Catalytic modification in dehydrogenation properties of KSiH3

Abstract

A number of known catalysts, which have been proven to be very effective for several hydrogen species, were studied in order to determine their effects on the hydrogen ab/desorption properties of KSiH₃. Among all the catalysts used in this work, mesoporous Nb₂O₅ is found to be quite effective, with a reduction in activation energy from 142 kJ mol⁻¹ for pristine KSi to 63 kJ mol⁻¹ for mesoporous-Nb₂O₅-added KSi, thus allowing desorption to start at 100–120 °C. Any disproportionation is not observed in the controlled hydrogenation process. The mechanism for this improvement is also proposed in detail. The kinetic modifications on the ab/desorption properties of KSiH₃ provide an alternative to the well-known family of heavy BCC alloys which are capable of working in the same temperature range but with a lower gravimetric hydrogen content, almost half of the KSi system.