Ag₃PO₄@UMOFNs Core–Shell Structure: Two-Dimensional MOFs Promoted Photoinduced Charge Separation and Photocatalysis

Abstract

Metal-organic frameworks (MOFs) are a new type of functional material that is self-assembled by metal ions and organic ligands. In this paper, a bimetal-organic framework was synthesized and stripped into two-dimensional nanosheets structure via an ultrasonic method. We coated the UMOFNs (ultrathinning MOFs into two-dimensional nanosheets) on AgPO nanoparticles to obtain AgPO@UMOFNs core-shell photocatalysts. Under visible-light irradiation, the degradation of phenol was 100% within 16 min, and the degradation of biphenyl A was 98.9% within 20 min via AgPO@UMOFNs (5 wt %). These values were 1.6- and 1.8-times higher than AgPO, respectively. The activity of the AgPO@UMOFNs increased due to the synergistic effects. The π-π bonds of the organic ligands and weak interactions between UMOFNs and AgPO collectively promote charge transfer. In addition, matching energy-level structures and a sufficiently large contact area accelerate the separation of the photogenerated charges and improve the activity. This remarkably improves the photocatalytic activity.

Preparation of the floating HGMs-Ag3PO4 composites and the visible-light photocatalytic properties

“…Compared with the same mass of pure Ag 3 PO 4 , the mass of Ag 3 PO 4 contained in HGMs3 is only 7.68% (≈8 wt% of the composite shown in table 1), but its photocatalytic efficiency (k=0.0444 min −1 ) is nearly twice that of pure Ag 3 PO 4 (k=0.0242 min −1 , see figure 7(b)). However, as shown in table 1, to enhance the photocatalytic activity of Ag 3 PO 4 -composite, the proportion of Ag 3 PO 4 often exceeds 50% [18,20,24,25,30]. Therefore, the superiority of the HGMs-Ag 3 PO 4 composite is obvious.…”

“…Yi [7] reported Ag 3 PO 4 had excellent performance on the evolution of O 2 from water splitting and remove of organic dyes under the visible-light exposure due to the capability to effectively separate photoexcited electrons and holes with suitable band gap of 2.45 eV, achieving a quantum yield of up to 90% (λ>420 nm), thus extending a new application of Ag 3 PO 4 in the field of photo-catalysis. The visible-light photo-catalytic degradation properties of Ag 3 PO 4 can be further enhanced by controlling its morphology [8], feature size [9], surface area [10] and low-index facets [11], by assembling with other semiconductors such as TiO 2 [6,12,13] , Fe 3 O 4 [14], AgX (X=Cl, Br, I) [15][16][17], In(OH) 3 [18], BiVO 4 [19], MOF [20], MoSe 2 [21], CeO 2 [22], N-Sr 2 Nb 2 O 7 [23], g-C 3 N 4 [24], polyaniline [25] and carbon based materials including graphene (GR) [26], graphene oxide (GO) [27], reduced graphene oxide (RGO) [28], carbon quantum dots (CQDs) [29]and carbon nanotubes (CNTs) [30] to construct a surface heterojunction, and the doping of atomic impurities [31]. The photo-catalytic activity performance of Ag 3 PO 4 -composites has been summarized into table 1.…”

“…The photo-catalytic activity performance of Ag 3 PO 4 -composites has been summarized into table 1. There are many typical organic pollutants to evaluate the photocatalytic activity of Ag 3 PO 4 -composites photocatalysts, such as using organic dyes (methylene blue-MB [8,13,24,30], rhodamine B-RhB [12,18,19], methyl orange-MO [22,29], etc), preservatives (methylparaben [16], phenol [20,25,28], etc), insecticides (imidacloprid [14], etc), antibiotic (tetracycline [26], etc). Compared with pure Ag 3 PO 4 photocatalyst, the Ag 3 PO 4 -composites have a certain degree of improvement in the photocatalytic activity on different organic pollutants.…”

“…Compared with pure Ag 3 PO 4 photocatalyst, the Ag 3 PO 4 -composites have a certain degree of improvement in the photocatalytic activity on different organic pollutants. Nevertheless, in order to achieve high photocatalytic performance, Ag 3 PO 4 needs to account for a large proportion even in the Ag 3 PO 4 composite photocatalyst [20,24,25,30]. The high cost of raw materials AgNO 3 and the difficulty of separating as well as recovering Ag 3 PO 4 -based photo-catalysts from the reaction suspension limit the large-scale practical application of the photo-catalysts [32].…”

Application of mixture experimental design for photocatalytic ammonia degradation by sunlight‐driven WO 3 ‐Ag 3 PO 4 ‐ZnO ternary photocatalysts

“…[29][30][31] Among the aforementioned methods, construction of heterostructural semiconductors is a viable method leading to the improvement of structural stability, light absorbance range, and lifetime of the charge carriers. For instance, Liang et al 32 have developed a series of Ag 3 PO 4 -UMOFNs core-shell structure photocatalysts as highly efficient and stable photosensitive material. Liu et al 33 have also used Ag 3 PO 4 photocatalyst coated by P3HT, achieving a stable and high active photocatalyst under visible-light irradiation.…”