Citation: Petcu, G.; Papa, F.; Anghel, E.M.; Atkinson, I.; Preda, S.; Somacescu, S.; Culita, D.C.; Baran, A.; Ciobanu, E.M.; Jecu, L.M.; et al. Effects of Aluminosilicate Gel Treatment and TiO 2 Loading on Photocatalytic Properties of Au–TiO 2 /Zeolite Y. Gels 2023, 9, 503. https://doi.org/10.3390/ gels9060503 Academic Editors: Yuesheng Li, Avinash J. Patil, Xiaojie Yang, Jun Xing and Yiwan Huang Received: 19 May 2023 Revised: 9 June 2023 Accepted: 16 June 2023 Published: 20 June 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). gels Article Effects of Aluminosilicate Gel Treatment and TiO 2 Loading on Photocatalytic Properties of Au–TiO 2 /Zeolite Y Gabriela Petcu 1, *, Florica Papa 1 , Elena Maria Anghel 1 , Irina Atkinson 1 , Silviu Preda 1 , Simona Somacescu 1 , Daniela C. Culita 1 , Adriana Baran 1 , Elena Madalina Ciobanu 1 , Luiza Maria Jecu 2 , Mariana Constantin 2 and Viorica Parvulescu 1, * 1 Institute of Physical Chemistry “Ilie Murgulescu” of the Romanian Academy, 202 Splaiul Independentei, 060021 Bucharest, Romania; manghel@icf.ro (E.M.A.); iatkinson@icf.ro (I.A.); mciobanu@icf.ro (E.M.C.) 2 National Institute for Research & Development in Chemistry and Petrochemistry-ICECHIM, Spl. Independentei 202, 060021 Bucharest, Romania * Correspondence: gpetcu@icf.ro (G.P.); vpirvulescu@icf.ro (V.P.) Abstract: The present work reports the synthesis of efficient Ti–Au/zeolite Y photocatalysts by different processing of aluminosilicate gel and studies the effect of titania content on the structural, morphological, textural, and optical properties of the materials. The best characteristics of zeolite Y were obtained by aging the synthesis gel in static conditions and mixing the precursors under magnetic stirring. Titania (5, 10, 20%) and gold (1%) species were incorporated in zeolite Y support by the post-synthesis method. The samples were characterized by X-ray diffraction, N 2 -physisorption, SEM, Raman, UV–Vis and photoluminescence spectroscopy, XPS, H 2 -TPR, and CO 2 -TPD. The photo- catalyst with the lowest TiO 2 loading shows only metallic Au on the outermost surface layer, while a higher content favors the formation of additional species such as: cluster type Au, Au 1+ , and Au 3+ . A high TiO 2 content contributes to increasing the lifetime of photogenerated charge careers, and the adsorption capacity of the pollutant. Therefore, an increase in the photocatalytic performances (evaluated in degradation of amoxicillin in water under UV and visible light) was evidenced with the titania content. The effect is more significant in visible light due to the surface plasmon resonance (SPR) effect of gold interacting with the supported titania. Keywords: aluminosilicate gel; zeolite Y; Ti–Au zeolite Y; photocatalysis; surface plasmon resonance; effect of TiO 2 loading; photodegradation; amoxicillin 1. Introduction The importance of faujasite-based catalysts has led to a growing interest in facile synthesis procedures that allow for preparing high-performance materials with improved catalytic properties. The performance of zeolites is greatly influenced by their size and shape, morphological homogeneity being desirable [1–3]. It is well known that in zeolite synthesis, the mixing of aluminate and silicate in a high pH medium led to the formation of hydrogel. This behavior was explained by the spontaneously bonding in a first stage of some aluminate ions to the silica oligomers, following multiple processes of dissolution and regeneration of the gel until the equilibrium state is reached [4]. Previous studies evidenced the importance of the aging process on gel chemistry in the synthesis of zeolite materials by controlling the nucleation and crystal growth [5]. Finding the parameters that determine the crystal morphology and size is essential in tailoring the properties of zeolites [1] which are often used as supports in obtaining photocatalysts because of their specific advantages such as structure, stability, high surface area, uniform pores, and channels with high adsorption capacity, acid-basic properties, ion exchange ability, and electric field of the framework [6–8]. TiO 2 is a widely studied semiconductor due to its well-known advantages and poten- tial application in different fields such as solar energy conversion, antibacterial treatments, Gels 2023, 9, 503. https://doi.org/10.3390/gels9060503 https://www.mdpi.com/journal/gels