PHOTOVOLTAIC HYDROGEN PRODUCTION PROTOTYPE:SUSTAINABLE ENERGY FOR RESIDENCES

Residential use of hydrogen(H_(2)),for utility or personal transportation,is currently limited by economic effectiveness,lack of residential sources,and need for engineering improvements.A modular photovoltaic hydrogen production prototype(PHPP)was constructed to produce three liters of hydrogen per day at standard temperature and pressure with maximum energy and Faraday efficiencies of 75%and 89%,respectively.Producing 3 liters of H_(2)with the PHPP required 2.4 milliliters of distilled H_(2)O and 26 kJ of solar energy and eliminated 1.5 liters of byproduct CO_(2)relative to steam reforming of methane to generate H_(2).A capital investment of$5,651 to produce 30 liters per day using additional PHPP modules gave a return on investment of 4.2%and a payback period of 7.5 years.Interdisciplinary teams of university and high school students constructed the PHPP and were familiarized with key aspects of sustainable use of hydrogen as an energy carrier.Language and geographical barriers to effective communication and teamwork among the students were met by organizing teams to meet student needs,providing instruction and hands-on training in teamwork and facilitating web-based and in-class interactions.Quantitative ethnographic observation of student interactions showed involving students in lectures and extracurricular presentations and enhancing communication and teamwork with constructive responses to student feedback increased student satisfaction with the experience.

Attribution of Fano resonant features to plasmonic particle size, lattice constant, and dielectric wavenumber in square nanoparticle lattices

Fano resonances between plasmons and diffracted light offer tunable energies and locales,but attribution of Fano resonance features to geometry and physicochemistry of metal nanostructures and adjacent dielectrics has been confounded by complexity and computational expense.This work shows predictable modal shifts of Fano resonance in square lattices of plasmonic nanostructures can be attributed directly to changes in medium wavenumber,particle size,and lattice constant that alter plasmon polarizability and diffractive interference.For 45 to 80 nm radius particles,a window of lattice constants that support Fano resonances is identified in a range from 500 to 900 nm.Lattice constants that support high intensity resonances are determined by individual particle polarizability and medium wavenumber.Fano resonance wavelengths redshift from diffracted photon energies as local refractive index(RI)changes due to coupling with particle polarizability in the window.Redshift sensitivities for quadrupole,dipole,and Fano resonances are 150,348,and 541 nm,respectively,per RI unit.Fano resonance intensity may be enhanced more than tenfold by selecting nanoparticle sizes and lattice constants.The quantitative effects of such parametric changes are rapidly and intuitively distinguished using a semi-analytic approach,consisting of an exact expression for particle polarizability,a trigonometric description of diffraction,and a semianalytical coupled dipole approximation.