Polymerizable complex synthesis of SrTiO3:(Cr/Ta) photocatalysts to improve photocatalytic water splitting activity under visible light

Abstract

Cr/Ta co-doped SrTiO3 (STO:Cr/Ta) photocatalysts with high photocatalytic activity for water splitting under visible light have been synthesized by a polymerizable complex (PC) method. UV–vis diffuse reflectance spectra (DRS) showed that the Cr/Ta co-doping extended the absorption edge of STO to visible light region at the wavelength of 540nm. Calculations based on density functional theory (DFT) indicated that, after doping, Cr 3d and O 2p orbits formed new impurity states within the forbidden gap of STO and facilitated the excitation of photons with low energy, as the Ta was mainly used to restrain the appearance of undesired Cr6+. The photoelectrochemical measurements and XRD, SEM, BET analysis revealed that the excellent photocatalytic performance of photocatalyst prepared by a PC method was attributed to the high crystalline quality as well as relative large specific surface area. The photocatalytic activity of STO: (1% Cr/Ta) for H2 evolution prepared by a PC method is 10 times higher than that of the sample prepared by a solid state reaction (SSR) method. The Pt/STO: (2% Cr/Ta) calcined at 1100°C possessed the highest photocatalyitc activity for water splitting under visible light, thereby producing the average rate of H2 evolution of 122.6μmolh−1 (ca. 2.6% AYQ) measured at λ=420nm. Also, under a Z-scheme system, the Pt/STO: (2% Cr/Ta) exhibited AQY as high as 1.52% at λ=420nm for overall water splitting while Pt/WO3 acting as an O2 evolution photocatalyst.