Abstract
In this study, TiO2/Ag3PO4 composites based on anatase TiO2 nanocrystals with co-exposed {101}, {010}/{100}, {001} and [111]-facets and Ag3PO4 microcrystals with irregular and cubic-like polyhedron morphologies were successfully synthesized by combining hydrothermal and ion-exchange methods. The anatase TiO2 nanocrystals with different high-energy facets were controllably prepared via hydrothermal treatment of the exfoliated [Ti4O9]2−/[Ti2O5]2− nanosheet solutions at desired pH values. The Ag3PO4 microcrystal with different morphologies was prepared via the ion-exchange method in the presence of AgNO3 and NH4H2PO4 at room temperature, which was used as a substrate to load the as-prepared anatase TiO2 nanocrystals on its surface and to form TiO2/Ag3PO4 heterostructures. The apparent rate constant of the pH 3.5-TiO2/Ag3PO4 composite was the highest at 12.0 × 10−3 min−1, which was approximately 1.1, 1.2, 1.4, 1.6, 13.3, and 24.0 fold higher than that of pH 0.5-TiO2/Ag3PO4 (10.5 × 10−3 min−1), pH 7.5-TiO2/Ag3PO4 (10.2 × 10−3 min−1), pH 11.5-TiO2 (8.8 × 10−3 min−1), Ag3PO4 (7.7 × 10−3 min−1), blank sample (0.9 × 10−3 min−1), and the commercial TiO2 (0.5 × 10−3 min−1), respectively. The pH 3.5-TiO2/Ag3PO4 composite exhibited the highest visible-light photocatalytic activity which can be attributed to the synergistic effects of its heterostructure, relatively small crystal size, large specific surface area, good crystallinity, and co-exposed high-energy {001} and [111]-facets. The as-prepared TiO2/Ag3PO4 composites still exhibited good photocatalytic activity after three successive experimental runs, indicating that they had remarkable stability. This study provides a new way for the preparation of TiO2/Ag3PO4 composite semiconductor photocatalysts with high energy crystal surfaces and high photocatalytic activity.
Highlights
With the rapid development of industrialization, energy and environmental crises have become the key factors restricting the sustainable development of human society
In comparison to the commercial TiO2 and the pure Ag3PO4 samples, the heterostructured TiO2/Ag3PO4 composites exhibited good photocatalytic activity for the degradation of rhodamine B under visible light irradiation, which can be attributed to the separation of the eÀ and h+ inhibits the charge recombination
The photocatalytic activities of the as-synthesized TiO2/Ag3PO4 composites were evaluated by monitoring the degradation of rhodamine B (RhB)
Summary
With the rapid development of industrialization, energy and environmental crises have become the key factors restricting the sustainable development of human society. Since the pioneering work by Wen and coworkers on the synthesis of nanometer-sized anatase TiO2 crystals with a large percentage of {101} facets by using the delaminated [Ti1.73O4]1.07À nanosheets as the precursor, there has been intensive interest in the exible and controllable synthesis of anatase crystals with varied high-energy facets, such as {001}, {010}/{100}, {110} and {111} facets.. We synthesized high-energy {010}, {001}, and [111]-faceted anatase TiO2 nanocrystals by using the delaminated [Ti4O9]2À and [TiO3]2À nanosheets as the precursors in the presence and absence of capping agent, which displayed superior photocatalytic and photovoltaic performance.. The exposed high-energy crystal surface of anatase TiO2 crystals will be conducive to improving the photocatalytic activity and dyesensitized solar energy performance, anatase TiO2 crystals cannot suitable for applications under visible light irradiation due to its wide band gap (3.2 eV), resulting in the lower energy conversion efficiency in practical application. Paper the dominant exposed {101} crystal facets (more than 94%) on its surface. Since the pioneering work by Wen and coworkers on the synthesis of nanometer-sized anatase TiO2 crystals with a large percentage of {101} facets by using the delaminated [Ti1.73O4]1.07À nanosheets as the precursor, there has been intensive interest in the exible and controllable synthesis of anatase crystals with varied high-energy facets, such as {001}, {010}/{100}, {110} and {111} facets. Recently, we synthesized high-energy {010}, {001}, and [111]-faceted anatase TiO2 nanocrystals by using the delaminated [Ti4O9]2À and [TiO3]2À nanosheets as the precursors in the presence and absence of capping agent, which displayed superior photocatalytic and photovoltaic performance. the exposed high-energy crystal surface of anatase TiO2 crystals will be conducive to improving the photocatalytic activity and dyesensitized solar energy performance, anatase TiO2 crystals cannot suitable for applications under visible light irradiation due to its wide band gap (3.2 eV), resulting in the lower energy conversion efficiency in practical application.
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