Strong metal-support interactions of TiO2 interface-loaded Pt constructed under different atmospheres for adjusting the hydrogen storage reaction performance of N-ethylcarbazole.

ABSTRACT

In this study, two series of samples (rT-Pt/TiO2 prepared with a hydrogen pretreatment and Tr-Pt/TiO2 prepared with an oxygen pretreatment) were prepared by treating commercial TiO2 supports in different atmospheres to establish different TiO2 interfacial structures, followed by the addition of platinum nanoparticles (NPs) for the catalyzed hydrogenation/dehydrogenation cycle of N-ethylcarbazole (NEC). The kinetic analysis and reaction mechanism were investigated by combining XRD, Raman, CO-DRIFT, HRTEM, XPS, H2-TPD and DFT calculations. It was found that the performance of the samples for the NEC system's cyclic hydrogen storage could be modulated by treating the TiO2 interfacial structure with different atmospheres varying the extent of strong metal-support interaction (SMSI). In addition, a turnover frequency (TOF) of 191.52 min-1 for dehydrogenation was achieved at 170 °C, which is better than the previously reported catalysts. Experimental studies (characterization and kinetic studies) and DFT calculations confirmed that the SMSI of the Tr-Pt/TiO2 series samples promoted the escape of H2 and enhanced the catalytic activity for 4H-NEC in the 12H-NEC dehydrogenation reaction. In the NEC hydrogenation reaction, the rT-Pt/TiO2 series samples were pretreated with H2 before loading platinum metal, which led to the early activation of Ti4+ in their carriers, and thus suppressed the SMSI effect of the reduction process after loading platinum. This process caused the interface formed by rT-Pt/TiO2 to have a higher energy barrier to 6H-NEC, which is an intermediate product of the NEC hydrogenation process, and this interrupted the hydrogenation process of 6H-NEC.