Controlling Selectivity in Plasmonic Catalysis: Switching Reaction Pathway from Hydrogenation to Homocoupling Under Visible-Light Irradiation

Plasmonic catalysis enables the use of light to accelerate molecular transformations. Its application to the control reaction selectivity is highly attractive but remains challenging. Here, we have found that the plasmonic properties in AgPd nanoparticles allowed different reaction pathways for tunable product formation under visible-light irradiation. By employing the hydrogenation of phenylacetylene as a model transformation, we demonstrate that visible-light irradiation can be employed to steer the reaction pathway from hydrogenation to homocoupling. Our data showed that the decrease in the concentration of H species at the surface due to plasmon-enhanced H2 desorption led to the control in selectivity. These results provide important insights into the understanding of reaction selectivity with light, paving the way for the application of plasmonic catalysis to the synthesis of 1,3-diynes, and bringing the vision of light-driven transformations with target selectivity one step closer to reality.</p

How a Nanostructure’s Shape Affects its Lifetime in the Environment: Comparing a Silver Nanocube to a Nanoparticle When Dispersed in Aqueous Media

Herein, we detail how the morphology of a nanomaterial affects its environmental lifetime in aquatic ecosystems. In particular, we focus on the cube and particle nanostructures of Ag and age them in various aquatic mediums including synthetic hard water, pond water, and seawater. Our results show that in the synthetic hard water and pond water cases, there was little difference in the rate of morphological changes as determined by UV–vis spectroscopy. However, when these samples were analyzed with transmission electron microscopy, radically different mechanisms in the loss of their original nanostructures were observed. Specifically, for the nanocube we observed that the corners of the cubes had become more rounded, whereas the aged nanoparticles formed large aggregates. Most interestingly, when the seawater samples were analyzed, the nanocubes showed a substantially higher stability in maintaining the nano length scale in comparison to nanoparticles overtime. Moreover, high-resolution transmission electron microscopy analysis allowed us to determine that Ag+ ions diffused away from both the edge and from the faces of the cube, whereas the nanoparticle rapidly aggregated under the harsh seawater conditions