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

作者：Zhang, Qing; Xu, Fuhua; Huang, Wenkai; Wang, Yanlan^*; Liu, Xiang^*

来源：Fuel, 2023, 337: 126870.

DOI：10.1016/j.fuel.2022.126870

• H-2 evolution
• NH3BH3
• Hydrolytic dehydrogenation
• Cu/CoOx(OH)(y)
• Mechanism

Although a variety of noble-metal-based nanocatalysts, such as Pd, Pt, Au, Rh, and Ru, have been developed for the efficient H-2 evolution from hydrolytic dehydrogenation of NH3BH3, it is extremely desirable to design and develop noble-metal-free nanomaterials as the high-efficiency nanocatalysts for H-2 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 H-2 evolution from hydrolytic dehydrogenation of NH3BH3 at 30 degrees C. The optional Cu/CoOx(OH)(y) nanohybrid exhibits the super-high catalytic property, with the highest TOF of 67.5 mol(H-2)center dot mol(Cu)(-1)center dot min(-1), in the H-2 evolution from hydrolytic dehydrogenation of NH3BH3 at 30 degrees C. More Interestingly, the TOF of Cu/CoOx(OH)y nanohybrid catalyzed hydrolytic dehydrogenation of NH3BH3 reaches to 630.58 mol(H-2)center dot mol(Cu)(-1)center dot min(-1) (2789 mL(H2)center dot gcat(-1)center dot 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 H-2 evolution from hydrolytic dehydrogenation of NH3BH3.