Browsing by Author "Zhou, Linan"
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Item Hot-carrier-mediated Chemical Processes in Plasmonic Photocatalysis(2019-04-09) Zhou, Linan; Halas, Naomi JPlasmonic nanomaterials, featured with high optical cross-section resulted from the induction of the collective oscillation of free electrons in metallic nanostructures, known as localized surface plasmon resonance, by the alternative electromagnetic wave in light, is emerging as a new promising photocatalyst. Hot carriers derived from the non-radiative decay of LSPR are capable in activating chemical bond, in an intrinsically different mechanism from the conventional thermal-driven means, and provide the possibility in achieving chemical transformation in milder conditions with sustainable energy. When further combined with catalytically active materials in a synergic way to form the antenna-reactor complexes, the versatility and efficiency of plasmonic photocatalysts are greatly boosted. In this thesis, I will present four plasmonic photocatalysts, classified into two categories, for three reactions to show the stepwise understanding of the structure-property-function relationship in plasmonic photocatalysts and subsequent improvement in the design of photocatalysts. The first part, including chapters 3 and 4, involves applying monometallic plasmonic nanomaterials in H2 activation. Au and Al nanomaterials, though being inert towards H2 activation if driven thermally, are demonstrated to be active in hydrogen dissociation under light excitation. They both exhibit linear intensity dependence in photocatalytic H2-D2 exchange reaction and H-H bond activated by the electronic transition of initial hot carriers is proposed to be the dominated mechanism. In contrast, Cu nanoparticles exhibit an S-shape intensity dependence in photocatalytic H2-D2 exchange reaction with a more-than-1 external quantum yield of light-to-chemical conversion. The hot carrier multiplication resulted from thermalization of hot carriers through electron-electron scattering plays a crucial role in the Cu system. The rate-determining step (RDS) is believed to be associative desorption of HD, different from the dissociative adsorption of H2/D2 on Au and Al surface, making the transition barrier of hot carriers low and the thermalized hot carriers effective. Next, I designed a new antenna-reactor structure, surface alloy, to incorporate materials with the favorable electronic structure for activation of specific molecules into plasmonic nanomaterials with intent to achieve better usage of hot carriers. Cu-Ru surface alloy was prepared and shows highly efficient photocatalytic activity towards ammonia decomposition reaction, making it feasible for studying the effect of plasmon-mediated hot carriers on the activation barrier of chemical reactions. By carefully tuning the loading ratio of Cu and Ru, I further synthesized single-atom-alloy plasmonic photocatalyst composed of a Cu core antenna with atomically dispersed Ru sites reactor on the surface. This antenna-reactor complex exhibits outstanding coke resistance in methane dry reforming reaction under illumination. Both of the hot carriers and single-atom structure were demonstrated to be essential for the observed stability. This thesis increases the knowledge in the mechanism of hot-carrier-mediated chemical reaction and guides the design of new generation of plasmonic photocatalysts.Item Metal-organic frameworks tailor the properties of aluminum nanocrystals(AAAS, 2019) Robatjazi, Hossein; Weinberg, Daniel; Swearer, Dayne F.; Jacobson, Christian; Zhang, Ming; Tian, Shu; Zhou, Linan; Nordlander, Peter; Halas, Naomi J.Metal-organic frameworks (MOFs) and metal nanoparticles are two classes of materials that have received considerable recent attention, each for controlling chemical reactivities, albeit in very different ways. Here, we report the growth of MOF shell layers surrounding aluminum nanocrystals (Al NCs), an Earth-abundant metal with energetic, plasmonic, and photocatalytic properties. The MOF shell growth proceeds by means of dissolution-and-growth chemistry that uses the intrinsic surface oxide of the NC to obtain the Al3+ ions accommodated into the MOF nodes. Changes in the Al NC plasmon resonance provide an intrinsic optical probe of its dissolution and growth kinetics. This same chemistry enables a highly controlled oxidation of the Al NCs, providing a precise method for reducing NC size in a shape-preserving manner. The MOF shell encapsulation of the Al NCs results in increased efficiencies for plasmon-enhanced photocatalysis, which is observed for the hydrogen-deuterium exchange and reverse water-gas shift reactions.Item Multicomponent plasmonic photocatalysts consisting of a plasmonic antenna and a reactive catalytic surface: the antenna-reactor effect(2020-09-08) Halas, Nancy Jean; Nordlander, Peter; Robatjazi, Hossein; Swearer, Dayne Francis; Zhang, Chao; Zhao, Hangqi; Zhou, Linan; Rice University; United States Patent and Trademark OfficeA multicomponent photocatalyst includes a reactive component optically, electronically, or thermally coupled to a plasmonic material. A method of performing a catalytic reaction includes loading a multicomponent photocatalyst including a reactive component optically, electronically, or thermally coupled to a plasmonic material into a reaction chamber, introducing molecular reactants into the reaction chamber, and illuminating the reaction chamber with a light source.Item Multicomponent plasmonic photocatalysts consisting of a plasmonic antenna and a reactive catalytic surface: the antenna-reactor effect(2024-04-16) Halas, Nancy Jean; Nordlander, Peter; Robatjazi, Hossein; Swearer, Dayne Francis; Zhang, Chao; Zhao, Hangqi; Zhou, Linan; Rice University; United States Patent and Trademark OfficeA method of making a multicomponent photocatalyst, includes inducing precipitation from a pre-cursor solution comprising a pre-cursor of a plasmonic material and a pre-cursor of a reactive component to form co-precipitated particles; collecting the co-precipitated particles; and annealing the co-precipitated particles to form the multicomponent photocatalyst comprising a reactive component optically, thermally, or electronically coupled to a plasmonic material.Item Multicomponent plasmonic photocatalysts consisting of a plasmonic antenna and a reactive catalytic surface: the antenna-reactor effect(2024-10-08) Halas, Nancy Jean; Nordlander, Peter; Robatjazi, Hossein; Swearer, Dayne Francis; Zhang, Chao; Zhao, Hangqi; Zhou, Linan; Rice University; United States Patent and Trademark OfficeA multicomponent photocatalyst includes a reactive component optically, electronically, or thermally coupled to a plasmonic material. A method of performing a catalytic reaction includes loading a multicomponent photocatalyst including a reactive component optically, electronically, or thermally coupled to a plasmonic material into a reaction chamber; introducing molecular reactants into the reaction chamber; and illuminating the reaction chamber with a light source.Item Plasmonic Photocatalysis of Nitrous Oxide into N2 and O2 Using Aluminum–Iridium Antenna–Reactor Nanoparticles(American Chemical Society, 2019) Swearer, Dayne F.; Robatjazi, Hossein; Martirez, John Mark P.; Zhang, Ming; Zhou, Linan; Carter, Emily A.; Nordlander, Peter; Halas, Naomi J.; Laboratory for NanophotonicsPhotocatalysis with optically active “plasmonic” nanoparticles is a growing field in heterogeneous catalysis, with the potential for substantially increasing efficiencies and selectivities of chemical reactions. Here, the decomposition of nitrous oxide (N2O), a potent anthropogenic greenhouse gas, on illuminated aluminum–iridium (Al–Ir) antenna–reactor plasmonic photocatalysts is reported. Under resonant illumination conditions, N2 and O2 are the only observable decomposition products, avoiding the problematic generation of NOx species observed using other approaches. Because no appreciable change to the apparent activation energy was observed under illumination, the primary reaction enhancement mechanism for Al–Ir is likely due to photothermal heating rather than plasmon-induced hot-carrier contributions. This light-based approach can induce autocatalysis for rapid N2O conversion, a process with highly promising potential for applications in N2O abatement technologies, satellite propulsion, or emergency life-support systems in space stations and submarines.