Earth-abundant photocatalyst for H ₂ generation from NH ₃ with light-emitting diode illumination

Abstract

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.

Active Site Engineering on Plasmonic Nanostructures for Efficient Photocatalysis

“…In other words, N 2 desorption is promoted by light (Cu plasmon)-assisted excitation of the adsorbate state (Ru–N). More recently, the same group further reported a plasmonic Cu-Fe-AR complex by replacing the Ru active site in Cu-Ru-AR with Fe . Interestingly, the Cu-Fe-AR, which is almost unreactive for thermocatalytic NH 3 decomposition, displayed similar photocatalytic activity with the Cu-Ru-AR.…”

“…The obtained product was used as the catalyst for Cu plasmon-driven NH 3 decomposition after being activated by sequential high-temperature treatment in He and H 2 . A similar method has also been used to prepare MgO-Al 2 O 3 -supported Cu-Fe antenna-reactor catalysts . This coprecipitation method is facile to operate and allows mass catalyst production.…”

“…Second, a molecule-level understanding of the catalytic process is essential for guiding the rational design of high-performance plasmonic photocatalysts. The catalytic process for reactant conversion involves a sequence of events, including reactant adsorption, intermediate formation, and product desorption, all of which have significant impacts on catalytic performance . For instance, the chemisorption of reactants on catalyst surfaces promotes the formation of adsorbate states, allowing efficient energy coupling between LSPR and surface reactions .…”

“…A similar method has also been used to prepare MgO-Al 2 O 3 -supported Cu-Fe antenna-reactor catalysts. 33 This coprecipitation method is facile to operate and allows mass catalyst production. However, vigorous stir and careful pH control are needed during the synthetic process to ensure the simultaneous precipitation and homogeneous distribution of the multicomponents.…”

“…Among the various candidates, plasmonic photocatalysts have been extensively studied due to their tunable absorption in the visible and near-infrared (NIR) light range. − In the early stage, plasmonic photocatalysts were generally fabricated by combining plasmonic metal nanostructures with wide bandgap semiconductors, where plasmonic metals functioned as the photosensitizer to enhance the surface reaction on semiconductors. , Beyond that, the direct interaction between plasmonic metals with their surface-adsorbed molecules was also observed under laser irradiation. − In 2011, Linic and co-workers reported the direct molecular oxygen activation and ethylene epoxidation on plasmonic Ag nanocubes (∼60 nm), , which in turn accelerated the development of plasmonic photocatalysis. − With continual research interest, the interaction between plasmonic metal and its surface molecules or adjacent semiconductors has been intensively investigated . Furthermore, the importance of active site engineering on plasmonic nanostructures has gradually gained traction. , In brief, traditional plasmonic metals, such as Cu, Ag, and Au, typically exhibit weak interactions with reactants or reaction intermediates (i.e., low intrinsic activities) due to their fully filled d bands .…”