Efficient visible-light-responsive photocatalyst: Hybrid TiO2-Ag3PO4 nanorods

Article abstract of DOI:10.1016/j.chemphys.2019.01.015

Herein, ordered TiO₂-Ag₃PO₄ nanorods are fabricated by loading Ag₃PO₄ nanoparticles on the as-prepared brookite TiO₂ nanorods. The amount of Ag₃PO₄ nanoparticles loaded on brookite TiO₂ nanorods can be rationally optimized. These hybrid TiO₂-Ag₃PO₄ nanorods could provide large surface area, extend the visible light absorption and facilitate the charge separation, leading to efficient visible-light-driven photocatalytic performance. When evaluated as photocatalysts under visible light illumination, all the hybrid TiO₂-Ag₃PO₄ nanorods exhibit high photocatalytic activity for degrading 2-propanol. Particularly, TiO₂-Ag₃PO₄-3 enables the best photocatalytic property, which yields high acetone production of 147 ppm at 3 h and CO₂ production of 424 ppm at 11 h.

Full text of DOI:10.1016/j.chemphys.2019.01.015

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Accepted Manuscript
Efficient visible-light-responsive photocatalyst: hybrid TiO2-Ag3PO4 nanorods
Yulong Jia, Ying Ma, Lili Zhu, Jun Dong, Yinhe Lin
PII:
S0301-0104(18)31207-2
DOI:
https://doi.org/10.1016/j.chemphys.2019.01.015
CHEMPH 10282
Reference:
Chemical Physics
To appear in:
Received Date:
Revised Date:
Accepted Date:
1 November 2018
15 January 2019
15 January 2019
Please cite this article as: Y. Jia, Y. Ma, L. Zhu, J. Dong, Y. Lin, Efficient visible-light-responsive photocatalyst:
hybrid TiO2-Ag3PO4 nanorods, Chemical Physics (2019), doi: https://doi.org/10.1016/j.chemphys.2019.01.015
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Efficient visible-light-responsive photocatalyst: hybrid TiO2-Ag3PO4
nanorods
Yulong Jia,[a] Ying Ma,[a]* Lili Zhu, [a] Jun Dong, [a] Yinhe Lin, [a]
a.
School of Chemistry and Chemical Engineering, Yangtze Normal University, Chongqing 408100, PR China.
ABSTRACT
Herein, ordered TiO2-Ag3PO4 nanorods are fabricated by loading Ag3PO4 nanoparticles on the as-prepared brookite TiO2 nanorods. The amount of
Ag3PO4 nanoparticles loaded on brookite TiO2 nanorods can be rationally optimized. These hybrid TiO2-Ag3PO4 nanorods could provide large
surface area, extend the visible light absorption and facilitate the charge separation, leading to efficient visible-light-driven photocatalytic
performance. When evaluated as photocatalysts under visible light illumination, all the hybrid TiO2-Ag3PO4 nanorods exhibit high photocatalytic
activity for degrading 2-propanol. Particularly, TiO2-Ag3PO4-3 enables the best photocatalytic property, which yields high acetone production of
147 ppm at 3 h and CO2 production of 424 ppm at 11 h.
Key Words: Nanocomposites; TiO2-Ag3PO4; Visible-light-responsive; Solar energy materials
1.
Introduction
Photocatalysts have attracted numerous interests ascribed to their potential applications for energy conversion and degradation of pollutants [1-2].
Titanium dioxide (TiO2) as one of the most important photocatalysts exhibits excellent photocatalytic activity, good stability and abundant source,
enabling the extensively research on exploring efficient photocatalyst. Furthermore, brookite TiO2 has been confirmed to be superior in
photo-degradation of organic containments [3-5]. Nevertheless, the brookite TiO2 demonstrates photocatalytic response under UV-light instead of
visible light irradiation, limiting the sufficient utilization of solar light. In order to extend the visible-light-driven photocatalytic response of
brookite TiO2, fabrication of heterostructures is highly proposed [6-8]. For instance, Peng et al. prepared g-C3N4 nanodots decorated brookite TiO2
nanocubes with enhanced visible-light-driven photocatalytic activity [9]. Chen and co-authors constructed g-C3N4/anatase/brookite heterojunction
structure with improved hydrogen production under visible light [10]. It is validated that the brookite TiO2-based hetero-structured materials
 Corresponding author: E-mail: yma2017@126.com
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demonstrate efficient visible-light-driven photocatalytic performance. However, the research on brookite TiO2-based heterojunctions is limited
devoted to the difficult synthesis techniques.
Ag3PO4 [11,12] exhibit excellent visible light driven photocatalytic response ascribed to the narrow bandgap. However, the inherent fast
charge recombination and poor photostability hinder the widely research and application of Ag3PO4 on photocatalysis. To address this issue, the
strategy of coupling Ag3PO4 with other semiconductors was reported [13,14]. Herein, the well-defined brookite TiO2 nanorods are obtained by a
simple hydrothermal reaction. Subsequently, the precipitation method is adopted to yield Ag3PO4-brookite TiO2 hybrid nanorods, which effectively
extend the visible light absorption, enhance the surface area and promote charge separation. As expected, the TiO2-Ag3PO4 heterostructured
nanorods manifest distinct visible-light-driven photocatalytic performance for degrading 2-propanol. Moreover, the loading amount of Ag3PO4 can
be rationally controlled and the highest photocatalytic activity can be obtained by TiO2-Ag3PO4-3 with molar percentage of 13% for Ag3PO4.
Experimental section
All reagents are of analytic grade (Chongqing Chemical Company) and used without any further purification.
The brookite TiO2 nanorods were synthesized by a facile hydrothermal method [15] using the titanium bis(ammonium lactate) dihydroxide
(TALH) and urea as precursors. As typically, 5 mL TALH and 45 mL deionized water were added into urea (21.02 g), and then the solution was
stirred for 2 hours. Aimed to yield regular brookite TiO2 nanorods, the as-prepared solution was transferred into a Teflon cup (100 mL), which was
kept at 230 ºC for 48 h. The white powder could be collected and washed after the product cooling down to the room temperature. In order to load
Ag3PO4 on TiO2, the as-prepared brookite TiO2 (0.237 g) powder was dissolved in 50 mL deionized water, and then a certain amount of AgNO3
(0.45 g) was added into the solution. After stirring for 10 min under dark, a solution of Na2HPO4 (50 mL, the molar ratio of AgNO3 and Na2HPO4 is
controlled at 3: 1) was added into the above solution drop by drop and then was stirred for 7 hours under dark. Moreover, the amount of AgNO3 and
Na2HPO4 was optimized with the molar percentage of 2.9%, 5.8%; 13%, 23% and 37.5% for Ag3PO4 in TiO2-Ag3PO4 heterojunction.
Correspondingly, the obtained hybrid samples are marked with TiO2-Ag3PO4-1, TiO2-Ag3PO4-2, TiO2-Ag3PO4-3, TiO2-Ag3PO4-4 and
TiO2-Ag3PO4-5. Finally, the well-defined TiO2-Ag3PO4 composites can be obtained after filtration, washing and drying. For comparison, the pure
Ag3PO4 nanoparticles were obtained by the same procedure except adding the TiO2 nanorods.
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The X-ray diffraction (XRD) instrument (MiniFlex II, Rigaku Co.) was utilized to characterize the crystal phases of products. The
morphologies were investigated by scanning electron microscope (SEM). Furthermore, the UV-vis patterns were measured by the UV-vis
spectrometer (UV-2500PC, Shimadzu). The Brunauer-Emmett-Teller (BET) surface area was characterized by Quantachrome Nova 4200e. The
photocatalytic activities of samples were evaluated by degrading 2-propanol. The as-prepared powder (0.1 g) was uniformly dispread on a glass
dish (2 cm2), which was placed in a Tedlar bag with 125 mL 2-propanol (500 ppm). The absorption equilibrium was obtained by keeping the
as-prepared bag in dark for 1 hour. Then the visible light (100 mW cm-2) was gained by Xenon lamp equipped with a Yellow-44 filter and was used
as the light source to measure the photocatalytic performance. During the photocatalytic process, the amount of acetone and CO2 were evaluated by
online gas chromatography (Agilent Technologies, 3000A micro-GC, TCD detector) equipped with OV1 and PLOT-Q columns.
3. Results and discussion
Figure 1. SEM images of (A) pristine brookite TiO2 nanorods (B) TiO2-Ag3PO4-1 (C) TiO2-Ag3PO4-2 (D) TiO2-Ag3PO4-3 (E) TiO2-Ag3PO4-4 (F)
TiO2-Ag3PO4-5.
The morphologies and structures of as-prepared samples are characterized by SEM images. As can be seen from Figure 1A, the pristine
brookite TiO2 exhibits regular prismatic nanorod shape with smooth surface. Moreover, the nanorods display an average length of 100 nm and
diameter of 20 nm. With modification of Ag3PO4, the nanoparticles were loaded on nanorods (Figure 1B-F). With the molar percentage of Ag3PO4
3