# Highly Active under VIS Light M/TiO\({}_{2}\) Photocatalysts Prepared by Single-Step Synthesis
## 1 Introduction
In the same study, the effect of Ag concentration was also determined through experimentation [31]. The catalytic behavior of thin Ag/TiO\({}_{2}\) films under UV light was the subject of a study whose conclusion was that the addition of Ag to the films leads to a significant improvement in the degradation efficiency versus a pure TiO\({}_{2}\) catalyst [32]. The use of Cu and Ag as co-dopants to TiO\({}_{2}\) substrate has been investigated, resulting in the observation that there is an optimum mixing ratio of doping metals (1 wt% Ag: 2 wt% Cu). The co-catalysts' photocatalytic degradation of MB and salicylic acid under visible irradiation was approximately 2-4 times higher than their monometallic counterparts, as the co-catalysts exhibited better synergistic effect, increased lifetime of the generated charge carriers, and active sites on the co-catalyst surface. The dual role of Ag and Cu metals resulted in enhanced photocatalytic performance in co-catalytic systems due to the combined functional behavior of deposited metals and improved interfacial charge transfer process [33]. Moreover, Ni(OH)\({}_{2}\)-based co-catalysts have attracted increasing research interest in the field of solar-to-fuel conversion and, in particular, photocatalytic H\({}_{2}\) production and CO\({}_{2}\) reduction [34]. Last but not least, cobalt sulfide-based composites have also exhibited promising results in the field of solar fuel conversion and are being considered good candidates in photocatalytic hydrogen production, carbon dioxide reduction, nitrogen fixation, and photocatalytic degradation of pollutants due to their low cost and easy way of synthesis as well as their diverse structures [35]. Many efforts have been made to develop catalysts to improve the photocatalytic degradation of MB, indicating that they would be capable of being used on several other organic compounds to catalyze their photodegradation. Metals such as Cu and Ag have been focused on recently, with a variety of preparation techniques being studied. A common point in most of the performed research is that there is an optimum amount of dopant concentration, meaning that at first, the increase in the metal concentration has positive effects up to a certain amount that has been added, while the excess amount of metal in the catalyst negatively impacts the photodegradation efficiency of the catalyst. Taking into consideration the studies that have been performed and the results that have been obtained by them, the current study aims to evaluate and optimize the single-step synthetic route for the preparation of Cu/TiO\({}_{2}\), Ag/TiO\({}_{2}\), and Cu/Ag/TiO\({}_{2}\) photocatalysts and assess their efficiency in degrading methylene blue dye. The importance of a single-step synthesis is rooted in its simplicity, as well as the time efficiency and cost-effectiveness, all of which are vital parameters regarding the sustainability of the method. The photocatalytic reaction took place at room temperature (25 \({}^{\circ}\)C) while targeting a relatively high initial MB concentration (250 ppm) for the lab-scale experiment. Furthermore, a parametric optimization of the materials was studied with respect to their effect on the photodegradation efficiency.