Efficient photocatalytic activity of MSnO3 (M: Ca, Ba, Sr) stannates for photoreduction of 4-nitrophenol and hydrogen production under UV light irradiation

Abstract

This work reports the photocatalytic activity of MSnO3 (M = Ca, Ba, Sr) stannates for the degradation of the dangerous compound 4-Nitrophenol (4-NP), as well as for hydrogen generation starting from clear water. These stannates were prepared by a co-precipitation method. The photocatalytic degradation experiments under UV irradiation point out that the BaSnO3 stannate produced a total degradation of 4-NP after 3 h and this was due to its higher OH radical’s generation rate. This was confirmed by the high fluorescence signal (at 430 nm) produced after the excitation of the Teraphtalic acid/·OH complex, which was formed in presence of the BaSnO3 compound. The CaSnO3 and SrSnO3 stannates produced degradation percentages of 4-NP in the range of 80–95%. However, these stannates produced an innocuous compound: 4-aminophenol, which is widely used in the pharmaceutical industry. The results also indicated that the SrSnO3 stannate had the highest hydrogen production rate of 160 μmol·g−1 h−1. Scanning electron microscopy (SEM) analysis demonstrated that the stannates are formed of polyhedral nanoparticles with sizes in the range of 50–400 nm. The structural analysis by X-ray diffraction confirmed that the BaSnO3 stannate presents a cubic phase while the SrSnO3 and CaSnO3 stannates have an orthorrombic phase. Due to their good performance for photoreduction and hydrogen production, we consider that the stannates reported here could be candidates for the degradation of contaminants in water effluents or for the generation of a clean source of energy.