Strengthening Sn-MOF with SiO2/GeO2 Nanoparticles for Synergistically Enhanced High Capacity and Cycle Stability.

Metal-organic frameworks (MOFs) based on tin (Sn) have shown great potential as materials for lithium storage, thanks to their ability to alleviate volume expansion due to the homogeneous distribution of Sn in a porous matrix framework. However, the weak mechanical strength of the porous Sn-MOF structure has been a major challenge, leading to pulverization during the discharging/charging process. To overcome this issue, we have developed a feasible strategy to strengthen the Sn-MOF mechanical properties by incorporating SiO2/GeO2 nanoparticles during the synthesis process. The resulting composites of Sn-Si and Sn-Ge exhibited high energy density and long-term cycle stability, thanks to their synergistic effect in alloying and conversion reactions. Our density functional theory (DFT) calculations have revealed that the rigid SiO2/GeO2 nanoparticles enhance the Sn-MOF mechanical properties, including Young's and shear moduli, which contribute to the long-term cycle stability of these composites.

Pd/δ-MnO2 nanoflower arrays cordierite monolithic catalyst toward toluene and o-xylene combustion.

Exploring high-efficiency and stable monolithic structured catalysts is vital for catalytic combustion of volatile organic compounds. Herein, we prepared a series of Pd/δ-MnO2 nanoflower arrays monolithic integrated catalysts (0.01-0.07 wt% theoretical Pd loading) via the hydrothermal growth of δ-MnO2 nanoflowers onto the honeycomb cordierite, which subsequently served as the carrier for loading the Pd nanoparticles (NPs) through the electroless plating route. Moreover, we characterized the resulting monolithic integrated catalysts in detail and evaluated their catalytic activities for toluene combustion, in comparison to the controlled samples including only Pd NPs loading and the δ-MnO2 nanoflower arrays. Amongst all the monolithic samples, the Pd/δ-MnO2 nanoflower arrays monolithic catalyst with 0.05 wt% theoretical Pd loading delivered the best catalytic performance, reaching 90% toluene conversion at 221°C at a gas hourly space velocity (GHSV) of 10,000 h-1. Moreover, this sample displayed superior catalytic activity for o-xylene combustion under a GHSV of 10,000 h-1. The monolithic sample with optimal catalytic activity also displayed excellent catalytic stability after 30 h constant reaction at 210 and 221°C.