Layered Perovskite La\({}_{2}\)Ti\({}_{2}\)O\({}_{7}\) Obtained by Sol-Gel Method with Photocatalytic Activity  
[PERSON]  
1 \"[PERSON]\" Institute of Physical Chemistry of the Romanian Academy, 202 Spliaul Independentie, 060021 Bucharest, Romania 12  
The La\({}_{2}\)Ti\({}_{2}\)O\({}_{7}\) phase crystallizes in the monoclinic system (space group P2\({}_{1}\)) and contains four formula units per unit cell. Its structure is composed of four distorted perovskite units aligned perpendicularly on infinite layers of TiO\({}_{6}\) octahedra [14]. This structural anisotropy results in anisotropic dielectric, electrical, and mechanical properties [12]. La\({}_{2}\)Ti\({}_{2}\)O\({}_{7}\) is a multifunctional oxide recognized for several notable attributes:  
* Piezoelectric/ferroelectric properties: exhibits a high Curie temperature [15; 16]. * Superior thermal stability: possesses good electron mobility due to ions on A sites and high conductivity [16]. * Wide bandgap (\(\sim\)3.8 eV): capable of generating photoelectrons with a high reduction potential [17; 18]. * Good resistance to ionizing radiation [19]. * Layered structure: favorable for the separation and transfer of photogenerated electron-hole pairs, as well as separating oxidation from reduction reaction sites [18]. * Host matrix: can host other lanthanides to create new phosphors with conventional luminescence under UV excitation [15]. * Photocatalytic capabilities: particularly for hydrogen generation via water splitting [20; 21] and for the degradation of volatile organic compounds (VOCs) [22]. * However, its large band gap limits photocatalytic efficiency under visible light [16], and its low solar light utilization and easy recombination of photogenerated charge carriers hinder achieving the commercial application target of 5-10% solar hydrogen conversion efficiency (STH) [9]. La\({}_{2}\)Ti\({}_{2}\)O\({}_{7}\) is a material with increasing applications in a variety of domains, from catalysis and photocatalysis [23; 24; 25] to dielectrics [26], superconductors [27], and luminescent materials [19]. Numerous environmental issues could be resolved by creating stable, inexpensive, and highly efficient photocatalysts that utilize solar energy [28]. Applications of La\({}_{2}\)Ti\({}_{2}\)O\({}_{7}\) oxide include water-splitting [29]; co-catalyzation with metals [30; 31]; the photocatalytic degradation of organic pollutants and colorants [13; 15; 16; 32; 33]; the oxidation of methanol [34; 35], ethanol [36; 37], and phenol [14; 38]; and the photodegradation of antibiotics [21; 39]. However, the degree of crystallinity and the material's exchange surface have a significant impact on the photocatalytic efficiency. In recent years, scientific research has seen a great deal of interest regarding the optimization of synthetic parameters to control the size of crystallites and their crystallinity, specifically through the following: (i) the use of polymer precursors for controlling porosity [40], (ii) the type of precursors used [41; 42], and (iii) the diversification of synthesis processes. Various techniques have been used to synthesize La\({}_{2}\)Ti\({}_{2}\)O\({}_{7}\), including solid-state processing [43], co-precipitation of hydroxides [44], urea precipitation [45], hydrothermal synthesis [46], high-temperature decomposition of metal-organic precursors [47], thermal decomposition of nitrates [48], liquid mix techniques [49], the hydrothermal route [50; 51], microwave-assisted synthesis [52], and the sol-gel route [53; 54; 55]. While these methods offer the advantage of smaller particle sizes over the solid-state approach, most of them typically come with the drawbacks of extended heating times and multi-step synthetic procedures. The sol-gel process has attracted attention as an interesting method for creating nanocomposites [56; 57].