Maximizing Metal-Support Interactions in Pt/Co₃O₄ Nanocages to Simultaneously Boost Hydrogen Production Activity and...

Catalytic hydrolysis of ammonia borane (AB) provides an effective way to generate pure H₂ at ambient temperature for fuel cells. Pt-based catalysts usually exhibit great initial activity toward this reaction but deactivate quickly. Here, we report that the metal-support interactions in Pt/Co₃O₄ nanocages can simultaneously accelerate the H₂ generation and enhance the catalyst's stability. The Pt/Co₃O₄ catalyst is made for the first time by embedding Pt clusters (∼1.2 nm) in a high-surface-area Co₃O₄ nanocage to maximize the metal-support interface. The turnover frequency of the Pt/Co₃O₄ catalyst is about nine times higher than that of commercial Pt/C and outperforms almost all other Pt-based catalysts. X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, in situ spectroscopy, and density functional theory calculations suggest that the Co₃O₄ nanocages with rich oxygen vacancies facilitate the adsorption and dissociation of H₂O to give electropositive H (H^δ+), while the in situ embedded Pt clusters can accelerate the formation of electronegative H (H^δ-) from AB. Subsequently, the H^δ+ and H^δ- spill over to the abundant interfacial sites and bond into H₂. In addition to this dual-function synergy effect, the strong metal-support electronic interactions between Co₃O₄ and Pt benefit the desorption of poisonous B-containing byproducts from Pt sites. This effect together with cluster anchoring leads to a fivefold enhancement in durability compared to commercial Pt/C. The metal-support interactions revealed in this study provide more options for catalyst design toward facile H₂ production from chemical hydrogen storage materials.