## 3 Synthesis and Characterization of the Nanoparticles  
### Synthesis and Characterization of Bismuth Sulphide  
The bismuth sulphide was prepared from the thermal decomposition of the bismuth (III) dithiocarbamate complex. The first stage involved the preparation of the dithiol \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Accession** & **Isolate Name** & **Accession** & **Blastn, Closest** & **Relative** & **Similarity \%** & **E Value** \\
**Code** & **Number** & **Relative** & **Accession** & **Simularity \%** & **E Value** \\ \hline AD1 & _Bipolars zeicola strain 1_ & OP536177 & _Bipolars zeicola_ & MK841439 & 99.81 & 0.0 \\ AD6 & _Pbom herbarum strain 1_ & OP536178 & _Pbom herbarum_ & MT420621 & 100 & 0.0 \\ AH1 & _Epicoccum nigrsimulate_ & OP536185 & _Epicoccum nigrum_ & MT528797 & 100 & 0.0 \\ BD5A & _Alternaria alternata strain 2_ & OP536192 & _Alternaria alternata_ & MN249500 & 100 & 0.0 \\ BD2 & _Fusarium brachygibosum_ & OP536195 & _Fusarium brachygibosum_ & KY024400 & 100 & 0.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: 16 s rRNA gene sequence-based identification of the isolates and their accession numbers. carbamate complex of bismuth. This stage started with the reaction of equal moles of p-tolualdehyde and 4-ethylaniline dissolved in a flask by using ethanol as a solvent. The content of the flask was stirred for 3 h under ice, and the solvent was evaporated to obtain an oil-like product. The oily product obtained was dissolved in a solution containing 1:1 methanol and dichloromethane. Then, 13.8 mmol of sodium borohydride was introduced into the flask. This was first stirred for 2 h under ice, immediately followed by 24 h stirring at room temperature. After this, the solvent was evaporated by raising the temperature to 40 \({}^{\circ}\)C. The product obtained at this stage was washed with distilled water and extracted with dichloromethane via the use of a separating funnel. The organic phase was evaporated by stirring at 40 \({}^{\circ}\)C again to obtain a light-yellow oil. The oil obtained (4 mmol) was dissolved in ethanol in a clean flask and 4 mmol of carbon disulphide was added. The pH of the content of the flask was altered by adding 10 mL of NH\({}_{4}\)OH. The whole content was stirred for 2 h 15 min then 1.67 mmol of hydrated bismuth nitrate was introduced and stirred for 12 h. The resultant creamy solution was filtered under pressure and left to dry to obtain the bismuth (III) dithiocarbamate. The second stage involved the thermal decomposition of the dithiocarbamate. A solvothermal reaction was employed under an atmosphere of nitrogen. Briefly, 1.00 g of the dithiocarbamate complex was introduced into a 3-necked round bottom flask and 20 mL of oleylamine was added. The mixture was steadily heated until it reached 180 \({}^{\circ}\)C and it was maintained at this temperature for 1 h. After the reaction was complete, the flask was allowed to cool to room temperature, and then the product obtained was washed by centrifugation with ethanol and toluene. The pure product was dried in an oven set at 80 \({}^{\circ}\)C for 6 h. This final product was kept for characterization. The entire synthetic processes have been summarized in Figure 1.  
Figure 1: Synthesis of bismuth sulphide and graphitic carbon nitride used for the antifungal treatment of foliar fungi of maize. One of the most powerful and non-destructive tools for the structural characterization of materials is X-ray diffraction (XRD) [32]. The structural identification of bismuth sulphide was carried out in the range of 0\({}^{\circ}\) to 80\({}^{\circ}\) 2\(\theta\) angle. As shown in Figure 2, all the peaks are the characteristic peaks of the orthorhombic lattice structure of bismuth sulphide, having a space group of _Pbmm_ (62) (JCPDS card 17-0320) [33]. Prominent among these peaks are (130), (211) and (221) at 24.9\({}^{\circ}\), 28.6\({}^{\circ}\) and 31.8\({}^{\circ}\), respectively. The pattern obtained perfectly matched that of an earlier report [34].