ZIF-8 decorated FeMo nanoparticles: H2 Production from the catalytic hydrolysis of ammonia-borane

Abstract

Ammonia-Borane (AB) is considered a promising solid hydrogen storage material due to its high hydrogen content (19.6 wt%) and its use for safe hydrogen transport. The most effective way to produce H₂ from AB is to perform the hydrolysis reaction in the presence of a suitable catalyst. In this study, Fe_0.2Mo_0.8/ZIF-8 nanocatalyst was synthesized in two steps: (i) synthesis by following the colloidal synthesis technique by thermal decomposition of Mo(CO)₆ and Fe(acac)₃ in the presence of OM and ODE at high temperatures, and (ii) the resulting colloidal Fe_0.2Mo_0.8 NPs were decorated into ZIF-8. The as-prepared Fe_0.2Mo_0.8/ZIF-8 catalyst was identified using advanced characterization techniques such as ICP-OES, P-XRD, SEM, SEM–EDX, TEM, TEM-EDX, XPS, and BET. The catalytic activities of the Fe_0.2Mo_0.8/ZIF-8 catalyst in the hydrolysis of AB were investigated in different parameters (temperature, catalyst [Fe_0.2Mo_0.8] and substrate [H₃NBH₃] concentration, and recyclability). The results show that high crystallinity Fe_0.2Mo_0.8 NPs with a uniform 1.31 ± 0.13 nm distribution were formed on the ZIF-8 surface. Fe_0.2Mo_0.8/ZIF-8 catalyst provides a maximum H₂ generation rate of 184.2 mLH₂ (g catalyst)⁻¹ (min)⁻¹ at 343 K. This uniquely cost-effective, active and durable Fe_0.2Mo_0.8/ZIF-8 catalyst has strong potential for H₂-based fuel cell (PEM: Proton Exchange Membrane) applications where AB is a suitable H₂ carrier.

Highlights

• FeMo NPs were synthesized by a colloidal synthesis method and decorated into ZIF-8.
• FeMo/ZIF-8 catalyst is an active catalyst in the hydrolysis of AB.
• FeMo/ZIF-8 catalyst showed an initial TOF value of 449.85 mol(H₂)·molFe_0.2Mo_0.8⁻¹·h⁻¹ in the AB hydrolysis at 338 K.