Electrochemical and optical band gaps of bimetallic silver-platinum varying metal ratios nanoparticles

Simultaneous citrate reduction of various ratios of silver and platinum ions leads to the formation of core-shell nanostructured bimetallics (BM). Transmission electron microscopy (TEM) and X-ray diffraction XRD data of the BMs depicted crystalline core-shell nanoparticles consisting of Ag core and Pt shell with an average size of 22.2 nm in contrast to the  Pt NPs and Ag NPs monometallics  average sizes of 2.5 and 60.0 nm respectively. Tauc’s calculated optical band gaps ranged from 3.55 to 4.02 eV while the electrochemical based on Breda’s equation had a range of 1.45 to 1.80 eV. These band gaps range variation maybe due to inter atomic interaction, morphology and quantum confinement. Generally, bimetallics had higher band gaps relative to monometallics. The Ag: Pt ratio of 3:1 had the highest optical band gap and the smallest particle size. While the ratio of 1:3 had the highest electrochemical band gap as well as the largest particle size among the BMs. Suggesting band gap dependence on amount of Ag and Pt for optical and electrochemical respectively. Key words: Optical, electrochemical, band gaps, bimetallic, nanoparticles.