To investigate the effect of Gd doping on photocatalytic activity of BiFeO3 (BFO), Gd-doped BFO nanoparticles containing different Gd doping contents (Bi(1−x)GdxFeO3, x = 0.00, 0.01, 0.03, 0.05) were synthesized using a facile sol-gel route. The obtained products were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectra, and ultraviolet-visible diffuse reflectance spectroscopy, and their photocatalytic activities were evaluated by photocatalytic decomposition of Rhodamine B in aqueous solution under visible light irradiation. It was found that the Gd doping content could significantly affect the photocatalytic activity of as-prepared Gd-doped BFO, and the photocatalytic activity increased with increasing the Gd doping content up to the optimal value and then decreased with further enhancing Gd doping content. To elucidate the enhanced photocatalytic mechanism of Gd-doped BFO, the trapping experiments, photoluminescence, photocurrent and electrochemical impedance measurements were performed. On the basis of these experimental results, the enhanced photocatalytic activities of Gd-doped BFO could be ascribed to the increased optical absorption, the efficient separation and migration of photogenerated charge carriers as well as the decreased recombination probability of electron-hole pairs derived from the Gd doping effect. Meanwhile, the possible photocatalytic mechanism of Gd-doped BFO was critically discussed.
The
oxygen evolution reaction (OER) plays a paramount role in a
variety of electrochemical energy conversion devices, and the exploration
of highly active, stable, and low-cost electrocatalysts is one of
the most important topics in this field. The exfoliated black phosphorus
(EBP) nanosheet with a two-dimensional (2D) layered structure has
high carrier mobility but is limited by excessive oxygen-containing
intermediate absorption and fast deterioration in air. We here report
the fabrication of nanohybrids of amorphous CoFeB nanosheets on EBP
nanosheets (EBP/CoFeB). The 2D/2D heterostructure, thanks to the electronic
interactions and oxygen affinity difference between EBP and CoFeB
nanosheets, is capable of balancing the oxygen-containing intermediate
absorption to an optimal status for facilitating the OER process.
While the crystalline EBP contributes to the improved conductivity,
the amorphous coating protects EBP and thus ensures the catalytic
stability. The EBP/CoFeB electrocatalyst shows excellent OER performance
with an ultralow overpotential of 227 mV at 10 mA cm–2 with an ultrasmall Tafel slope of 36.7 mV dec–1 with excellent stability. This study may inspire more researches
to develop heterostructured nanohybrid electrocatalysts for a diversity
of electrochemical reactions.
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