Photocatalyst Interface Engineering: Spatially Confined Growth of ZnFe₂O₄ within Graphene Networks as Excellent Visible‐Light‐Driven Photocatalysts

Abstract

High‐performance photocatalysts should have highly crystallized nanocrystals (NCs) with small sizes, high separation efficiency of photogenerated electron–hole pairs, fast transport and consumption of photon‐excited electrons from the surface of catalyst, high adsorption of organic pollutant, and suitable band gap for maximally utilizing sunlight energy. However, the design and synthesis of these versatile structures still remain a big challenge. Here, we report a novel strategy for the synthesis of ultrasmall and highly crystallized graphene–ZnFe2O4 photocatalyst through interface engineering by using interconnected graphene network as barrier for spatially confined growth of ZnFe2O4, as transport channels for photon‐excited electron from the surface of catalyst, as well as the electron reservoir for suppressing the recombination of photogenerated electron–hole pairs. As a result, about 20 nm ZnFe2O4 NCs with highly crystallized (311) plane confined in the graphene network exhibit an excellent visible‐light‐driven photocatalytic activity with an ultrafast degradation rate of 1.924 × 10−7 mol g−1 s−1 for methylene blue, much higher than those of previously reported photocatalysts such as spinel‐based photocatalysts (20 times), TiO2‐based photocatalysts (4 times), and other photocatalysts (4 times). Our strategy can be further extended to fabricate other catalysts and electrode materials for supercapacitors and Li‐ion batteries.

Advances in Magnetically Separable Photocatalysts: Smart, Recyclable Materials for Water Pollution Mitigation

“…In a similar work by Yang et al, ZnFe 2 O 4 nanocrystals were confined within an interconnected graphene network, which served as dispersing agents, as transport channels for electrons, and as electron scavengers and reservoirs to minimise recombination. Enhanced visible light photocatalytic degradation of MB was observed over the nanocomposite photocatalyst [176]. In the RGO/ZnFe 2 O 4 nanocomposite, electrons are excited by visible light from the valence band to the conduction band of ZnFe 2 O 4 , and these electrons quickly transfer to the RGO skeleton where they are trapped by adsorbed oxygen to form superoxide radicals (Figure 6a).…”

“…In the RGO/ZnFe 2 O 4 nanocomposite, electrons are excited by visible light from the valence band to the conduction band of ZnFe 2 O 4 , and these electrons quickly transfer to the RGO skeleton where they are trapped by adsorbed oxygen to form superoxide radicals (Figure 6a). The holes are confined to the valence band of ZnFe 2 O 4 where they directly oxidise the pollutants since they are not positive enough to react with water to form the hydroxyl radicals [175,176]. More interestingly, the RGO/ZnFe 2 O 4 nanocomposites showed good stability and recyclability and were easily separable using an external magnetic field owing to the good magnetic response (Figure 6b).…”

Synthesis, Property Characterization and Photocatalytic Activity of the Polyaniline/BiYTi2O7 Polymer Composite

“…Traditionally, for improving the photocatalytic efficiency of photocatalysts, the bandgap of photocatalysts or loaded cocatalysts plays an important role in photocatalyst system. Therefore, efficient catalysts that can generate electron–hole pairs under visible light irradiation should be developed [ 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 , 64 ]. Among them, A 2 B 2 O 7 compounds with narrow band gaps have been proven to be good candidates for photocatalytic degradation of organic pollutants under visible light irradiation.…”

Magnetic ZnFe2O4@chitosan encapsulated in graphene oxide for adsorptive removal of organic dye

“…3b. Two peaks at a binding energies of 1021.7 eV (Zn 2p 3/2 ) and 1044.8 eV (Zn 2p 1/2 ) correspond to Zn 2+ in the 18 The deconvoluted C 1s spectra centered at the binding energies of 287.5, 286.3, and 284.7 eV were assigned to C-O-C, C-OH and C]C, respectively, (Fig. 3d).…”