Novel Z-scheme Sr2MgSi2O7:Eu2+,Dy3+/Ag3PO4 photocatalyst for round-the-clock efficient degradation of organic pollutants and hydrogen production

Abstract

The photocatalytic reaction can carry out only under light irradiation, which limits the application of photocatalytic technology in the wastewater treatment and hydrogen production under no-light condition. In this study, Sr2MgSi2O7:Eu2+,Dy3+ with unique luminescence property was combined with Ag3PO4 to construct a novel Z-scheme Sr2MgSi2O7:Eu2+,Dy3+/Ag3PO4 photocatalyst. The morphology, structure, luminescence and photoelectric properties of the prepared samples were investigated by various characterization techniques. Some important influencing factors such as the mass ratios of Sr2MgSi2O7:Eu2+,Dy3+ and Ag3PO4, illumination times and cycling times were investigated. The results indicate that the Z-scheme Sr2MgSi2O7:Eu2+,Dy3+/Ag3PO4 photocatalyst with the best mass ratio (15:1) possesses superior photocatalytic activity. The LEV degradation rate is 81.94 % and the hydrogen production reaches 491 μmol/g under simulated sunlight irradiation for 1.0 h. The long-afterglow Sr2MgSi2O7:Eu2+,Dy3+ material can continue to support the photocatalytic reaction even after the light is turned off. The final LEV degradation is 86.84 % and the final hydrogen production amount reaches 591 μmol/g after the light is turned off for 3.0 h. Meanwhile, the process and possible mechanism of the round-the-clock photocatalytic LEV degradation with simultaneous hydrogen production were reported for the first time. This work cleverly uses the long-afterglow Sr2MgSi2O7:Eu2+,Dy3+ material combined with Ag3PO4 to form a novel Z-scheme photocatalyst, which realizes the organic pollutant degradation with simultaneous hydrogen production under the light on/off conditions, providing a new strategy for the round-the-clock efficient utilization of the photocatalyst.