CoPt-Co hybrid supported on amino modified SiO_2 nanospheres as a high performance catalyst for hydrogen generation from ammonia borane

CoPt-Co hybrids were successfully supported on amino modified SiO₂ nanospheres by a chemical reduction method at a temperature of 278 K. The solid carrier i.e. amino modified SiO₂, provides numerous anchoring sites for the metal nanoparticles (NPs) to improve the dispersion while reducing the size of metal NPs. The supported NPs displayed a narrow particle size distribution on the SiO₂ surface with an average diameter of 12 nm. The XRD results alongside with the binary alloy phase diagram suggest that the resulted NPs are bimetallic, composed of CoPt and amorphous Co. Among the prepared materials, the solid with the specific composition of SiO₂@Pt_0.1Co_0.9 was proved to be effective catalyst for ammonia borane (AB) hydrolysis in aqueous solution. The turnover frequency (TOF) value of the supported nanocatalyst was 25.59 ${\mathrm{mol}}_{H_2}?{\min }^{?1}?{\mathrm{mol}}_M^{?1}$, almost twice as that of unsupported Pt_0.1Co_0.9 NPs while the activation energy was 37.05 kJ mol^?1. Furthermore, the SiO₂@Pt_0.1Co_0.9 composite manifested high catalytic activity even after five cycles of reuse.