Controlled Synthesis of Copper Sulfide Nanoparticles in Oxygen‐Deficient Conditions Using Flame Spray Pyrolysis (FSP) and Its Potential Application

The objective of this study is to investigate the influence of various process parameters, such as the fuel-to-oxygen ratio, precursor flow rate, co-flow rate, and different metal-to-sulfur ratios on the properties of metal sulfide particles synthesized via flame spray pyrolysis (FSP). The particle size increases with increasing dispersion oxygen flow and copper sulfide is obtained only when the fuel-to-oxygen ratio is equal to or higher than 1.5. The temperature of the flame rises with an increasing precursor flow rate and copper sulfide is formed at a precursor flow rate of 5 mL min^-1 or lower, while contamination occurs above 5 mL min^-1. A Co-flow rate above 100 L min^-1 is required to cool the aerosol stream before deposition on the filter. A pure copper sulfide phase is produced when sulfur is more than 5 times in molar ratio compared to Cu in the liquid solution and particle size decreases with increasing sulfur concentration. This research will contribute to a better understanding of the fundamental formation process of metal sulfides under oxygen-lean gas-phase conditions and serve as a milestone in optimizing synthesis parameters for various applications.