Abstract
Pt nanowire-anchored dodecahedral Ag3PO4{110} was constructed for organics photodegradation. SEM and TEM images confirmed that the Pt nanowires were grafted on dodecahedral Ag3PO4, which was entirely bounded by {110} facets. All the X-ray diffraction peaks of the samples were indexed to the body-centered cubic phase of Ag3PO4, indicating that Pt nanowire-anchored dodecahedral Ag3PO4 well maintained the original crystal structure. The rhombic dodecahedral Ag3PO4 entirely bounded by {110} facets achieved high photocatalytic activity. Due to the formation of a Schottky barrier, the Pt nanowires improved the separation of the charge carriers of Ag3PO4. Furthermore, they provided a fast expressway to transfer the photogenerated electrons and prolonged the lifetime of the charge carriers via long-distance transport, resulting in the accumulation of holes on Ag3PO4 for organics degradation. More importantly, the Pt nanowires improved the reduction potential of the photogenerated electrons for O2 reduction to ·O2−, which enhanced the photocatalytic activity and anti-photocorrosion properties of Ag3PO4. We found that 99.5% of Rhodamine B (RhB) could be removed over 0.5ωt% Pt nanowire-anchored dodecahedral Ag3PO4 within 10 min. Even after 10 cycles, the photocatalytic activity was still high. photoluminescence (PL), time-resolved photoluminescence (TRPL), UV–vis diffuse reflectance spectra (UV–visDRS), and photoelectrochemical analysis showed that Pt nanowire-anchored dodecahedral Ag3PO4 exhibited lower bandgap, higher photocurrent intensity, better electronic conductivity, and longer charge carriers lifetime than other types of Ag3PO4 crystals. Radical trapping experiments and electron paramagnetic resonance (EPR) analysis demonstrated that the holes were the main active species for organics photodegradation.
Highlights
IntroductionExposure of high-energy crystal facets can improve the photocatalytic activity
Ag3 PO4 has been considered as the most potential visible-light photocatalyst due to its high quantum efficiency (90%, >420 nm) and positive valence band (VB = +2.9 eV) [1,2]
In the system of silver acetate/acetic acid, CH3 COO groups could facilitate the formation of high-energy facets {110} in Ag3 PO4, promoting the crystal growth of uniform rhombic dodecahedrons (Figure 1B and Figure S1)
Summary
Exposure of high-energy crystal facets can improve the photocatalytic activity. Our previous work indicated that 3D core–shell CQDs(carbon quantum dots)/Ag3 PO4 @benzoxazine tetrapod with exposure of more {110} facets could achieve higher visible-light photocatalytic activity and anti-photocorrosion [12]. Most of the Ag3 PO4 -based crystals were polycrystals bounded by different facets, which resulted in partial exposure of the {110} facets. Monocrystals could be entirely bounded by the same facets; monocrystalline Ag3 PO4 might entirely expose its {110} facets. For this reason, monocrystal Ag3 PO4 -based photocatalysts are expected to have significantly improved photocatalytic activity
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