Yang Liwei,Li Lele,Li Fen,Zheng Hejie,Li Tongtong,Liu Xiaoqiang,Zhu Jichun,Zhou Yanmei,Alwarappan Subbiah
Herein, a photoelectrochemical (PEC) aptasensing platform was designed by integrating surface oxygen vacancy (OV) defects, Ti 3+ self-doping, the heterojunction, and resonance energy transfer (RET) effect into one platform for the detection of diclofenac sodium (DCF). Briefly, OV defects were introduced on TiO 2 nanospheres with simultaneous Ti 3+ self-doping, followed by a well-separated deposition of FeVO 4 nanoparticles on TiO 2 to obtain a Ti 3+ -O-TiO 2 /FeVO 4 heterojunction. The surface modification of OVs, Ti 3+ doping, and deposition of FeVO 4 were confirmed by SEM, XPS, EPR, DRS, and PEC measurements. The surface OVs and doping of Ti 3+ species created a new donor (defect) energy level under the conduction band of TiO 2 , which minimized the bandgap and thereby improved the visible light absorption of TiO 2 . Moreover, the capture of photo-excited electrons by surface OVs could hinder the electron-hole recombination. Due to the intimate surface contact and perfect energy matching between TiO 2 and FeVO 4 , the formation of heterojunction decreased the bandgap and facilitated the electron-hole separation of TiO 2 . All these above events contributed to the enhancement of the PEC signals, which were then quenched by the RET effect between Ti 3+ -O-TiO 2 /FeVO 4 and Au nanoparticle (AuNP)–labeled cDNA that had been attached to its complementary DCF aptamer on Ti 3+ -O-TiO 2 /FeVO 4 |ITO. The addition of target-DCF detached AuNP-labeled cDNA from the electrode to recover the photocurrent, resulting in a “signal-on” PEC aptasensor that exhibited a 0.1–500-nM linear range and a detection limit of 0.069 nM for DCF, attributed to the excellent amplification of the proposed aptasensing platform.
Jingtao Zhang,Mengwan Zhai,Xueying Wang,Shurui Liu,Lijuan Zhang,Xing Liu,Yao Geng,Xiaodong Sun,Bingkun Liu
In the present work, Ti 3+ -self-doped TiO 2 heterostructure photocatalysts were prepared by coupling with different additions of palladium quantum dots by means of deposition-reduction methodology. The electron paramagnetic resonance (EPR) analysis indicated the existence of Ti 3+ in synthesized samples. The transmission electron microscopy (TEM) images presented the modification of TiO 2-x nanoparticles by coupling with nano palladium. Photoluminescence (PL) results demonstrated the lowest charge carrier recombination rate in 5% Pd/TiO 2-x composites. Photocatalytic performances of photocatalysts were evaluated by degrading Tetracycline (TC) and inactivating Escherichia coli ( E. coli ) and Fusarium oxysporum f. sp. Vasinfectum ( Fov ) with the presence of visible light , in which an enhanced photocatalytic degradation and inactivation activity was found in all Pd coupled composites with the highest efficiency in 5% Pd/TiO 2-x . The improved photocatalytic activity of Pd/TiO 2-x was associated to the generation of more hydroxyl radicals (•OH) and superoxide anions radicals (•O 2- ) during photocatalytic process which were demonstrated by the electron spin-resonance spectroscopy (ESR) technique. Moreover, 5% Pd/TiO 2-x composites were found to remain high photocatalytic properties in a circulating photo-disinfection system.
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