In situ exsolution of silver nanoparticles on AgTaO3-SrTiO3 solid solutions as efficient plasmonic photocatalysts for water splitting

Abstract

Starting from two wide band gap semiconductors AgTaO3 and SrTiO3, we managed to reduce the band gap by forming their solid solutions, i.e. (AgTaO3)1-x(SrTiO3)x (0.0 ≤ x ≤ 1.0). These solid solutions all adopt cubic perovskite structure similar to SrTiO3 and high temperature phase of AgTaO3, suggesting that SrTiO3 is helpful to stabilize AgTaO3 in its high temperature cubic phase. Substantial improvements over photocatalytic hydrogen production were realized in these solid solutions which clearly outperform their parent compounds AgTaO3 and SrTiO3. In-situ exolution of silver nanoparticles at the surface of solid solutions (x = 0.2) substantially strengthen the visible light absorption due to localized surface plasmons of these silver nanoparticles. This contributes to further improvements on both photocatalytic hydrogen and oxygen production under visible light illumination (λ ≥ 400 nm). Apparent quantum efficiency as high as ˜ 2.02% and ˜ 0.11% was achieved at solid solutions (x = 0.2) decorated with silver nanoparticles for full range (λ ≥ 250 nm) and visible light (λ ≥ 400 nm) illumination respectively. Photoelectrochemical analysis suggests that solid solutions own a better charge separation conditions than their parent compounds. Furthermore, the band edge positions of solid solutions (x = 0.2) lie approximately in the middle between AgTaO3 and SrTiO3, being ideal for solar water splitting reactions.