GREEN RUST-BASED CATALYSTS FOR AMMONIA BORANE DEHYDROGENATION

抄録

Green rust (GR), a Fe²⁺/Fe³⁺-layered double hydroxide (LDH), was thought to be extremely unstable toward oxidation and thus less well studied as catalysts and their supports than many other LDHs. Here, the modification of a [Fe²⁺–Fe³⁺] mixed valent iron hydroxide, that we term GR, with Cu species and application of the Cu-modified GR as the catalyst for the hydrolysis of ammonia borane (AB) are described. From spectroscopic and microscopic analyses, the Cu-modified GR was composed of plate-like GR particles decorated with Cu₂O clusters and nanoparticles on the particles’ surfaces and edges. The Cu-modified GR, synthesized via the modification of ball-milled GR with Cu₂O species, exhibited an excellent H₂ evolution rate and amount at room temperature under solar simulator irradiation that was faster and larger, respectively, than Pt nanoparticle-supported and Cu-modified TiO₂. Control catalytic tests without solar simulator irradiation and an action spectrum study suggested that the Cu-modified GR showed light-assisted catalysis toward AB hydrolysis thanks to Cu₂O modifiers.