Synthesis and characterization of Ag@ETS-10 core-shell heterostructured photocatalyst for visible light photocatalysis

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MRS Advances © 2020 Materials Research Society DOI: 10.1557/adv.2020.297

Synthesis and characterization of Ag@ETS10 core-shell heterostructured photocatalyst for visible light photocatalysis Emily T. Buttafuoco1, Juliusz Warzywoda2, Albert Sacco Jr.3, Mariam N. Ismail1,* 1

Chemistry and Physics Department, Simmons University, Boston, MA 02115

2

Materials Characterization Center, Whitacre College of Engineering, Texas Tech University, Lubbock, TX 79409, USA

3

Department of Chemical Engineering, Texas Tech University, Lubbock, TX 79409, USA

*corresponding author: [email protected]; 617-521-2775

Abstract

Surface modification of Engelhard titanosilicate (ETS-10) with silver (Ag) was carried out in efforts to promote the photocatalytic activity of ETS-10 towards the degradation of methylene blue (MB) under visible light irradiation. The core-shell heterostructure encapsulates the Ag nanoparticles, which would otherwise dislodge from the surface of ETS-10. The Ag@ETS-10 core-shell heterostructured photocatalyst was prepared by the photodeposition of Ag nanoparticles onto ETS-10 crystals to form the Ag-ETS-10 core, followed by secondary growth of ETS-10 shell using the Ag-ETS-10 as seeds. Ag@ETS-10 showed absorption in the visible light region, as well as a red shift in the UV region, compared to the unmodified ETS-10. The extent of shell growth depended on the seeding level. Increasing the seeding level from 1 wt.% to 50 wt.% resulted in a decreased mode of the particle size distribution of the products, and thus a decreased shell thickness. The Ag@ETS-10 photocatalyst grown using 50 wt.% seeding level (i.e., ~0.1 μm shell) showed 1

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higher photocatalytic activity in the photodegradation of MB under visible light irradiation (k = 0.0159 min-1) than the unmodified ETS-10 sample (k = 0.007 min-1). However, the Ag@ETS-10 photocatalyst grown using 1 wt. % seeding levels (i.e., ~ 0.8 µm shell) showed lower photocatalytic activity compared to the Ag@ETS-10 photocatalyst grown using 50 wt.% seeding level (i.e., ~ 0.1 µm shell). This was attributed to the suppression of the plasmon resonance peak when a thicker ETS-10 shell was grown around the Ag-ETS-10 core.

INTRODUCTION ETS-10 is a crystalline, zeo-type material consisting of corner sharing TiO6 octahedra linked to SiO4 tetrahedra that create a three-dimensional 12-ring pore framework [1] with pores 4.9 Å x 7.6 Å in size [2]. When coupled with the nonframework cations Na+ and K+ [2], this framework structure makes ETS-10 a promising candidate for various applications such as adsorption [3-7] and ion exchange [8]. The well-defined monoatomic semiconductor … Ti-O-Ti-O-Ti… chains within the framework give rise to a bandgap energy of 4.03 eV [2], making ETS-10 ideal for photocatalytic applications such as the photodegradation of organ