Ligand-free fabrication of Au/TiO2 nanostructures for plasmonic hot-electron-driven photocatalysis: Photoelectrochemical water splitting and organic-dye degredation

Abstract

Herein, an alternative/cost-effective simple synthesis route was accurately designed to fabricate ligand-free Au/TiO2 Schottky contacts. This time-saving technique provided one-step binding of pre-synthesized NaBH4 stabilized colloidal Au NPs thanks to oxygen vacancies on the rutile phase. The strong/close conjugation provided an ideal plasmon-sensitive heterostructures with desired SPR excited charge separation to explore a strategy for an enhanced photoelectrochemical (PEC) water splitting and organic-dye photodegradation. Toward the plasmonic hot-electron driven PEC water splitting, the highest photocurrent density was obtained as 1.87 mA/cm2 for Au2x/TiO2 at low potential 0.187 V vs RHE under visible-LED light illumination (30 mW/cm2) which is 6.6-fold higher than bare TiO2 (0.28 mA/cm2). This superior PEC performance was recorded with low amount of Au loading (0.154 wt%) and very low light intensity (visible-LED light illumination; 30 mW/cm2). Additionally, owing to the advantages of newly synthesized Au/TiO2 Schottky contacts, an enhanced photocatalytic activity was recorded with 97% decolorization of methylene blue (MB) during 150 min under visible LED light illumination. This novel fabrication strategy provided a next generation of visible light responsive heteronanostructures with no need for additional pre-fabrication procedures with potential large-scale PEC water splitting applications.