H2 generation from two-step thermochemical water-splitting reaction using sol-gel derived SnxFeyOz

Abstract

H2 has a great potential to replace fossil fuels and contribute to clean energy by reducing the environmental carbon foot-print. This study reports H2 generation from a thermochemical water-splitting reaction using sol-gel derived SnxFeyOz powders. The sol-gel synthesis involved the addition of SnCl2 · 2H2O and FeCl2 · 4H2O in ethanol followed by gelation using propylene oxide. As-synthesized gels were aged, dried, and heated rapidly upto different temperatures and quenched in air or N2 environment. The calcined powders were characterized using powder x-ray diffraction, BET surface area analyzer, and scanning electron microscopy (SEM). Calcination temperature and environment were found to have a significant effect on phase composition and specific surface area (SSA). The calcined SnxFeyOz powders were placed in a tubular Inconel reactor and four consecutive thermochemical cycles were performed. Water-splitting and regeneration steps were carried out at 900 °C and 1100 °C, respectively. The powder calcined in N2 environment showed a mixed phase composition containing Sn0.4Fe2.6O4 and SnO2 and it generated an average of 1.88 ml of H2 g−1 cycle−1.