The efficient treatment of dye wastewater has been a hot topic of environment field. The integration of adsorption and photocatalytic degradation via fabrication of bi-component heterojunction photocatalyst is considered as a facile and effective strategy to enhance the dye elimination efficiency. In this report, a Z-scheme heterojunction material, SrTiO 3 (La,Cr)/WO 3 with bifunction of adsorption and photocatalysis was successfully synthesized for efficient removal of methylene blue (MB) under visible light irradiation. The morphology and microstructure characterization demonstrates that the SrTiO 3 (La,Cr) nanoparticles are uniformly decorated on the WO 3 nanosheets, forming an intimate heterojunction interface. MB degradation results indicate that the removal efficiency by the synergistic adsorption-photocatalysis process is greatly improved compared to pure WO 3 and SrTiO 3 (La,Cr) with the adsorption and photocatalytic activity closely related to the composition of the material. The possible mechanism for the enhanced photocatalytic activity could be ascribed to the formation of a Z-scheme heterojunction system based on active species trapping experiments. Furthermore, the investigations of adsorption kinetics and isotherm show that the adsorption process follows pseudo-second-order kinetic model and Langmuir isotherm, respectively. Due to the synergistic advantages of negative zeta potential, large surface area and accelerated separation of photogenerated carriers driven by Z-scheme heterojunction, SrTiO 3 (La,Cr)/WO 3 exhibits excellent adsorption-photocatalytic performance and stability on MB removal, which could be potentially used for practical wastewater treatment.
Plasmonic-driven photocatalyst have outstanding solar driven surface plasmon resonance (SPR) characteristics, and it is a prospective approach to improve photocatalytic performance. Herein, plasmonic Co metal decorated SrTiO 3 : La/Cr hollow cubes was developed and constructed by template-free hydrothermal method. The photocatalyst possesses the merits of the hollow structure with large specific surface area and strong light absorption. The intimate contact between Co and SrTiO 3 : La/Cr promotes the interfacial charge transfer. Co-SrTiO 3 : La/Cr manifests the superior photocatalytic performance toward water splitting for hydrogen evolution compared with that of other cocatalyst. And the H 2 evolution exceeds 210 μmol·g −1 ·h −1 under the optimum of the amount of 1.25wt% Co NPs. The mechanism of the enhanced performance comes from the improvement of light absorption in the visible-light region induced by SPR, as well as the efficient interfacial separation and transport of charge carriers on the photocatalyst facilitated by the local electromagnetic fields of plasmonic Co metal. Graphical Abstract
Junzhe Jiang,Yushuai Jia,Yabin Wang,Ruifeng Chong,Liping Xu,Xin Liu
Antibiotic has become an important organic contaminant in surface water, which poses a huge threat to human health and ecosystem. SrTiO 3 is an attractive perovskite structured semiconductor material and shows promising applications in photocatalysis . Herein, a series of lanthanum and chromium codoped SrTiO 3 (denoted as SrTiO 3 (La,Cr)- x ) with different dopant amount of La and Cr have been successfully fabricated via a facile sol-gel hydrothermal method and employed as efficient photocatalysts for the elimination of tetracycline (TC) from aqueous solution under visible-light irradiation. It indicates that the photocatalytic performance is highly dependent on the La and Cr content in the samples. Among the catalysts, the porous SrTiO 3 (La,Cr)-6 spheres with a moderate dopant amount exhibit the best photocatalytic activity for TC removal, which is approximately 4.4 and 2.3 times as superior as SrTiO 3 (La,Cr)-2 with the least dopants and SrTiO 3 (La,Cr)-8 with the most dopants, respectively. Detailed characterizations reveal that the significant improvement of photocatalytic activity is attributed to the increasing molar ratio of Cr 3+ /Cr 6+ , which can be facilely adjusted by tuning the doping amount of La and Cr during the synthesis process. In addition, the catalyst shows excellent photocatalytic stability and can be recycled over ten times with negligible activity decline. Active species trapping experiments demonstrate that superoxide radicals, holes and hydroxyl radicals are responsible for TC degradation. On the basis of the intermediate products identified using HPLC-MS, four possible reaction pathways and TC degradation mechanism have been put forward. This study offers an effective strategy to modulate the photocatalytic properties of SrTiO 3 by simple tuning the dopant content for environment and energy applications, which can be facilely extended to the modification of other semiconductors.
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