## 1 Introduction  
Hazardous organic contaminants from many sources, such as farms and factories, are frequently found in wastewaters and can cause environmental issues [1]. Therefore, photocatalytic degradation of various organic compounds in water has been investigated in the last few decades [2]. Various materials and their composites can decompose organic dyes in water: binary oxides (e.g., TiO\({}_{2}\), ZnO, ZrO\({}_{2}\)), ternary oxides (e.g., SrTiO\({}_{3}\), LiTaO\({}_{3}\), NaTaO\({}_{3}\)), solid solutions (e.g., \(\beta\)AgAl\({}_{1-x}\)Ga\({}_{3}\)O\({}_{2}\), (AgNbO\({}_{3}\))\({}_{1-x}\)(NaNbO\({}_{3}\))\({}_{x}\)), nanocomposite materials (e.g., TiO\({}_{2}\) nanorods, ZnO nanorods, TiO\({}_{2}\)/ZnS) [3], or hybrid photocatalysts (Bi\({}_{3}\)TaO\({}_{7}\)/Ti\({}_{3}\)C\({}_{2}\), Bi\({}_{2}\)S\({}_{3}\)/Bi\({}_{2}\)O\({}_{3}\)/Bi\({}_{2}\)O\({}_{2}\)CO\({}_{3}\)) [4, 5]. Of the many different photocatalysts, TiO\({}_{2}\) has been the most widely studied and used in many applications because of its strong oxidizing ability to decompose organic pollutants superhydrophilicity, chemical stability, long durability, nontoxicity, low cost, and transparency to visible light [6]. When TiO\({}_{2}\) or another photocatalyst absorbs a photon with energy equal to or higher than the band gap energy (\(E_{g}\)), electrons (\(e^{-}\)) jump from the valence band (\(VB\)) to the conduction band (\(CB\)), and an electron-hole (\(h^{+}\)) in the valence band forms. The e\({}^{-}\) and \(h^{+}\) pair can recombine or move to the TiO\({}_{2}\) surface. These charge carriers react with the surface hydroxyl group or water and dissolved oxygen to produce hydroxyl (OH), peroxide (H\({}_{2}\)O\({}_{2}\)), and superoxide (O\({}_{2}\)\({}^{-}\)) radical anions. Later, the -OH radicals react with the organic molecules to form CO\({}_{2}\), H\({}_{2}\)O, NO\({}_{3}\)\({}^{-}\), and NH\({}_{4}\)\({}^{+}\) compounds [7]. However, the major drawbacks of TiO\({}_{2}\) as a photocatalyst are wide band gap, short recombination time of charge carriers in bulk or on the surface, and reusability if it is in powder form [8]. This limits the application of TiO\({}_{2}\) in the visible light region, affects photocatalytic efficiency, and slows down commercialization. Researchers proposed many methods to solve these problems: heterojunction formation [9], doping [10], noble metal deposition, inorganic acids modification, dye sensitization, or metal ion implantation [11]. For example, an increase in photocatalytic efficiency was observed when TiO\({}_{2}\) thin films were doped with a low amount of Cu (0.6 wt.%; \(k_{Cu}\) = 0.022 min\({}^{-1}\)), followed by Mg (0.9 wt.%; \(k_{Mg}\) = 0.019 min\({}^{-1}\)) and Ni (0.5 wt.%; \(k_{Ni}\) = 0.013 min\({}^{-1}\)) [8]. The metal nanoparticles/semiconductor heterojunctions also have great potential in high-performance photocatalysis (plasmonic photocatalysis) [12]. The benefits of metal nanoparticles/semiconductor heterojunctions emerge via metal-semiconductor junction and localized surface plasmon resonance (LSPR). The metal/semiconductor junction extends the e\({}^{-}\) and \(h^{+}\) separation time and increases the charge transfer rate. The LSPR enhances visible light response, UV light absorption, local heating effect, and reduces e\({}^{-}\) and \(h^{+}\) diffusion length, etc. [13]. Different effects can be obtained depending on the wavelength of the light. [13,14]. After UV light irradiation, only the semiconductor is excited. Metal nanoparticles act as sinks for photo-induced electrons due to the Schottky barrier [15]. It prolongs the lifespan of photoelectrons, i.e., slows down the recombination process [16]. After VIS light irradiation, LSPR occurs. Three outcomes are possible for LSPR: photon scattering, plasmon resonance energy transfer, and hot electron transfer [14]. These processes increase charge carrier concentration or, in other words, photocatalytic efficiency. After UV-VIS light irradiation, a synergetic effect of UV and VIS light occurs [17].