State of the art electrocatalysts for the hydrogen evolution reaction (HER) are based on metal nanoparticles (NPs). It has been shown that the localized surface plasmon resonance (LSPR) excitation in plasmonic NPs can be harvested to accelerate a variety of molecular transformations. This enables the utilization of visible light as an energy input to enhance HER performances. However, most metals that are active toward the HER do not support LSPR excitation in the visible or near-IR ranges. We describe herein the synthesis of gold−rhodium core− shell nanoflowers (Au@Rh NFs) that are composed of a core made up of spherical Au NPs and shells containing Rh branches. The Au@Rh NFs were employed as a model system to probe how the LSPR excitation from Au NPs can lead to an enhancement in the HER performance for Rh. Our data demonstrate that the LSPR excitation at 533 nm (and 405 nm) leads to an improvement in the HER performance of Rh, which depends on the morphological features of the Au@Rh NFs, offering opportunities for optimization of the catalytic performance. Control experiments indicate that this improvement originates from the stronger interaction of Au@Rh NFs with H 2 O molecules at the surface, leading to an icelike configuration, which facilitated the HER under LSPR excitation.

Localized surface plasmon resonance (LSPR) is a phenomenon derived from the interaction between light and nanostructures, and its outcomes have been explored mainly for applications in surface-enhanced Raman spectroscopy (SERS), phototherapy, and catalysis. Bimetallic nanostructures are able to synergically combine the properties of two different metals to create a tuned response to LSPR according to their composition, shape, and morphology. In this study, an in situ synthesis of AgAu bimetallic hollow nanoshells (NS) over layered graphene oxide (GO) and silica submicrospheres (SiO 2 ) is presented. The synthesized structures acted as peroxidase-like nanozymes in the plasmon-enhanced electrochemical sensing of H 2 O 2 . The nanozymes were submitted to 405, 533, and 650 nm laser irradiation while performing the hydrogen peroxide reduction reaction (HPRR) with a fast response speed (4 s), exhibiting enhancements in sensitivity of 122% (for Ag 79 Au 21 /GO at 533 nm, 787 μA mM −1 cm −2 ), 105% (for Ag 79 Au 21 /GO at 405 nm, 725 μA mM −1 cm −2 ), and 119% (for Ag 50 Au 50 /SiO 2 at 650 nm, 885 μA mM −1 cm −2 ) compared to the dark conditions when matching the LSPR band maximum for each synthesized structure. When laser stimuli did not match LSPR band maximum, lower enhancements were achieved in both cases. According to Michaelis−Menten enzyme kinetics, the nanozymes I max followed the same LSPR bias and K m app was lowered after LSPR stimuli, showing the smallest values upon 405 nm irradiation (0.599 mM for Ag 79 Au 21 /GO and 0.228 mM for Ag 50 Au 50 /SiO 2 ) demonstrating increased substrate affinity in comparison to values previously reported in enzymatic and nonenzymatic biosensors of H 2 O 2 . Thus, we propose that LSPR is the main mechanism involved in the faster electron transfer rates and the consequent enhancement of electrochemical H 2 O 2 sensitivities, I max , and K m app by the bimetallic nanozymes synthesized by this approach.

The localized surface plasmon resonance (LSPR) excitation in plasmonic nanoparticles (NPs) in the visible and near-infrared ranges is currently at the forefront of improving photocatalytic performances via plasmonic photocatalysis. One bottleneck of this field is that the NPs that often display the best optical properties in the visible and near-infrared ranges are based on expensive noble metals such as silver (Ag) and gold (Au). While earth-abundant plasmonic materials have been proposed together with catalytic metals in antenna–reactor systems, their performances remain limited by their optical properties. Importantly, the synthesis of plasmonic photocatalysts remains challenging in terms of scalability while often requiring several steps, high temperatures, and special conditions. Herein, we address these challenges by developing a one-pot, gram-scale, room-temperature synthesis of earth-abundant plasmonic photocatalysts while improving their activities beyond what has been dictated by the LSPR excitation of the plasmonic component. We describe the mechanochemical synthesis of earth-abundant plasmonic photocatalysts by using MoO3 (antenna) and Au (reactor) NPs as a proof-of-concept example and demonstrate that the dual plasmonic excitation of antenna and reactor sites enables the tuning of plasmonic photocatalytic performances toward the reductive coupling of nitrobenzene to azobenzene as a model reaction. In addition to providing a pathway to the facile and gram-scale synthesis of plasmonic photocatalysts, the results reported herein may open pathways to improved activities in plasmonic catalysis.

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