Kuan Tian

Hierarchical porous microspheres of activated carbon with a high surface area from spores for electrochemical double-layer capacitors

Owing to the advantages of high surface area, good conductivity, sustainability, and chemical stability, biomass-based activated carbon materials have been one of the research hotspots in the field of supercapacitors. Yet common techniques to synthesize nanostructured electrodes of activated carbon only offer limited control on their morphology and structure. In this work, three-dimensional porous hollow microspheres of activated carbon are fabricated by utilizing various spores (Lycopodium clavatum, Ganodorma lucidum and Lycopodium annotinum spores) as carbon precursors and self-templates through a facile, green and low-cost route. The abundant and easily available carbon sources of spores allow for mass production of activated carbon microspheres (ACMs), which almost ideally inherit the distinctive nano-architectures of spores, presenting a superhigh specific surface area (up to 3053 m2 g−1) and hierarchical porous structure. Such ACM electrodes show remarkable electrical double-layer storage performances, such as high specific capacitance (308 F g−1 in organic electrolytes), ultrafast rate capability (retaining 263 F g−1 at a very high current density of 20 A g−1) and good cycling stability (93.8% retention after 10 000 charge–discharge cycles), thus leading to a high energy density (57 W h kg−1) and superior power density (17 kW kg−1).

Bio-templated fabrication of hierarchically porous WO3 microspheres from lotus pollens for NO gas sensing at low temperatures

Lotus pollens were used as templates to prepare WO3 microspheres; the intriguing structural features of the pollens, e.g. hollow sphere with highly porous double shells, were perfectly inherited by the WO3 microspheres. The hierarchically porous structure of the WO3 microspheres was ideal for gas sensing. The WO3 microsphere-based sensor exhibited a high sensitivity (S = 46.2) to 100 ppm NO gas with a pretty fast response and recovery speed (62 s/223 s) at 200 °C. Compared with NO sensors reported in the literature so far, the WO3 microsphere-based sensor has among the highest sensitivity and fastest response/recovery.

Hierarchical and Hollow Fe2O3 Nanoboxes Derived from Metal–Organic Frameworks with Excellent Sensitivity to H2S

Hierarchical and hollow porous Fe2O3 nanoboxes (with an average edge length of ∼500 nm) were derived from metal-organic frameworks (MOFs) and the gas sensing characteristics were investigated. Sensors based on Fe2O3 nanoboxes exhibited a response (resistance ratio) of 1.23 to 0.25 ppm (ppm) hydrogen sulfide (H2S) at 200 °C, the response/recovery speed is fast and the selectivity to H2S is excellent. Remarkably, the sensor showed fully reversible response to 5 ppm of H2S at 50 °C, demonstrating its promise for operating at near room temperature, which is favorable for medical diagnosis and indoor/outdoor environment monitoring. The excellent performance of the Fe2O3 nanoboxes can be ascribed to the unique morphology with high specific surface area (SSA) and porous nanostructure.