In Situ Construction of Interface with Photothermal and Mutual Catalytic Effect for Efficient Solar‐Driven Reversible Hydrogen Storage of MgH2

Abstract Hydrogen storage in MgH 2 is an ideal solution for realizing the safe storage of hydrogen. High operating temperature, however, is required for hydrogen storage of MgH 2 induced by high thermodynamic stability and kinetic barrier. Herein, flower‐like microspheres uniformly constructed by N‐doped TiO 2 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 MgH 2 using solar energy. N‐doped TiO 2 is in situ transformed into TiN x O y and Ti/TiH 2 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 TiH 2 and MgH 2 can not only thermodynamically and kinetically promote H 2 desorption from MgH 2 but also simultaneously weaken Ti─H bonds and hence in turn improve H 2 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 MgH 2 with a capacity of 6.1 wt.% under 27 sun.