Enhanced hydrogen generation by reverse spillover effects over bicomponent catalysts

The contribution of the reverse spillover effect to hydrogen generation reactions is still controversial. Herein, the promotion functions for reverse spillover in the ammonia borane hydrolysis reaction are proven by constructing a spatially separated NiO/Al₂O₃/Pt bicomponent catalyst via atomic layer deposition and performing in situ quick X-ray absorption near-edge structure (XANES) characterization. For the NiO/Al₂O₃/Pt catalyst, NiO and Pt nanoparticles are attached to the outer and inner surfaces of Al₂O₃ nanotubes, respectively. In situ XANES results reveal that for ammonia borane hydrolysis, the H species generated at NiO sites spill across the support to the Pt sites reversely. The reverse spillover effects account for enhanced H₂ generation rates for NiO/Al₂O₃/Pt. For the CoO_x/Al₂O₃/Pt and NiO/TiO₂/Pt catalysts, reverse spillover effects are also confirmed. We believe that an in-depth understanding of the reverse effects will be helpful to clarify the catalytic mechanisms and provide a guide for designing highly efficient catalysts for hydrogen generation reactions.