On a high photocatalytic activity of high-noble alloys Au-Ag/TiO2 catalysts during oxygen evolution reaction of water oxidation.

ABSTRACT

The analysis via density functional theory was employed to understand high photocatalytic activity found on the Au-Ag high-noble alloys catalysts supported on rutile TiO2 during the oxygen evolution of water oxidation reaction (OER). It was indicated that the most thermodynamically stable location of the Au-Ag bimetal-support interface is the bridging row oxygen vacancy site. On the active region of the Au-Ag catalyst, the Au site is the most active for OER catalyzing the reaction with an overpotential of 0.60 V. Whereas the photocatalytic activity of other active sites follows the trend of Au > Ag > Ti. This finding evident from the projected density of states revealed the formation of the trap state that reduces the band gap of the catalyst promoting activity. In addition, the Bader charge analysis revealed the electron relocation from Ag to Au to be the reason behind the activity of the bimetallic that exceeds its monometallic counterparts.