Catalysts based on platinum group metals have been a major focus of the chemical industry for decades. We show that plasmonic photocatalysis can transform a thermally unreactive, earth-abundant transition metal into a catalytically active site under illumination. Fe active sites in a Cu-Fe antenna-reactor complex achieve efficiencies very similar to Ru for the photocatalytic decomposition of ammonia under ultrafast pulsed illumination. When illuminated with light-emitting diodes rather than lasers, the photocatalytic efficiencies remain comparable, even when the scale of reaction increases by nearly three orders of magnitude. This result demonstrates the potential for highly efficient, electrically driven production of hydrogen from an ammonia carrier with earth-abundant transition metals.
Plasmonic metal nanostructures have garnered rapidly increasing interest as heterogeneous photocatalysts, facilitating chemical bond activation and overcoming the high energy demands of conventional thermal catalysis. Here we report the highly efficient plasmonic photocatalysis of the direct decomposition of hydrogen sulfide into hydrogen and sulfur, an alternative to the industrial Claus process. Under visible light illumination and with no external heat source, up to a 20-fold reactivity enhancement compared to thermocatalysis can be observed. The substantially enhanced reactivity can be attributed to plasmon-mediated hot carriers (HCs) that modify the reaction energetics. With a shift in the rate-determining step of the reaction, a new reaction pathway is made possible with a lower apparent reaction barrier. Light-driven one-step decomposition of hydrogen sulfide represents an exciting opportunity for simultaneous high-efficiency hydrogen production and low-temperature sulfur recovery, important in many industrial processes.
Plasmon-induced photocatalysis is
a topic of rapidly increasing
interest, due to its potential for substantially lowering reaction
barriers and temperatures and for increasing the selectivity of chemical
reactions. Of particular interest for plasmonic photocatalysis are
antenna–reactor nanoparticles and nanostructures, which combine
the strong light-coupling of plasmonic nanostructures with reactors
that enhance chemical specificity. Here, we introduce Al@TiO2 core–shell nanoparticles, combining earth-abundant Al nanocrystalline
cores with TiO2 layers of tunable thickness. We show that
these nanoparticles are active photocatalysts for the hot electron-mediated
H2 dissociation reaction as well as for hot hole-mediated
methanol dehydration. The wavelength dependence of the reaction rates
suggests that the photocatalytic mechanism is plasmonic hot carrier
generation with subsequent transfer of the hot carriers into the TiO2 layer. The Al@TiO2 antenna–reactor provides
an earth-abundant solution for the future design of visible-light-driven
plasmonic photocatalysts.
The field of plasmonics has largely been inspired by the properties of Au and Ag nanoparticles, leading to applications in sensing, photocatalysis, nanomedicine, and solar water treatment. Recently the quest for new plasmonic materials has focused on earth-abundant elements, where aluminum is a sustainable, low-cost potential alternative. Here we report the chemical synthesis of sub-50 nm diameter Al nanocrystals with a plasmon-resonant absorption in the UV region of the spectrum. We observe a transition from a UV-resonant response, that is, a colorless solution, to a broadband absorptive response, that is, a completely black solution, as the nanocrystal concentration is increased. The strong absorptive interband transition in Al provides the dominant mechanism responsible for this effect. We developed a robust method to functionalize Al nanocrystals with silica to increase their stability in H 2 O from hours to weeks enabling us to observe efficient broadband photothermal heating with these nanoparticles.
Herein we provide direct experimental evidence that proves that the photophysical properties of thin methylammonium lead iodide perovskite films are significantly enhanced by localized surface plasmon resonances (SPRs).
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