Materials for solid base catalysts and oxygen storage

Ph.DDOCTOR OF PHILOSOPH

Multiple Ambient Hydrolysis Deposition of Tin Oxide into Nanoporous Carbon as a Stable Anode for Lithium-Ion Batteries

We introduce a novel ambient hydrolysis deposition (AHD) methodology that, for the first time, employs sequential water adsorption followed by a hydrolysis reaction to infiltrate tiny SnO2₂ particles inside nanopores of mesoporous carbon in a conformal and controllable manner. The empty space in the SnO2₂/C composites can be adjusted by varying the number of AHD cycles. A SnO2₂/C composite with an intermediate SnO2₂ loading exhibits an initial specific delithiation capacity of 1054 mAh/g as an anode for Li-ion batteries (LIBs). The capacity contribution from SnO2₂ in the composite electrode of SnO2₂ (1494 mAh/g) when considering that both Sn alloying and SnO2₂ conversion reactions are reversible. The composite shows a specific capacity of 573 mAh/g after 300 cycles, one of the most stable cycling performances for the SnO2₂/mesoporous carbon composites. Enabled by the controllable AHD coatings, our results demonstrated the importance of the well-tuned empty space in nanostructured composites to accommodate the expansion of electrode active mass during alloying/dealloying and conversion reactions.Keywords: Sequential, Mesoporous materials, Tin, Lithium-ion batteries, Nanoparticles, SnO2₂/C composite, Electrochemistry, Hydrolysis depositio

Ambient Hydrolysis Deposition of TiO₂ in Nanoporous Carbon and the Converted TiN/Carbon Capacitive Electrode

Despite the considerable advances of deposition technologies, it remains a significant challenge to form conformal deposition on surface of nanoporous carbons. Here, we introduce a new ambient hydrolysis deposition method that employs and controls pre-adsorbed water vapor on nanoporous carbons to define the deposition of TiO₂. We converted the deposited TiO₂ into TiN via a nitridation process. The metallic-TiN-coated porous carbon exhibits superior kinetic performance as an electrode in electrical double layer capacitors. The novel deposition method provides a general solution for surface engineering on nanostructured carbons, which may result in a strong impact on the fields of energy storage and other disciplines

Superior Cathode of Sodium-Ion Batteries: Orthorhombic V₂O₅ Nanoparticles Generated in Nanoporous Carbon by Ambient Hydrolysis Deposition

We, for the first time, demonstrate that orthorhombic V₂O₅ can exhibit superior electrochemical performance in sodium ion batteries when uniformly coated inside nanoporous carbon. The encapsulated V₂O₅ shows a specific capacity as high as 276 mAh/g, while the whole nanocomposite exhibits a capacity of 170 mAh/g. The V₂O₅/C composite was fabricated by a novel ambient hydrolysis deposition that features sequential water vapor adsorption in nanoporous carbon, followed by a hydrolysis reaction, exclusively inside the nanopores. The unique structure of the nanocomposite significantly enhances the capacity as well as the rate performance of orthorhombic V₂O₅ where the composite retains a capacity of over 90 mAh/g at a current rate of 640 mA/g. Furthermore, by calculating, we also revealed that a large portion of the sodium-ion storage, particularly at high current rates, is due to the V₂O₅ pseudocapacitance.Keywords: Pseudocapacitance, Sodium-Ion Batteries, Orthorhombic V₂O₅, Ambient Hydrolysis Depositio

Molecular Storage of Mg Ions with Vanadium Oxide Nanoclusters

Mg batteries have potential advantages in terms of safety, cost, and reliability over existing battery technologies, but their practical implementations are hindered by the lack of amenable high-voltage cathode materials. The development of cathode materials is complicated by limited understandings of the unique divalent Mg²⁺ ion electrochemistry and the interaction/transportation of Mg²⁺ ions with host materials. Here, it is shown that highly dispersed vanadium oxide (V₂O₅) nanoclusters supported on porous carbon frameworks are able to react with Mg²⁺ ions reversibly in electrolytes that are compatible with Mg metal, and exhibit high capacities and good reaction kinetics. They are able to deliver initial capacities exceeding 300 mAh g⁻¹ at 40 mA g⁻¹ in the voltage window of 0.5 to 2.8 V. The combined electron microscope, spectroscopy, and electrochemistry characterizations suggest a surface-controlled pseudocapacitive electrochemical reaction, and may be best described as a molecular energy storage mechanism. This work can provide a new approach of using the molecular mechanism for pseudocapacitive storage of Mg²⁺ for Mg batteries cathode materials

Ji[David]XiuleiChemistryAmbientHydrolysisDeposition.pdf

Despite the considerable advances of deposition technologies, it remains a significant challenge to form conformal deposition on surface of nanoporous carbons. Here, we introduce a new ambient hydrolysis deposition method that employs and controls pre-adsorbed water vapor on nanoporous carbons to define the deposition of TiO₂. We converted the deposited TiO₂ into TiN via a nitridation process. The metallic-TiN-coated porous carbon exhibits superior kinetic performance as an electrode in electrical double layer capacitors. The novel deposition method provides a general solution for surface engineering on nanostructured carbons, which may result in a strong impact on the fields of energy storage and other disciplines

Ji[David]XiuleiChemistryAmbientHydrolysisDeposition(SupportingInformation).pdf

Despite the considerable advances of deposition technologies, it remains a significant challenge to form conformal deposition on surface of nanoporous carbons. Here, we introduce a new ambient hydrolysis deposition method that employs and controls pre-adsorbed water vapor on nanoporous carbons to define the deposition of TiO₂. We converted the deposited TiO₂ into TiN via a nitridation process. The metallic-TiN-coated porous carbon exhibits superior kinetic performance as an electrode in electrical double layer capacitors. The novel deposition method provides a general solution for surface engineering on nanostructured carbons, which may result in a strong impact on the fields of energy storage and other disciplines

Superior cathode of sodium-ion batteries: orthorhombic V₂O₅ nanoparticles generated in nanoporous carbon by ambient hydrolysis deposition.

For the first time, we demonstrate that orthorhombic V2O5 can exhibit superior electrochemical performance in sodium ion batteries when uniformly coated inside nanoporous carbon. The encapsulated V2O5 shows a specific capacity as high as 276 mAh/g, while the whole nanocomposite exhibits a capacity of 170 mAh/g. The V2O5/C composite was fabricated by a novel ambient hydrolysis deposition that features sequential water vapor adsorption in nanoporous carbon, followed by a hydrolysis reaction, exclusively inside the nanopores. The unique structure of the nanocomposite significantly enhances the capacity as well as the rate performance of orthorhombic V2O5 where the composite retains a capacity of over 90 mAh/g at a current rate of 640 mA/g. Furthermore, by calculating, we also revealed that a large portion of the sodium-ion storage, particularly at high current rates, is due to the V2O5 pseudocapacitance

Ji[David]XiuleiChemistrySuperiorCathodeSodium.pdf

We, for the first time, demonstrate that orthorhombic V₂O₅ can exhibit superior electrochemical performance in sodium ion batteries when uniformly coated inside nanoporous carbon. The encapsulated V₂O₅ shows a specific capacity as high as 276 mAh/g, while the whole nanocomposite exhibits a capacity of 170 mAh/g. The V₂O₅/C composite was fabricated by a novel ambient hydrolysis deposition that features sequential water vapor adsorption in nanoporous carbon, followed by a hydrolysis reaction, exclusively inside the nanopores. The unique structure of the nanocomposite significantly enhances the capacity as well as the rate performance of orthorhombic V₂O₅ where the composite retains a capacity of over 90 mAh/g at a current rate of 640 mA/g. Furthermore, by calculating, we also revealed that a large portion of the sodium-ion storage, particularly at high current rates, is due to the V₂O₅ pseudocapacitance.Keywords: Sodium-Ion Batteries, Orthorhombic V₂O₅, Pseudocapacitance, Ambient Hydrolysis DepositionKeywords: Sodium-Ion Batteries, Orthorhombic V₂O₅, Pseudocapacitance, Ambient Hydrolysis Depositio