MOF-Derived Co-Based Catalyst Supported on TiO2 for Hydrogen Generation from Ammonia Borane

Ammonia borane (AB) is an ideal chemical hydrogen storage material owing to its high gravimetric and volumetric hydrogen capacities. However, the practical application through hydrolysis calls for catalysts that are efficient, stable, and low-cost. In this work, a CoxC/TiO2catalyst was synthesized by pyrolyzing a Co-MOF precursor supported on TiO2. The TiO2effectively dispersed the precursor and suppressed particle agglomeration, yielding highly dispersed Co nanoparticles that were uniformly embedded on the support within the carbon matrix after pyrolysis. The catalyst achieved a specific reaction rate of 10.7 molH2·molCo−1·min−1, which was approximately 9.7 times higher than that of the support-free CoC (specific reaction rate = 1.1 molH2·molCo−1·min−1), and significantly outperformed counterparts supported on SiO2or Al2O3. The catalyst also exhibited a low activation energy of 33.18 kJ·mol−1and retained about 60% of its initial activity after five cycles. XRD, SEM, and TEM characterizations confirmed the high dispersion of Co species and the morphological evolution induced by TiO2. The enhanced performance was attributed to the synergistic effect between Co active sites and the reducible TiO2via hydrogen spillover. Control experiments using Ni-based catalysts further verified that only reducible supports such as TiO2and ZrO2substantially enhanced activity, confirming the generality of the hydrogen spillover mechanism. This study provided a facile and effective strategy for developing high-performance, non-noble metal catalysts for chemical hydrogen storage.