Hydrolytic dehydrogenation of NH3BH3 over Cu/CoOx(OH)y nanocomposite for H2 evolution

Abstract

Although a variety of noble-metal-based nanocatalysts, such as Pd, Pt, Au, Rh, and Ru, have been developed for the efficient H2 evolution from hydrolytic dehydrogenation of NH3BH3, it is extremely desirable to design and develop noble-metal-free nanomaterials as the high-efficiency nanocatalysts for H2 generation from hydrolytic dehydrogenation of NH3BH3. Herein, we first designed and synthesized a string of CoOx(OH)y colloid-stabilized Cu, Ni, Co and Fe nanoparticles (Cu/CoOx(OH)y, Ni/CoOx(OH)y, Co/CoOx(OH)y and Fe/CoOx(OH)y), by immobilization of Cu, Ni, Co or Fe nanoparticles at the surface of CoOx(OH)y colloid, for the efficient H2 evolution from hydrolytic dehydrogenation of NH3BH3 at 30 °C. The optional Cu/CoOx(OH)y nanohybrid exhibits the super-high catalytic property, with the highest TOF of 67.5 mol(H2)·molCu-1·min−1, in the H2 evolution from hydrolytic dehydrogenation of NH3BH3 at 30 °C. More Interestingly, the TOF of Cu/CoOx(OH)y nanohybrid catalyzed hydrolytic dehydrogenation of NH3BH3 reaches to 630.58 mol(H2)·molCu-1·min−1 (2789 mL(H2)·gcat-1·min−1) under 0.3 mol/L NaOH, which exceeds all or almost all non-noble metal nanocatalysts, even some noble metal nanocatalysts. The comparison of other common supports, including Fe(OH)3, Ni(OH)2 and Cu(OH)2, has highlighted the vital role of CoOx(OH)y in NH3BH3 hydrolytic dehydrogenation. A large KIE of 2.7 with D2O has illustrated that the oxygen-hydrogen bond cleavage of water was the rate-determining step in the hydrolytic dehydrogenation of NH3BH3. This work not only provides a new explication for the cost-effective design and synthesis of magnetic nanomaterials, but also offers a high-efficiency noble-metal-free nanocatalyst for H2 evolution from hydrolytic dehydrogenation of NH3BH3.