A direct Z-scheme CdFe 2 O 4 /g-C 3 N 4 hybrid systems with different weight ratios of CdFe 2 O 4 nanoparticles were successfully designed and constructed for ceftiofur sodium photodegradation. The as-obtained CdFe 2 O 4 /g-C 3 N 4 hybrid samples composed of CdFe 2 O 4 nanoparticles and g-C 3 N 4 nanosheets were systematically characterized by different techniques including X-ray diffraction, scanning electron microscope, transmission electron microscope, Fourier transform infrared spectroscopy , X-ray photoelectron spectroscopy, UV–vis DRS , chemical oxygen demand, inductively coupled plasma mass spectrometer, photochemical test and electron spin resonance spectrometer technique. The optimal photocatalytic activity for ceftiofur sodium photodegradation was achieved by modulating the weight ration between CdFe 2 O 4 nanoparticles and g-C 3 N 4 nanosheets. The result from photocatalytic tests indicate that CdFe 2 O 4 /g-C 3 N 4 -2 hybrid sample exhibit highly efficient photocatalytic activity towards ceftiofur sodium removal in comparison with pristine CdFe 2 O 4 nanoparticles and pure g-C 3 N 4 nanosheets. Meanwhile the excellent photocatalytic stability of CdFe 2 O 4 /g-C 3 N 4 -2 hybrid sample was also verified during recycling runs towards photocatalytic ceftiofur sodium degradation. The significant enhancement of photocatalytic activity was attributed to the Z-scheme charge separation and transfer based on the construction of tight heterogeneous interface and well-matched band potentials. We expect this research to provide a new insight into the design and preparation of direct Z-scheme hybrid photocatalysts for environmental remediation.
The rare-earth ion doping in nanocrystals has the advantage on improving the interested properties. As one of rare-earths, the trivalent samarium ion (Sm 3 + ) was used as a dopant. The precursor of Sm 3 + -doped cadmium ferrite (CdFe 2 O 4 ) nanocrystals was reacted in water-soluble polymeric nanoreactors as a dispersed phase in miniemulsion, and then calcinated to form doped nanocrystals. The 1% Sm 3 + -doped nanocrystal in small size exhibited the smaller narrow gap energy and weak photoluminescent emission intensity; which attributed to the positive influences on the photocatalytic degradation. The selected Sm 3 + -doped spinel ferrite nanocrystals provide a unique catalyzer for organic compound photodegradation.
Despite the recognized potential of two-dimensional transition metal dichalcogenides (2D TMDs) as effective sensitizers for metal oxides, comparative insights into their specific sensitization effects on spinel ferrites remain lacking. Herein, MoS 2 -CdFe 2 O 4 and WS 2 -CdFe 2 O 4 composites were synthesized via an in-situ solvothermal-calcination strategy. Characterization results confirmed that the incorporation of TMDs effectively modulated the microstructure and surface properties of CdFe 2 O 4 . Specifically, the WS 2 -CdFe 2 O 4 (WDF-10) had a larger specific surface area (10.14 m 2 /g) and pore volume than the MoS 2 -CdFe 2 O 4 (MDF-10), exposing more active sites. XPS suggests an increased fraction of defect-related/adsorbed oxygen species in the composites. Gas-sensing tests revealed performance differences: the WDF-10 sensor exhibited a remarkable response to 100 ppm formaldehyde at 140°C, approximately 2.5 times higher than the MDF-10. Meanwhile, the MDF-10 sensor demonstrated reduced response/recovery times, enhanced quantitative precision, and remarkable long-term stability. The sensitization mechanism is attributed to the synergistic effect of increased specific surface area and the proposed formation of p-n heterojunctions. Energy band analysis suggests that WS 2 , with its unique band alignment, may induce a stronger depletion layer modulation on CdFe 2 O 4 , thereby enhancing the response. This work demonstrates that surface sensitization with MoS 2 or WS 2 is an effective strategy to enhance the gas-sensing performance of spinel ferrites.
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