Chemically stable TMOx@Ti-MgO (TM = Mn and Cu) catalyst enhanced De/hydrogenation kinetics of Mg/MgH2

Abstract

Ti-based catalysts have been identified to be efficient in enhancing hydrogenation and dehydrogenation (de/hydrogenation) kinetics of Mg/MgH₂. However, their catalytic activity is constrained by the strong Ti‒H bond and chemical instability. Herein, we demonstrate that TMO_x@Ti-MgO (TM = Mn and Cu) composite catalysts can simultaneously enhance hydrogen dissociation, diffusion and nucleation processes. MgH₂ catalyzed by TMO_x@Ti-MgO released 6.03−6.14 wt. % H₂ within 5 min at 280 °C and 0.89−1.12 wt. % H₂ within 60 min at 180 °C. The partially oxidized Ti²⁺ and Ti³⁺ states are stabilized in MgO lattice, accelerating hydrogen adsorption, dissociation and diffusion processes. The TMO_x, additionally, serve as the active center for nucleation, further improving de/hydrogenation reactions. The TMO_x@Ti-MgO catalysts are characterized by high chemical stability, realizing improved cycle properties. These findings suggest a new approach to achieving controllable Catalyst-Hydrogen bond strengths and optimizing performance in de/hydrogenation reactions.