Efficient deposition of Pt nanoparticles on TiO2 nanosheets by regulating the defect concentration: Strengthening MSI for enhancing dehydrogenation of dodecahydro-N-ethylcarbazole

N-ethylcarbazole/dodecahydro-N-ethylcarbazole is a promising candidate for large-scale hydrogen storage, whereas the low dehydrogenation rate and selectivity make the dehydrogenation process full of challenges. In this study, TiO2 nanosheets with high oxygen vacancy concentration were successfully prepared by the simple solvothermal method followed by the annealing-quenching processes, and then the Pt nanoparticles were deposited through impregnation-reduction procedure. Among the Pt/TiO2 catalysts, the 2.5 wt% Pt/TiO2-600–3.0 catalyst showed the best dehydrogenation performance with 5.61 wt% H2 release amount and 91% selectivity of NECZ in 180 min at 453 K. It had the highest TOF of 1500.09 min−1 at 453 K up to now. Combined with various characterization methods, it was found that the high quenching temperature was conducive to increase oxygen vacancy concentration on TiO2 before the phase change, and the oxygen vacancies could be occupied by Pt nanoparticles. However, after the phase change of TiO2, the generated rutile TiO2 is difficult to form oxygen vacancies. Meanwhile, the structural–functional relationship of different Pt/TiO2 catalysts for 12H-NECZ dehydrogenation was explored. The surface electronic structure of the metal Pt was affected by the strong metal-support interaction (MSI), which was positively correlated with the electron-rich state of metal Pt. Both the increase of oxygen vacancy concentration and crystallinity of TiO2 could contribute to the enhancement of the MSI effect, and the optimized d-band centers of catalysts were beneficial for accelerating dehydrogenation efficiency. The reasonable defects on the catalyst surface could enhance the dehydrogenation kinetics and selectivity of NECZ, confirmed by experiments and DFT calculations.