Photoenhanced Degradation of Sarin at Cu/TiO Composite Aerogels: Roles of Bandgap Excitation and Surface Plasmon Excitation.

Multifunctional composites that couple high-capacity adsorbents with catalytic nanoparticles (NPs) offer a promising route toward the degradation of organophosphorus pollutants or chemical warfare agents (CWAs). We couple mesoporous TiO aerogels with plasmonic Cu nanoparticles (Cu/TiO) and characterize the degradation of the organophosphorus CWA sarin under both dark and illuminated conditions. Cu/TiO aerogels combine high dark degradation rates, which are facilitated by hydrolytically active sites at the Cu||TiO interface, with photoenhanced degradation courtesy of semiconducting TiO and the surface plasmon resonance (SPR) of the Cu nanoparticles.

Stabilization of reduced copper on ceria aerogels for CO oxidation.

Photodeposition of Cu nanoparticles on ceria (CeO) aerogels generates a high surface area composite material with sufficient metallic Cu to exhibit an air-stable surface plasmon resonance. We show that balancing the surface area of the aerogel support with the Cu weight loading is a critical factor in retaining stable Cu. At higher Cu weight loadings or with a lower support surface area, Cu aggregation is observed by scanning and transmission electron microscopy.

Power of Aerogel Platforms to Explore Mesoscale Transport in Catalysis.

We describe the opportunity to deploy aerogels-an ultraporous nanoarchitecture with co-continuous networks of meso/macropores and covalently bonded nanoparticulates-as a platform to address the nature of the electronic, ionic, and mass transport that underlies catalytic activity. As a test case, we fabricated Au||TiO junctions in composite guest-host aerogels in which ∼5 nm Au nanoparticles are incorporated either directly into the anatase TiO network (Au "in" TiO, Au-TiO aerogel) or deposited onto preformed TiO aerogel (Au "on" TiO, Au/TiO aerogel). The metal-meets-oxide nanoscale interphase as visualized by electron tomography feature extended three-dimensional (3D) interfaces, but Au-TiO aerogels impose a greater degree of Au contact with TiO particles than does the Au/TiO form.

Oxidation-stable plasmonic copper nanoparticles in photocatalytic TiO nanoarchitectures.

Ultraporous copper/titanium dioxide (Cu/TiO) aerogels supporting <5 nm diameter copper nanoparticles are active for surface plasmon resonance (SPR)-driven photocatalysis. The extended nanoscale Cu‖TiO junctions in Cu/TiO composite aerogels-which arise as a result of photodepositing copper at the surface of the nanoparticulate-bonded TiO aerogel architecture-stabilize Cu against oxidation to an extent that preserves the plasmonic behavior of the nanoparticles, even after exposure to oxidizing conditions. The metallicity of the Cu nanoparticles within the TiO aerogel is verified by aberration-corrected scanning transmission electron microscopy, electron energy-loss spectroscopy, and infrared spectroscopy using CO binding as a probe to distinguish Cu(0) from Cu(i).

Plasmonic Aerogels as a Three-Dimensional Nanoscale Platform for Solar Fuel Photocatalysis.

We use plasmonic Au-TiO aerogels as a platform in which to marry synthetically thickened particle-particle junctions in TiO aerogel networks to Au∥TiO interfaces and then investigate their cooperative influence on photocatalytic hydrogen (H) generation under both broadband (i.e., UV + visible light) and visible-only excitation.

Graphitic biochar as a cathode electrocatalyst support for microbial fuel cells.

Graphitic biochar (BC) was generated using high temperature gasification and alkaline post-treatment (BCw) of wood-based biomass. The BCw was evaluated as a manganese oxide electrocatalytic support (MnO/BCw) and microbial fuel cell (MFC) air cathode. Nano-structured MnO2 crystals were successfully immobilized on biomass-based graphitic sheets and characterized using physical, chemical, and electrochemical analyses.

Plasmonic enhancement of visible-light water splitting with Au-TiO2 composite aerogels.

We demonstrate plasmonic enhancement of visible-light-driven splitting of water at three-dimensionally (3D) networked gold-titania (Au-TiO2) aerogels. The sol-gel-derived ultraporous composite nanoarchitecture, which contains 1 to 8.5 wt% Au nanoparticles and titania in the anatase form, retains the high surface area and mesoporosity of unmodified TiO2 aerogels and maintains stable dispersion of the ~5 nm Au guests.

The utility of Shewanella japonica for microbial fuel cells.

Shewanella-containing microbial fuel cells (MFCs) typically use the fresh water wild-type strain Shewanella oneidensis MR-1 due to its metabolic diversity and facultative oxidant tolerance. However, S. oneidensis MR-1 is not capable of metabolizing polysaccharides for extracellular electron transfer.

Measurement of benzenethiol adsorption to nanostructured Pt, Pd, and PtPd films using Raman spectroelectrochemistry.

Raman spectroscopy and electrochemical methods were used to study the behavior of the model adsorbate benzenethiol (BT) on nanostructured Pt, Pd, and PtPd electrodes as a function of applied potential. Benzenethiol adsorbs out of ethanolic solutions as the corresponding thiolate, and voltammetric stripping data reveal that BT is oxidatively removed from all of the nanostructured metals upon repeated oxidative and reductive cycling. Oxidative stripping potentials for BT increase in the order Pt < PtPd < Pd, indicating that BT adsorbs most strongly to nanoscale Pd.

Triarylphosphine-stabilized platinum nanoparticles in three-dimensional nanostructured films as active electrocatalysts.

Ligand-stabilized platinum nanoparticles (Pt NPs) can be used to build well-defined three-dimensional (3-D) nanostructured electrodes for better control of the catalyst architecture in proton exchange membrane fuel cells (PEMFCs). Platinum NPs of 1.7 +/- 0.

Using an oxide nanoarchitecture to make or break a proton wire.

We report that long-range proton diffusion (>0.3 mm) is generated in monolithic ultraporous manganese oxide nanoarchitectures upon exposure to gas-phase water. The sol-gel-derived ambigel nanoarchitectures, with bicontinuous networks of covalently bonded nanoscale solid and through-connected mesopores, exhibit conductometric sensitivity to humidity as established by impedance spectroscopy.

Gold nanoelectrodes of varied size: transition to molecule-like charging.

A transition from metal-like double-layer capacitive charging to redox-like charging was observed in electrochemical ensemble Coulomb staircase experiments on solutions of gold nanoparticles of varied core size. The monodisperse gold nanoparticles are stabilized by short-chain alkanethiolate monolayers and have 8 to 38 kilodaltons core mass (1.1 to 1.