Balancing near-field enhancement and hot carrier injection: plasmonic photocatalysis in energy-transfer cascade assemblies

Abstract

Photocatalysisstands as a very promisingalternativeto photovoltaicsin exploitingsolar energyand storingit inchemicalproductsthrougha single-stepprocess.A centralobstacleto its broad implementationis its low conversionefficiency,motivatingresearchin differentfields to bring about a breakthroughin this technology.Using plasmonicmaterialsto photosensitizetraditionalsemiconductorphotocatalystsis a popularstrategywhose full potentialis yet to be fully exploited.In this work, we useCdS quantumdots as a bridge system,reapingenergyfrom Au nanostructuresand deliveringit to TiO2nanoparticlesservingascatalyticcenters.The quantumdots can do this by becomingan intermediatestep in a charge-transfercascadeinitiatedin theplasmonicsystemor by creatingan electron−holepair at an improvedrate due to their interactionwith the enhancednear-fieldcreatedby the plasmonicnanoparticles.Our results show a significantaccelerationin the reactionupon combiningthese elementsinhybrid colloidalphotocatalyststhat promotethe role of the near-fieldenhancementeffect, and we show how to engineercomplexesexploitingthis approach.In doing so, we also explorethe complexinterplaybetweenthe differentmechanismsinvolvedin thephotocatalyticprocess,highlightingthe importanceof the Au nanoparticles’morphologyin their photosensitizingcapabilities