## 2 Synthesis  
The synthesis route for BCPs has great influence on photocatalytic performance. Various efficient methods and approaches have been reported for the synthesis of BCPs (summarized in Table 1), including sol-gel [28; 29; 30; 31; 32; 33; 34; 43], hydrothermal/solvothermal [36; 38; 39; 45; 46; 47; 48; 49; 50; 51; 52; 53], ultrasound [40; 54; 55; 56; 57; 58], calcination [56; 57; 58; 34; 58] and in situ methods [59; 35], etc. Figure 1: Carbonaceous materials and the mechanisms of BCPs on the treatment of wastewater. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**BCPs** & **Biomass** & **Pollutants** & **Synthesis Route** & **Working Conditions** & **Performance** & **Refs.** \\ \hline BC-TiO\({}_{2}\) & \multirow{2}{*}{Coomout shell} & Reactive Boilliant Blue & \multirow{2}{*}{Sol-gel} & \(\{\text{[XX-I]}=30\,\text{mg}\,\text{L}^{-1}\),} & 99.71\% (pH = 1, 60 min) & \multirow{2}{*}{[28]} \\  & & KX-R & & & & \\  & & & & & & \\  & & & & & & \\  & & & & & & \\ BC-TiO\({}_{2}\) & \multirow{2}{*}{Salvinia molesta (SM)} & Acid Orange 7 (AO7) & \multirow{2}{*}{Mechanical mixing} & \(\{\text{[BCr]}=0.25\,\text{g}\,\text{L}^{-1}\)} & 57.6\% (180 min) & \multirow{2}{*}{[29]} \\  & & & & & \(\text{[SMX]}=10\,\text{mg}\,\text{L}^{-1}\), & \\ BC-TiO\({}_{2}\) & \multirow{2}{*}{Reed straw (RS)} & Salvanthownacle (SMQ) & \multirow{2}{*}{Sol-gel} & \(\{\text{[BCr]}=1.25\,\text{g}\,\text{L}^{-1}\)} & 91.27\% (180 min) & \multirow{2}{*}{[30]} \\  & & & & & \(\text{[VIW]}=10\) & \\ BC-TiO\({}_{2}\) & \multirow{2}{*}{Ramie char} & \multirow{2}{*}{Safarinine T (ST)} & \multirow{2}{*}{Modified sol-gel} & \(\{\text{[ST]}=500\,\text{mg}\,\text{L}^{-1}\)} & \multirow{2}{*}{226.7 mg s\({}^{-1}\) (120 min)} & \multirow{2}{*}{[31]} \\  & & & & & \(\text{[SOX]}=10\,\text{mg}\,\text{L}^{-1}\), & \\ BC-TiO\({}_{2}\) & \multirow{2}{*}{Corn cob (CC)} & \multirow{2}{*}{SMX} & Sol-gel & \(\{\text{[BCr]}=5\,\text{g}\,\text{L}^{-1}\)} & \multirow{2}{*}{\(\text{[SO min]}\)} & \multirow{2}{*}{[22]} \\  & & & & & \(\text{[VO]}=10\,\text{mg}\,\text{L}^{-1}\), & \\ BC-TiO\({}_{2}\) & \multirow{2}{*}{Sugarance baggase} & Methyl orange (MO) & \multirow{2}{*}{Sol-gel} & \(\{\text{[BCr]}=1.2\,\text{g}\,\text{L}^{-1}\)} & \multirow{2}{*}{95.0\% (300 min)} & \multirow{2}{*}{[43]} \\  & & & & & \(\text{[SMX]}=10\,\text{mg}\,\text{L}^{-1}\) & \\ BC-Zr\({}_{2}\)/TiO\({}_{2}\) & \multirow{2}{*}{Reed straw} & \multirow{2}{*}{SMX} & Modified sol-gel & \(\{\text{[BCr]}=1.25\,\text{g}\,\text{L}^{-1}\)} & \multirow{2}{*}{81.21\% (180 min)} & \multirow{2}{*}{[44]} \\  & & & & & \(\text{[OC]}=50\,\text{mg}\,\text{L}^{-1}\) & \\ BC-ZnO & \multirow{2}{*}{Waste biomass} & \multirow{2}{*}{Orange G dye (OG)} & \multirow{2}{*}{Hydrothermal} & \(\{\text{[BCr]}=1.2\,\text{g}\,\text{L}^{-1}\)} & \multirow{2}{*}{88.4\% (Visible light)} & \multirow{2}{*}{[36]} \\  & & & & & UV and visible light & 94.1\% (UV light) & \\ BC-TiO\({}_{2}\) & \multirow{2}{*}{Wahut shells} & \multirow{2}{*}{MO} & \multirow{2}{*}{Hydrothermal} & \(\{\text{[MO]}=20\,\text{mg}\,\text{L}^{-1}\)} & \multirow{2}{*}{92.45\% (decortization,}\) & \multirow{2}{*}{[30]} \\  & & & & & \(\text{[SO]}=0.25\,\text{g}\,\text{L}^{-1}\) & \\  & & & & & UV light & 150 min \\ BC-SiO\({}_{2}\)/Co/\({}_{3}\) & \multirow{2}{*}{Prunus ducks} & \multirow{2}{*}{Paraquat (YQT)} & \multirow{2}{*}{Hydrothermal} & \(\{\text{[BCr]}=0.2\,\text{pg}\,\text{L}^{-1}\)} & \multirow{2}{*}{90 min} \\  & & & & & Visible light and sunlight & 92.1\% (Solar light, \\ BC-TiO\({}_{2}\) & \multirow{2}{*}{Hazelutut shell (HS)} & \multirow{2}{*}{Methylene blue (MB)} & \multirow{2}{*}{Hydrothermal} & \(\{\text{[MB]}=10\,\text{ppm}\),} & \multirow{2}{*}{96.97\% (HS-TiO\({}_{2}\),}\) \\  & & & & & \(\text{[RV]}=1\,\text{g}\,\text{L}^{-1}\) & \\ BC-TiO\({}_{2}\) & \multirow{2}{*}{and olive residue (OR)} & \multirow{2}{*}{Methylene blue (MB)} & \multirow{2}{*}{Sol-gel} & \(\{\text{[BCr]}=1.2\,\text{g}\,\text{L}^{-1}\)} & \multirow{2}{*}{420 min} \\  & & & & & Visible light & 420 min) \\ \hline \hline \end{tabular}
\end{table}