Plasmonic Ag nanoparticles decorated Bi2S3 nanorods and nanoflowers: Their comparative assessment for photoelectrochemical water splitting

In the present work, nanostructures comprising of plasmonic silver (Ag) nanoparticles (NPs) decorated on the hydrothermally grown bismuth sulfide nanorods (Bi2S3–NR) and hierarchical nanoflowers (Bi2S3NF) have been successfully synthesized by chemical route. We have fabricated the nanostructured photoanodes and demonstrated their enhanced photoelectrochemical (PEC) performance for water splitting applications. Bismuth sulfide nanoflowers have shown appreciable increased PEC activity due to its hierarchical structure as compared to the nanorods facilitated by the faster charge transport due to the availability of more interfacial sites. Among all, Ag/Bi2S3NF photoanode has exhibited highest photocurrent density (12.34 mA/cm2 at 2 V vs. Ag/AgCl) which is ∼2 fold higher as compared to Bi2S3 nanoflowers. A ∼3 fold enhancement in the incident photon-to-current conversion efficiency is achieved by Ag/Bi2S3NF photoanode as compared to Bi2S3NF photoanode. The remarkable enhancement in the photocurrent density of Bi2S3 after grafting metal plasmons is attributed to its enhanced photoresponse, faster transfer of plasmon mediated hot electrons from excited state of Ag NPs to Bi2S3 surface and higher separation efficiency of photogenerated charge carriers facilitated by the metal-semiconductor interface. A plausible mechanism is also proposed for the improved PEC water splitting over Ag/Bi2S3NF photoanode.