Single Ti atoms coupled with Ti–O clusters enable low temperature hydrogen cycling by sodium alanate

Ti-based catalysts are known to improve the hydrogen storage performance of NaAlH 4 by facilitating the dissociation/recombination of H–H and Al–H bonds. The catalytic activity of metallic Ti species strongly depends on its particle size and dispersity. Ti clusters and even single atoms are therefore highly desirable, but their controllable fabrication has been highly challenging. Herein, we demonstrate a novel facile sonochemical synthesis of a Ti–O clusters featuring single Ti atom catalyst at room temperature. Through reducing TiCl 4 by MgBu 2 with ultrasound instead of heating as driving force, numerous single Ti atoms coupled with Ti–O clusters with Ti loading on graphene (Ti 1 /Ti–O@G) up to 22.6 wt% have been successfully obtained. The prepared Ti 1 /Ti–O@G contributes high reactivity and superior catalytic activity, therefore enabling full dehydrogenation of NaAlH 4 at 80 °C in thermogravimetric mode and re-hydrogenation at 30 °C and 10 MPa with 4.9 wt% H 2 . This fact indicates for the first time that single Ti atom catalyst with high loading is highly effective in catalyzing hydrogen cycling of NaAlH 4 at remarkably reduced temperatures. Graphical abstract