Design and synthesis of functional electrospun ceramic fibres
Abstract:
Ceramic fibres are characterised by elongated thin-strand structures, which possess intriguing physical and chemical properties unachievable by bulk ceramics. These materials have sparked substantial interest for application in catalysis, sensing, energy conversion and storage, biomedical, environmental remediation, etc. This D. Phil project adopts a combination of electrospinning technique and sol-gel synthesis to produce high-performance ceramic fibres. The primary objectives are unravelling the mechanisms governing fibre formation and achieving better control over the micro- and macroscale fibre structures. The outcomes of this work are new functional fibre materials practically feasible for thermal insulation and photocatalysis applications.
A novel ‘3D sol-gel electrospinning technique’ is proposed for the in situ creation of centimetre-scale fibre macro-assemblies. This technique leads to fibre assemblies with highly tuneable macroscopic shape, volume, density, and porosity, effectively removing the limitation of conventional electrospinning that only yields 2D-like thin fibrous nonwovens with restricted implementation. Calcining the as-spun fibres produces ultralight ceramic fibrous assemblies (CFAs). Two materials are reported, TiO2/SiO2 CFA as a super-absorbent material for soaking up spillages and oil/water separation. Al2O3/ZrO2 CFA (AZFA) is a promising high-temperature thermal insulator showing ultralow thermal conductivity (less conductive than air) and ultrahigh thermal stability (1300-1500 °C). Surface modification endows AZFA hydrophobicity, allowing them to provide reliable thermal insulation in humid environments and underwater conditions.
3D electrospinning essentially tunes the macropores between fibres, while various pore-engineering strategies are used to manipulate the microstructures of individual fibres. Mesoporous and macroporous TiO2 fibres are synthesised by phase separation and sacrificial template methods. A dual-polymer templating method has been developed to create an ingenuous hierarchical porous fibre structure, the formation mechanisms and significantly enhanced optical responses are investigated experimentally and analytically. These porous TiO2 fibres are coupled with Au nanoparticle to form plasmonic photocatalysts with high-photocatalytic performance and excellent recyclability, proposed as superior materials for photocatalytic degradation of organic species in wastewater treatment.