In Situ Construction of Interface with Photothermal and Mutual Catalytic Effect for Efficient Solar-Driven Reversible...

Hydrogen storage in MgH₂ is an ideal solution for realizing the safe storage of hydrogen. High operating temperature, however, is required for hydrogen storage of MgH₂ induced by high thermodynamic stability and kinetic barrier. Herein, flower-like microspheres uniformly constructed by N-doped TiO₂ nanosheets coated with TiN nanoparticles are fabricated to integrate the light absorber and thermo-chemical catalysts at a nanometer scale for driving hydrogen storage of MgH₂ using solar energy. N-doped TiO₂ is in situ transformed into TiN_xO_y and Ti/TiH₂ uniformly distributed inside of TiN matrix during cycling, in which TiN and Ti/TiH_x pairs serve as light absorbers that exhibit strong localized surface plasmon resonance effect with full-spectrum light absorbance capability. On the other hand, it is theoretically and experimentally demonstrated that the intimate interface between TiH₂ and MgH₂ can not only thermodynamically and kinetically promote H₂ desorption from MgH₂ but also simultaneously weaken Ti─H bonds and hence in turn improve H₂ desorption from the combination of weakened Ti─H and Ti─H bonds. The uniform integration of photothermal and catalytic effect leads to the direct action of localized heat generated from TiN on initiating the catalytic effect in realizing hydrogen storage of MgH₂ with a capacity of 6.1 wt.% under 27 sun.