Photo Electrocatalytic Water Splitting Using Sn Doped In<sub>2</sub>S<sub>3</sub> Homologous Series Synthesized in Oxygen Deficient Flame
Suman Pokhrel, Jakob Stahl, Lizhuo Wang, Rui Tang, Haoyue Sun, Malte Schalk, Marco Schowalter, Andreas Rosenauer, Jun Huang, Johannes Kiefer, Johannes Birkenstock, Lutz Mädler
Abstract
Abstract The innovative development of reactive‐spray systems for gas‐phase production of metal sulfides are potential materials for next‐generation technologies. These flame‐synthesized sulfides (doped, functionalized, and heterogeneously mixed derivatives) hold significant potential as photocatalysts for water splitting. The knowledge acquired from nonaqueous precursor‐solvent and high‐temperature aerosol chemistries, optimal process parameters are established to generate In 2‐(4/3)x Sn x S 3 , solid‐solutions. The thermally driven reducing gas‐phase reactions are controlled through fuel/oxygen ratio. Particles characterizations (X‐ray diffraction, transmission electron microscopy (TEM) and imaging) revealed structural stability and crystallinity. The In 2‐(4/3)x Sn x S 3 , at higher Sn doping had enhanced photoexcitation. Donor‐acceptor levels within the material facilitated electron‐hole pair trapping, crucial for redox reactions. With suitable band gap energies for water oxidation (1.9‐1.1 eV) closely matched flat band potentials (4.38‐4.67 eV) for redox reactions. The powder characterization showed 8% In 2 O 3 in InSn 0.75 S 3 after photocatalysis due to S‐degradation in the initial light “on/off cycles”. The pioneering process of employing oxygen‐deficient reducing flame enabled a series of photo‐catalytically active metal sulfide nanoparticles with work function energies in the range of 5.19‐5.37 eV. This synthesis strategy holds the potential for impactful advancements in both industry and R&D, addressing the urgent need for new materials capable of inducing water oxidation under visible light.