Hydroxyapatite-supported cobalt(O) nanoclusters as efficient and cost-effective catalyst for hydrogen generation from the hydrolysis of both sodium borohydride and ammonia-borane

摘要

Herein, we report the preparation, characterization, and catalytic use of cobalt(O) nanoclusters supported on hydroxyapatite in the hydrolysis of both basic sodium borohydride and ammonia-borane solutions. They were prepared in situ from the reduction of cobalt(II) ions adsorbed on hydroxyapatite with sodium borohydride. Hydroxyapatite-supported cobalt(O) nanoclusters were stable enough to be isolated as solid inaterial and characterized by inductively coupled plasma optical emission spectroscopy (ICP-OES), X-ray diffraction (XRD), attenuated total reflectance infrared (ATR-iR) spectroscopy. X-ray pho-toelectron spectroscopy (XPS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) spectroscopy. They are isoiable, redispersible, highly active, and cost-effective catalysts for hydrogen generation from the hydrolysis of both sodium borohydride and ammonia-borane even at low concentrations and temperature, providing 25,600 and 7400 turnovers and maximum hydrogen generation rates of 5.0 and 2.2 L H2 min~(-1) (gCo)~(-1) by the hydrolysis of NaBH4 and H3NBH3 at 25.0±0.1 C, respectively. Hydroxyapatite-supported cobalt(O) nanoclusters provide activation energy of 53 ± 2 kJ/mol for the hydrolysis of sodium borohydride and 50 ± 2 kJ/mol for the hydrolysis of ammonia-borane.