## 4 Conclusions  
The development of composites produced by combining iron oxide urchins (FeO\(\times\)) with g-C\({}_{3}\)N\({}_{4}\) following two different procedures (FeO\(\times\)/g-C\({}_{3}\)N\({}_{4}\))\(in\) and (FeO\(\times\)/g-C\({}_{3}\)N\({}_{4}\))\(ex\) was reported along with its application in the photocatalytic degradation of ciprofloxacin pharmaceuticals. The PLD procedure to obtain annealed hematite iron urchins followed by the drop-casting of the melamine precursor to thermally condense the g-C\({}_{3}\)N\({}_{4}\) (FeO\(\times\)/g-C\({}_{3}\)N\({}_{4}\))\(in\) composite thin film evolved into to a petal-like morphology with a high surface area featuring good absorption in the visible range (\(<\)600 nm). This composite material exhibits an improved photocatalytic performance when compared to the single components, with the optimal condition for ciprofloxacin degradation (from 20 to nearly 60%) observed under the photo-Fenton condition. These results are compatible with a heterojunction effect in the \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Ref** & **Catalyst** & \begin{tabular}{c} **CIP** \\ **Concentration** \\ **(ppm)** \\ \end{tabular} & \begin{tabular}{c} **Tested** \\ **Volume (mL)** \\ \end{tabular} & \begin{tabular}{c} **Experimental** \\ **Time (min)** \\ \end{tabular} & \
\begin{tabular}{c} **Illumination** \\ **Source** \\ \end{tabular} &
\begin{tabular}{c} **Removal** \\ **Yield** \\ \end{tabular} \\ \hline
[92] & \
\begin{tabular}{c} N,S- \\ CQDs/Bi\({}_{2}\)MoO\({}_{6}\)@TiO\({}_{2}\) \\ \end{tabular} & 20 & 15 & 270 &
\begin{tabular}{c} Visible light ca. \\ 200 mW/cm\({}^{2}\) \\ \end{tabular} & 90\% \\ \hline
[93] & FTO/BaTiO\({}_{3}\)/SnO\({}_{2}\) & 5 & 75 & 180 &
\begin{tabular}{c} 100 W Xe lamp + \\ Ultrasound \\ 24 KHz \\ \end{tabular} & 60\% \\ \hline
[94] & Bi\({}_{2}\)MoO\({}_{6}\)@Bi\({}_{2}\)MoO\({}_{6-x}\) & 20 & 100 & 150 &
\begin{tabular}{c} 6.2 W LEDs \\ between 400 and \\ 700 nm \\ \end{tabular} & 95\% \\ \hline
[95] & TiO\({}_{2}\) MOCVD & 20 & 100 & 480 & UV LED 365 nm & 100\% \\ \hline
[96] &
\begin{tabular}{c} (nc-TiO\({}_{2}\)) from \\ Degussa P25 \\ \end{tabular} & 10 & 100 & 600 & UV lamp 276 nm & 100\% \\ \hline
[97] & \
\begin{tabular}{c} TiO\({}_{2}\) \\ films grown \\ electrochemically \\ \end{tabular} & 40 & 190 & 180 &
\begin{tabular}{c} UV lamp \\ (100–280 nm) \\ \end{tabular} & 70\% \\ \hline
[98] & Ag\({}_{2}\)MoO\({}_{4}\) & 20 & 100 & 40 &
\begin{tabular}{c} UV lamp \\ (200–400 nm) \\ \end{tabular} & 90\% \\ \hline
[99] & CeO\({}_{2}\)/CuO/ZnO/Zn & 10 & 100 & 120 & \begin{tabular}{c} Mercury lamp \\ 120 W—UV light \\ \end{tabular} & 70\% \\ \hline This work & \
\begin{tabular}{c} (FeO\(\times\)/g-C\({}_{3}\)N\({}_{4}\))\(in\) + \\ H\({}_{2}\)O\({}_{2}\) (\(5\times 10^{-4}\) M) \\ \end{tabular} & 10 & 50 & 180 &
\begin{tabular}{c} Visible Halogen \\ lamps, 225 W \\ \end{tabular} & 60\% \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Comparison for CIP removal with photocatalysts. Figure 15: Schematic showing the (FeO\(\times\)/g-C\({}_{3}\)N\({}_{4}\))\(in\) photocatalyst degradation mechanism (**a**) without H\({}_{2}\)O\({}_{2}\) and (**b**) with H\({}_{2}\)O\({}_{2}\). composite, likely of the Z-scheme type. The advantages with (FeOx/g-C\({}_{3}\)N\({}_{4}\))_in_ rely on the mechanical stability of the coating on the glass surface, which allows us to overcome the problems related to the use of nanoparticles in suspension. The research presented in this paper will be further developed as we consider the reported results as a significant starting point for obtaining a Z-scheme strategy specifically for thin-films. Indeed, further activities aimed at elucidating the working mechanism of these composites under light are ongoing.