Hierarchical Porous Catalyst Research Articles

Hierarchical macroporous/mesoporous NiCo2O4nanosheets as cathode catalysts for rechargeable Li–O2batteries

The key factor to improve the electrochemical performance of Li–O2 batteries is to find bi-functional cathode catalysts to promote the oxygen reduction and evolution reactions. Despite tremendous effects, developing cathode catalysts with high activity remains a great challenge. Herein, we report the synthesis of hierarchical macroporous/mesoporous NiCo2O4 nanosheets as an effective cathode catalyst for Li–O2 batteries. The hierarchical porous catalyst was synthesized by a hydrothermal method, followed by low temperature calcination. SEM and TEM observations clearly present that the as-prepared NiCo2O4 nanosheets showed a hierarchical porous structure with mesopores distributed through the surface of NiCo2O4 nanosheets and macropores formed between the crumpled nanosheets. When investigating as the cathode catalyst in Li–O2 batteries, the as-prepared NiCo2O4 nanosheets exhibited higher reversible capacity, lower charge/discharge overpotential, and better cycling stability than those of pristine carbon black. The enhanced electrochemical performance of NiCo2O4 nanosheets should be attributed not only to the high catalytic activity of NiCo2O4 towards oxygen reduction reaction and oxygen evolution reaction, but also to the novel hierarchical porous structure of NiCo2O4.

Influence of Al content on textural properties and catalytic activity of hierarchical porous aluminosilicate materials

A series of hierarchical porous aluminosilicate materials were prepared using hydrothermal treatment of the composite formed by polystyrene colloidal spheres and aluminosilicate gel. Influence of Al content on the textural properties, acidic properties and catalytic activity of the hierarchical porous aluminosilicate materials was studied. The results showed that textural and acidic properties of the hierarchical porous aluminosilicate materials were strongly related to Al content. As Al content is increased (n Si/n Al = 25), the hierarchical porous catalysts exhibited higher catalytic activity and major product selectivity for alkylation of phenol with tert-butanol than the catalysts with a lower Al content (n Si/n Al = 50).

An Overview of Recent Development in Composite Catalysts from Porous Materials for Various Reactions and Processes

Catalysts are important to the chemical industry and environmental remediation due to their effective conversion of one chemical into another. Among them, composite catalysts have attracted continuous attention during the past decades. Nowadays, composite catalysts are being used more and more to meet the practical catalytic performance requirements in the chemical industry of high activity, high selectivity and good stability. In this paper, we reviewed our recent work on development of composite catalysts, mainly focusing on the composite catalysts obtained from porous materials such as zeolites, mesoporous materials, carbon nanotubes (CNT), etc. Six types of porous composite catalysts are discussed, including amorphous oxide modified zeolite composite catalysts, zeolite composites prepared by co-crystallization or overgrowth, hierarchical porous catalysts, host-guest porous composites, inorganic and organic mesoporous composite catalysts, and polymer/CNT composite catalysts.