Preparation of ZnFe₂O₄ nanostructures and highly efficient visible-light-driven hydrogen generation with the assistance of nanoheterostructures

Abstract

ZnFe 2 O 4 is a promising visible-light-driven photocatalyst with high energy level CBM for hydrogen generation. However, it could only be synthesized in the bulk form and its photocatalytic activities are limited by the rapid recombination of photo-generated carriers. Here, we report the preparation of a ZnFe 2 O 4 nanostructure in ultrathin hollow sphere morphology with a 10 nm thick shell, which could shorten the diffusion distance of photo-generated carriers to minimize their interior recombination.Furthermore, ZnFe 2 O 4 /ZnO nanoheterostructures, containing 15 nm size heterojunctions, could be synthesized facilely. We have found that this unique structure endows ZnFe 2 O 4 /ZnO with a large separation of photo-generated carriers. The hydrogen generation rate of ZnFe 2 O 4 /ZnO nanoheterostructures without co-catalysts is up to 2.15 mmol h À1 g À1 under visible light irradiation (l > 420 nm), which is 45 times higher than the best yields ever reported for ZnFe 2 O 4 -based photocatalysts. These research results provide a general and effective route to synthesize other nanoheterostructures for a variety of applications.

Enhanced photoelectrochemical and photocatalytic behaviors of MFe2O4 (M = Ni, Co, Zn and Sr) modified TiO2 nanorod arrays

“…Similar to the Ni 2 p peaks in NiFe 2 O 4 /TiO 2 NRAs, the Co 2 p XPS spectra recorded from the CoFe 2 O 4 /TiO 2 NRAs sample, containing Co 2 p 3/2 (781.03 eV, Co 2+ in Tet-site) and Co 2 p 1/2 (796.67 eV, Co 2+ in Tet-site), indicate that Co 2+ exists in the CoFe 2 O 4 /TiO 2 NRAs according to the literature reports33. For the ZnFe 2 O 4 /TiO 2 NRAs, the recorded Zn 2 p XPS spectra indicate that Zn 2+ exists in the ZnFe 2 O 4 /TiO 2 NRAs, which is also consistent with literature reports3435. Furthermore, the manganese valences were determined by the position of the multiplet splitting of Sr 2 p peaks, the positions of Sr 2 p 3/2 and Sr 2 p 1/2 were all assigned to Sr 2+ .…”

Hollow Nanostructures for Photocatalysis: Advantages and Challenges

“…Nevertheless, there is still a lack of convincing experimental or theoretical evidence for this model. It is imperative to fundamentally investigate the junctions constructed by numerous particles, as well as their contribution to the global photocatalytic performance . Additionally, Z‐scheme systems with hollow nanostructures have also been prepared, which exhibit improved photocatalytic performance due to the directed charge separation and transfer spatially …”

Selective Deposition of Silver Oxide on Single‐Domain Ferroelectric Nanoplates and Their Efficient Visible‐Light Photoactivity

“…Althoughi ti sd ifficult for us to figure out the detailed photocatalytic mechanisms of the composite towards the three kinds of dyes, the intrinsic properties of the composite are able to be confirmed. The maximum values of the valance band (VBM) of pure PTO nanoplates andA g 2 Ow erem easured simultaneously [28] and were determined to be + 0.92 and + 0.72 eV (Figure 7a), respectively.C ombined with the band gaps of the two materials ( Figure S5 in the Supporting Information), the relative locations of the conduction bands are calculated and apossible photocatalytic mechanism is proposed ( Figure 7b). [29] Driven by the large difference between the positions of the conduction bands andt he polarization effect near the surface of the ferroelectric PTO substrate, [3a, 12b] the photogenerated electrons mainly concentrate at the interface area of the composite.T his is in accordance with the analysis results of XPS and is furtherd emonstrated by photodepositing Pt on the composite (Figure S11i nt he Supporting Information).…”