Hongmo Li | Georgia Institute of Technology (original) (raw)
Papers by Hongmo Li
arXiv (Cornell University), Jan 5, 2021
Frenkel excitons, the primary photoexcitations in organic semiconductors that are unequivocally r... more Frenkel excitons, the primary photoexcitations in organic semiconductors that are unequivocally responsible for the optical properties of this materials class, are predicted to form bound exciton pairs, i.e., biexcitons. These are key intermediates, ubiquitous in many relevant photophysical processes; for example, they determine the exciton bimolecular annihilation dynamics in such systems. Deciphering the details of biexciton correlations is, thus, of utmost importance to understand the optical processes in these semiconductors. To date, however, due to their spectral ambiguity, there has been only scant direct evidence of bound biexcitons, limiting the insights that can be gained. Moreover, a quantum-mechanical basis describing biexciton correlation/stability has so far been lacking. By employing nonlinear coherent spectroscopy, we identify here bound biexcitons in a model polymeric semiconductor. We find, unexpectedly, that excitons with interchain vibronic dispersion reveal intrachain biexciton correlations and vice versa. Moreover, using a Frenkel exciton model, we can relate the biexciton binding energy to molecular parameters quantified by quantum chemistry, including the magnitude and sign of the exciton-exciton interaction the inter-site hopping energies. Therefore, our work promises a window towards general insights into the many-body electronic structure in polymeric semiconductors and beyond; e.g., other excitonic systems such as organic semiconductor crystals, molecular aggregates, photosynthetic lightharvesting complexes, or DNA.
Gold has been widely used for the contacts in electrical connectors. However, people are searchin... more Gold has been widely used for the contacts in electrical connectors. However, people are searching for the substitute of gold due to its high cost. Nickel is considered as the ideal metal to replace gold since the former has a number of superior properties. Electroplating nickel from Watts bath is the prevalent method for nickel production, but boron compounds are harmful to environment. Sodium citrate can be an environmentally friendly alternative to boric acid. In this research, nanocrystalline Ni deposits with different grain sizes were electrodeposited from citrate bath. The effects of sodium citrate concentration, current density and pH on the electrodeposited Ni properties were analyzed. The cathodic current efficiency decreased with the increase of sodium citrate due to the complexation of Ni2+ and citrate ions. Sodium citrate influenced the orientation and grain size of nickel deposits. The corrosion resistance of nickel deposits from citrate baths is comparable to that of boric acid baths. The corrosion resistance of Ni coatings in 1 mol•L−1 H2SO4 increased when the grain size decreased from 43.9 nm to 25.7 nm because of the faster formation of Ni(OH)2 passive films.
Nanotechnology, Oct 11, 2016
SiO2-Ag-SiO2, a sandwiched core/shell structure with a layer of Ag nanoparticles (∼4 nm) encapsul... more SiO2-Ag-SiO2, a sandwiched core/shell structure with a layer of Ag nanoparticles (∼4 nm) encapsulated between a shallow SiO2 surface layer and a SiO2 submicrosphere substrate (∼200 nm), has been synthesized from [Formula: see text] and SiO2 spheres by a facile one-pot hydrothermal method. The composite is proposed to result from the dynamic balance between the [Formula: see text] reduction and the dissolution-redeposition of SiO2 in mild basic media. The synthetic mechanism and the roles of the reaction time, temperature, and the amount of ammonia in the formation of this unique structure are investigated and discussed. The composite structure shows superior catalytic performance in CO oxidation to the control Ag/SiO2 structure prepared by impregnation. Pre-treatment by O2 at 600 °C significantly improves the catalytic performance of the composite structure and preserves the nanocomposite structure well.
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, Jul 1, 2016
Abstract A bulk ultrafine grained Cu-1.2 vol%NbC-7.1 vol%C nanocomposite was fabricated by combin... more Abstract A bulk ultrafine grained Cu-1.2 vol%NbC-7.1 vol%C nanocomposite was fabricated by combining high energy mechanical milling from a mixture of Cu, graphite and Nb powders with spark plasma sintering and hot extrusion of the milled powder. The microstructure of the ultrafine grained Cu matrix nanocomposite consisted of equiaxed ultrafine Cu grains, NbC nanoparticles mainly inside the Cu grains, and C particles along the Cu grain boundaries. The thermal stability of the microstructure of the ultrafine grained Cu matrix nanocomposite during 1 h isochronal annealing at temperatures ranging from 750 to 1050 °C was investigated, and we found that the ultrafine grained microstructure of the Cu matrix exhibited excellent thermal stability. With annealing the extruded sample for 1 h at 1050 °C (0.98T m , where T m is the melting point of Cu in Kelvin scale), the average Cu grain size just slightly increased from 126 to 157 nm, the NbC nanoparticles had an average size of about 8 nm, and the average size of the C particles increased significantly from 68 to 109 nm. The very high thermal stability of the microstructure of the ultrafine grained Cu matrix during annealing at the elevated temperature close to its melting point can be attributed to the suppression effect of both intragranular NbC nanoparticles and intergranular C particles on Cu grain growth. Based on this investigation, considerations to be made in selecting intragranular nanoparticles and intergranular particles for stabilizing the microstructures of nanocrystalline and ultrafine grained metals and achieving superior strength are proposed.
Presented online April 9, 2021, 3:00 p.m.-4:40 p.m.Since 2015, Tech’s version of this internation... more Presented online April 9, 2021, 3:00 p.m.-4:40 p.m.Since 2015, Tech’s version of this international competition, which started at The University of Queensland, Australia, has provided graduate students with an opportunity to hone their professional skills and win prize money to help further their research efforts. The competition challenges students to explain their research in three minutes in a way that anyone can understand.Hosts (Members of Georgia Institute of Technology): Jeff Garbers, Enterprise Innovation Institute, Venture Lab; Bonnie H. Ferri, Vice Provost for Graduate Education and Faculty Development; James Black, Assistant Director of Strategic Initiatives and Grad Life, Office of Graduate Studies; and Leslie Sharp, Dean of the Library.Judges: Ashley Bush, Director, Communications and Employee Engagement, Southwire Company, LLC; Duffie Dixon, Owner, Duffie Dixon Media; Charles Edwards, Coaching Practice Lead, Jackson Spalding; Dene Sheheane, President, Georgia Tech Alum...
School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlant... more School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, GA 30332, United States School of Materials Science and Engineering, Georgia Institute of Technology, North Avenue, Atlanta, GA 30332, United States Department of Physics and Center for Functional Materials, Wake Forest University, 1834 Wake Forest Road, Winston-Salem, NC 27109, United States Department of Chemistry, University of Houston, Houston, Texas 77204, United States 5 School of Chemical and Biomolecular Engineering, 311 Ferst Drive NW, Atlanta, GA 30332, United States Theoretical Division & Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545, United States School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332, United States
ACS Applied Materials & Interfaces
Doping conjugated polymers, which are potential candidates for the next generation of organic ele... more Doping conjugated polymers, which are potential candidates for the next generation of organic electronics, is an effective strategy for manipulating their electrical conductivity. However, selecting a suitable polymer−dopant combination is exceptionally challenging because of the vastness of the chemical, configurational, and morphological spaces one needs to search. In this work, high-performance surrogate models, trained on available experimentally measured data, are developed to predict the p-type electrical conductivity and are used to screen a large candidate hypothetical data set of more than 800 000 polymer−dopant combinations. Promising candidates are identified for synthesis and device fabrication. Additionally, new design guidelines are extracted that verify and extend knowledge on important molecular fragments that correlate to high conductivity. Conductivity prediction models are also deployed at www.polymergenome.org for broader open-access community use.
School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlant... more School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, GA 30332, United States School of Materials Science and Engineering, Georgia Institute of Technology, North Avenue, Atlanta, GA 30332, United States Department of Physics and Center for Functional Materials, Wake Forest University, 1834 Wake Forest Road, Winston-Salem, NC 27109, United States 4 School of Chemical and Biomolecular Engineering, 311 Ferst Drive NW, Atlanta, GA 30332, United States Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, United States Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545, United States Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545, United States Department of Chemistry, University of Houston, Houston, Texas 77204, United States School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332, United States
Gold has been widely used for the contacts in electrical connectors. However, people are searchin... more Gold has been widely used for the contacts in electrical connectors. However, people are searching for the substitute of gold due to its high cost. Nickel is considered as the ideal metal to replace gold since the former has a number of superior properties. Electroplating nickel from Watts bath is the prevalent method for nickel production, but boron compounds are harmful to environment. Sodium citrate can be an environmentally friendly alternative to boric acid. In this research, nanocrystalline Ni deposits with different grain sizes were electrodeposited from citrate bath. The effects of sodium citrate concentration, current density and pH on the electrodeposited Ni properties were analyzed. The cathodic current efficiency decreased with the increase of sodium citrate due to the complexation of Ni2+ and citrate ions. Sodium citrate influenced the orientation and grain size of nickel deposits. The corrosion resistance of nickel deposits from citrate baths is comparable to that of b...
Proceedings of the 1st International Conference on Advances in Organic and Hybrid Electronic Materials
Materials Science and Engineering: A
Nanotechnology, Jan 11, 2016
SiO2-Ag-SiO2, a sandwiched core/shell structure with a layer of Ag nanoparticles (∼4 nm) encapsul... more SiO2-Ag-SiO2, a sandwiched core/shell structure with a layer of Ag nanoparticles (∼4 nm) encapsulated between a shallow SiO2 surface layer and a SiO2 submicrosphere substrate (∼200 nm), has been synthesized from [Formula: see text] and SiO2 spheres by a facile one-pot hydrothermal method. The composite is proposed to result from the dynamic balance between the [Formula: see text] reduction and the dissolution-redeposition of SiO2 in mild basic media. The synthetic mechanism and the roles of the reaction time, temperature, and the amount of ammonia in the formation of this unique structure are investigated and discussed. The composite structure shows superior catalytic performance in CO oxidation to the control Ag/SiO2 structure prepared by impregnation. Pre-treatment by O2 at 600 °C significantly improves the catalytic performance of the composite structure and preserves the nanocomposite structure well.
Nanotechnology, Jan 11, 2016
SiO2-Ag-SiO2, a sandwiched core/shell structure with a layer of Ag nanoparticles (∼4 nm) encapsul... more SiO2-Ag-SiO2, a sandwiched core/shell structure with a layer of Ag nanoparticles (∼4 nm) encapsulated between a shallow SiO2 surface layer and a SiO2 submicrosphere substrate (∼200 nm), has been synthesized from [Formula: see text] and SiO2 spheres by a facile one-pot hydrothermal method. The composite is proposed to result from the dynamic balance between the [Formula: see text] reduction and the dissolution-redeposition of SiO2 in mild basic media. The synthetic mechanism and the roles of the reaction time, temperature, and the amount of ammonia in the formation of this unique structure are investigated and discussed. The composite structure shows superior catalytic performance in CO oxidation to the control Ag/SiO2 structure prepared by impregnation. Pre-treatment by O2 at 600 °C significantly improves the catalytic performance of the composite structure and preserves the nanocomposite structure well.
Nanotechnology, Jan 11, 2016
SiO2-Ag-SiO2, a sandwiched core/shell structure with a layer of Ag nanoparticles (∼4 nm) encapsul... more SiO2-Ag-SiO2, a sandwiched core/shell structure with a layer of Ag nanoparticles (∼4 nm) encapsulated between a shallow SiO2 surface layer and a SiO2 submicrosphere substrate (∼200 nm), has been synthesized from [Formula: see text] and SiO2 spheres by a facile one-pot hydrothermal method. The composite is proposed to result from the dynamic balance between the [Formula: see text] reduction and the dissolution-redeposition of SiO2 in mild basic media. The synthetic mechanism and the roles of the reaction time, temperature, and the amount of ammonia in the formation of this unique structure are investigated and discussed. The composite structure shows superior catalytic performance in CO oxidation to the control Ag/SiO2 structure prepared by impregnation. Pre-treatment by O2 at 600 °C significantly improves the catalytic performance of the composite structure and preserves the nanocomposite structure well.
arXiv (Cornell University), Jan 5, 2021
Frenkel excitons, the primary photoexcitations in organic semiconductors that are unequivocally r... more Frenkel excitons, the primary photoexcitations in organic semiconductors that are unequivocally responsible for the optical properties of this materials class, are predicted to form bound exciton pairs, i.e., biexcitons. These are key intermediates, ubiquitous in many relevant photophysical processes; for example, they determine the exciton bimolecular annihilation dynamics in such systems. Deciphering the details of biexciton correlations is, thus, of utmost importance to understand the optical processes in these semiconductors. To date, however, due to their spectral ambiguity, there has been only scant direct evidence of bound biexcitons, limiting the insights that can be gained. Moreover, a quantum-mechanical basis describing biexciton correlation/stability has so far been lacking. By employing nonlinear coherent spectroscopy, we identify here bound biexcitons in a model polymeric semiconductor. We find, unexpectedly, that excitons with interchain vibronic dispersion reveal intrachain biexciton correlations and vice versa. Moreover, using a Frenkel exciton model, we can relate the biexciton binding energy to molecular parameters quantified by quantum chemistry, including the magnitude and sign of the exciton-exciton interaction the inter-site hopping energies. Therefore, our work promises a window towards general insights into the many-body electronic structure in polymeric semiconductors and beyond; e.g., other excitonic systems such as organic semiconductor crystals, molecular aggregates, photosynthetic lightharvesting complexes, or DNA.
Gold has been widely used for the contacts in electrical connectors. However, people are searchin... more Gold has been widely used for the contacts in electrical connectors. However, people are searching for the substitute of gold due to its high cost. Nickel is considered as the ideal metal to replace gold since the former has a number of superior properties. Electroplating nickel from Watts bath is the prevalent method for nickel production, but boron compounds are harmful to environment. Sodium citrate can be an environmentally friendly alternative to boric acid. In this research, nanocrystalline Ni deposits with different grain sizes were electrodeposited from citrate bath. The effects of sodium citrate concentration, current density and pH on the electrodeposited Ni properties were analyzed. The cathodic current efficiency decreased with the increase of sodium citrate due to the complexation of Ni2+ and citrate ions. Sodium citrate influenced the orientation and grain size of nickel deposits. The corrosion resistance of nickel deposits from citrate baths is comparable to that of boric acid baths. The corrosion resistance of Ni coatings in 1 mol•L−1 H2SO4 increased when the grain size decreased from 43.9 nm to 25.7 nm because of the faster formation of Ni(OH)2 passive films.
Nanotechnology, Oct 11, 2016
SiO2-Ag-SiO2, a sandwiched core/shell structure with a layer of Ag nanoparticles (∼4 nm) encapsul... more SiO2-Ag-SiO2, a sandwiched core/shell structure with a layer of Ag nanoparticles (∼4 nm) encapsulated between a shallow SiO2 surface layer and a SiO2 submicrosphere substrate (∼200 nm), has been synthesized from [Formula: see text] and SiO2 spheres by a facile one-pot hydrothermal method. The composite is proposed to result from the dynamic balance between the [Formula: see text] reduction and the dissolution-redeposition of SiO2 in mild basic media. The synthetic mechanism and the roles of the reaction time, temperature, and the amount of ammonia in the formation of this unique structure are investigated and discussed. The composite structure shows superior catalytic performance in CO oxidation to the control Ag/SiO2 structure prepared by impregnation. Pre-treatment by O2 at 600 °C significantly improves the catalytic performance of the composite structure and preserves the nanocomposite structure well.
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, Jul 1, 2016
Abstract A bulk ultrafine grained Cu-1.2 vol%NbC-7.1 vol%C nanocomposite was fabricated by combin... more Abstract A bulk ultrafine grained Cu-1.2 vol%NbC-7.1 vol%C nanocomposite was fabricated by combining high energy mechanical milling from a mixture of Cu, graphite and Nb powders with spark plasma sintering and hot extrusion of the milled powder. The microstructure of the ultrafine grained Cu matrix nanocomposite consisted of equiaxed ultrafine Cu grains, NbC nanoparticles mainly inside the Cu grains, and C particles along the Cu grain boundaries. The thermal stability of the microstructure of the ultrafine grained Cu matrix nanocomposite during 1 h isochronal annealing at temperatures ranging from 750 to 1050 °C was investigated, and we found that the ultrafine grained microstructure of the Cu matrix exhibited excellent thermal stability. With annealing the extruded sample for 1 h at 1050 °C (0.98T m , where T m is the melting point of Cu in Kelvin scale), the average Cu grain size just slightly increased from 126 to 157 nm, the NbC nanoparticles had an average size of about 8 nm, and the average size of the C particles increased significantly from 68 to 109 nm. The very high thermal stability of the microstructure of the ultrafine grained Cu matrix during annealing at the elevated temperature close to its melting point can be attributed to the suppression effect of both intragranular NbC nanoparticles and intergranular C particles on Cu grain growth. Based on this investigation, considerations to be made in selecting intragranular nanoparticles and intergranular particles for stabilizing the microstructures of nanocrystalline and ultrafine grained metals and achieving superior strength are proposed.
Presented online April 9, 2021, 3:00 p.m.-4:40 p.m.Since 2015, Tech’s version of this internation... more Presented online April 9, 2021, 3:00 p.m.-4:40 p.m.Since 2015, Tech’s version of this international competition, which started at The University of Queensland, Australia, has provided graduate students with an opportunity to hone their professional skills and win prize money to help further their research efforts. The competition challenges students to explain their research in three minutes in a way that anyone can understand.Hosts (Members of Georgia Institute of Technology): Jeff Garbers, Enterprise Innovation Institute, Venture Lab; Bonnie H. Ferri, Vice Provost for Graduate Education and Faculty Development; James Black, Assistant Director of Strategic Initiatives and Grad Life, Office of Graduate Studies; and Leslie Sharp, Dean of the Library.Judges: Ashley Bush, Director, Communications and Employee Engagement, Southwire Company, LLC; Duffie Dixon, Owner, Duffie Dixon Media; Charles Edwards, Coaching Practice Lead, Jackson Spalding; Dene Sheheane, President, Georgia Tech Alum...
School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlant... more School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, GA 30332, United States School of Materials Science and Engineering, Georgia Institute of Technology, North Avenue, Atlanta, GA 30332, United States Department of Physics and Center for Functional Materials, Wake Forest University, 1834 Wake Forest Road, Winston-Salem, NC 27109, United States Department of Chemistry, University of Houston, Houston, Texas 77204, United States 5 School of Chemical and Biomolecular Engineering, 311 Ferst Drive NW, Atlanta, GA 30332, United States Theoretical Division & Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545, United States School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332, United States
ACS Applied Materials & Interfaces
Doping conjugated polymers, which are potential candidates for the next generation of organic ele... more Doping conjugated polymers, which are potential candidates for the next generation of organic electronics, is an effective strategy for manipulating their electrical conductivity. However, selecting a suitable polymer−dopant combination is exceptionally challenging because of the vastness of the chemical, configurational, and morphological spaces one needs to search. In this work, high-performance surrogate models, trained on available experimentally measured data, are developed to predict the p-type electrical conductivity and are used to screen a large candidate hypothetical data set of more than 800 000 polymer−dopant combinations. Promising candidates are identified for synthesis and device fabrication. Additionally, new design guidelines are extracted that verify and extend knowledge on important molecular fragments that correlate to high conductivity. Conductivity prediction models are also deployed at www.polymergenome.org for broader open-access community use.
School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlant... more School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, GA 30332, United States School of Materials Science and Engineering, Georgia Institute of Technology, North Avenue, Atlanta, GA 30332, United States Department of Physics and Center for Functional Materials, Wake Forest University, 1834 Wake Forest Road, Winston-Salem, NC 27109, United States 4 School of Chemical and Biomolecular Engineering, 311 Ferst Drive NW, Atlanta, GA 30332, United States Theoretical Division, Los Alamos National Laboratory, Los Alamos, NM 87545, United States Center for Nonlinear Studies, Los Alamos National Laboratory, Los Alamos, NM 87545, United States Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545, United States Department of Chemistry, University of Houston, Houston, Texas 77204, United States School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332, United States
Gold has been widely used for the contacts in electrical connectors. However, people are searchin... more Gold has been widely used for the contacts in electrical connectors. However, people are searching for the substitute of gold due to its high cost. Nickel is considered as the ideal metal to replace gold since the former has a number of superior properties. Electroplating nickel from Watts bath is the prevalent method for nickel production, but boron compounds are harmful to environment. Sodium citrate can be an environmentally friendly alternative to boric acid. In this research, nanocrystalline Ni deposits with different grain sizes were electrodeposited from citrate bath. The effects of sodium citrate concentration, current density and pH on the electrodeposited Ni properties were analyzed. The cathodic current efficiency decreased with the increase of sodium citrate due to the complexation of Ni2+ and citrate ions. Sodium citrate influenced the orientation and grain size of nickel deposits. The corrosion resistance of nickel deposits from citrate baths is comparable to that of b...
Proceedings of the 1st International Conference on Advances in Organic and Hybrid Electronic Materials
Materials Science and Engineering: A
Nanotechnology, Jan 11, 2016
SiO2-Ag-SiO2, a sandwiched core/shell structure with a layer of Ag nanoparticles (∼4 nm) encapsul... more SiO2-Ag-SiO2, a sandwiched core/shell structure with a layer of Ag nanoparticles (∼4 nm) encapsulated between a shallow SiO2 surface layer and a SiO2 submicrosphere substrate (∼200 nm), has been synthesized from [Formula: see text] and SiO2 spheres by a facile one-pot hydrothermal method. The composite is proposed to result from the dynamic balance between the [Formula: see text] reduction and the dissolution-redeposition of SiO2 in mild basic media. The synthetic mechanism and the roles of the reaction time, temperature, and the amount of ammonia in the formation of this unique structure are investigated and discussed. The composite structure shows superior catalytic performance in CO oxidation to the control Ag/SiO2 structure prepared by impregnation. Pre-treatment by O2 at 600 °C significantly improves the catalytic performance of the composite structure and preserves the nanocomposite structure well.
Nanotechnology, Jan 11, 2016
SiO2-Ag-SiO2, a sandwiched core/shell structure with a layer of Ag nanoparticles (∼4 nm) encapsul... more SiO2-Ag-SiO2, a sandwiched core/shell structure with a layer of Ag nanoparticles (∼4 nm) encapsulated between a shallow SiO2 surface layer and a SiO2 submicrosphere substrate (∼200 nm), has been synthesized from [Formula: see text] and SiO2 spheres by a facile one-pot hydrothermal method. The composite is proposed to result from the dynamic balance between the [Formula: see text] reduction and the dissolution-redeposition of SiO2 in mild basic media. The synthetic mechanism and the roles of the reaction time, temperature, and the amount of ammonia in the formation of this unique structure are investigated and discussed. The composite structure shows superior catalytic performance in CO oxidation to the control Ag/SiO2 structure prepared by impregnation. Pre-treatment by O2 at 600 °C significantly improves the catalytic performance of the composite structure and preserves the nanocomposite structure well.
Nanotechnology, Jan 11, 2016
SiO2-Ag-SiO2, a sandwiched core/shell structure with a layer of Ag nanoparticles (∼4 nm) encapsul... more SiO2-Ag-SiO2, a sandwiched core/shell structure with a layer of Ag nanoparticles (∼4 nm) encapsulated between a shallow SiO2 surface layer and a SiO2 submicrosphere substrate (∼200 nm), has been synthesized from [Formula: see text] and SiO2 spheres by a facile one-pot hydrothermal method. The composite is proposed to result from the dynamic balance between the [Formula: see text] reduction and the dissolution-redeposition of SiO2 in mild basic media. The synthetic mechanism and the roles of the reaction time, temperature, and the amount of ammonia in the formation of this unique structure are investigated and discussed. The composite structure shows superior catalytic performance in CO oxidation to the control Ag/SiO2 structure prepared by impregnation. Pre-treatment by O2 at 600 °C significantly improves the catalytic performance of the composite structure and preserves the nanocomposite structure well.