Direct Bottom-Up In Situ Growth: A Paradigm Shift for Studies in Wet-Chemical Synthesis of Gold Nanoparticles

Plasmonic gold nanoparticles have been used increasinglyin solid-statesystems because of their applicability in fabricating novel sensors,heterogeneous catalysts, metamaterials, and thermoplasmonic substrates.While bottom-up colloidal syntheses take advantage of the chemicalenvironment to control size, shape, composition, surface chemistry,and crystallography of the nanostructures precisely, it can be challengingto assemble nanoparticles rationally from suspension onto solid supportsor within devices. In this Review, we discuss a powerful recent syntheticmethodology, bottom-up in situ substrate growth,which circumvents time-consuming batch presynthesis, ligand exchange,and self-assembly steps by applying wet-chemical synthesis to formmorphologically controlled nanostructures on supporting materials.First, we briefly introduce the properties of plasmonic nanostructures.Then we comprehensively summarize recent work that adds to the syntheticunderstanding of in situ geometrical and spatialcontrol (patterning). Next, we briefly discuss applications of plasmonichybrid materials prepared by in situ growth. Overall,despite the vast potential advantages of in situ growth,the mechanistic understanding of these methodologies remains far fromestablished, providing opportunities and challenges for future research.