CO adsorption on small Pt clusters and atoms makes the competitive adsorption of O 2 feasible, which ensures a high activity of Pt/Fe catalysts, even calcined at elevated temperature.
Nature Communications, 2014
The catalytic hydrogenation of nitroarenes is an environmentally benign technology for the produc... more The catalytic hydrogenation of nitroarenes is an environmentally benign technology for the production of anilines, which are key intermediates for manufacturing agrochemicals, pharmaceuticals and dyes. Most of the precious metal catalysts, however, suffer from low chemoselectivity when one or more reducible groups are present in a nitroarene molecule. Herein we report FeO x -supported platinum single-atom and pseudo-single-atom structures as highly active, chemoselective and reusable catalysts for hydrogenation of a variety of substituted nitroarenes. For hydrogenation of 3-nitrostyrene, the catalyst yields a TOF of B1,500 h À 1 , 20-fold higher than the best result reported in literature, and a selectivity to 3-aminostyrene close to 99%, the best ever achieved over platinum group metals. The superior performance can be attributed to the presence of positively charged platinum centres and the absence of Pt-Pt metallic bonding, both of which favour the preferential adsorption of nitro groups.
Nature Chemistry, 2011
Platinum-based heterogeneous catalysts are critical to many important commercial chemical process... more Platinum-based heterogeneous catalysts are critical to many important commercial chemical processes, but their efficiency is extremely low on a per metal atom basis, because only the surface active-site atoms are used. Catalysts with singleatom dispersions are thus highly desirable to maximize atom efficiency, but making them is challenging. Here we report the synthesis of a single-atom catalyst that consists of only isolated single Pt atoms anchored to the surfaces of iron oxide nanocrystallites. This single-atom catalyst has extremely high atom efficiency and shows excellent stability and high activity for both CO oxidation and preferential oxidation of CO in H 2 . Density functional theory calculations show that the high catalytic activity correlates with the partially vacant 5d orbitals of the positively charged, high-valent Pt atoms, which help to reduce both the CO adsorption energy and the activation barriers for CO oxidation.
Microscopy and Microanalysis, 2012