Nanoscale materials have received considerable attention employing their unique properties and a wide range of applications relative to their bulk counterparts [1, 2]. Nanomaterials can be classified into zero-, one-, and two- dimensional structures depending on the shape and size. Among the one dimensional (1D) nanostructures, nanowires play a significant role in device fabrication [3–5]. The properties of the nanomaterials are strongly influenced by their size, shape, and morphology. The diameter (< 10 nm) of the nanowires (NWs) introduces quantum-confined size effects, modifying the structural, electronic, optical, thermal, and magnetic properties. This enables its use in micro and nanoelectromechanical systems, sensors, and photodetectors [1, 6–9]. The wide bandgap exhibited by NWs makes it suitable for applications in light-emitting diodes, photovoltaics, and nanoscale lasers [1, 10]. NWs having high-temperature stability and high-frequency performance are essential in the development of electronic and optoelectronic systems.
Of different materials - metals, polymers, semiconductors, insulators, and ceramics - NWs of ceramic materials have gained attention recently due to their characteristic properties and widespread applications in the area of magnetic nanocomposites, quantum electronic materials, gas separations, and structural reinforcements. Ceramic materials are high strength materials and are chemically and thermally stable. Among ceramic materials, boron carbide (BC) finds widespread applications - lightweight armors, blast nozzles, ceramic bearing, brake linings, cutting tools, rocket propellant in the aerospace industry, and neutron absorber and shielding material in the nuclear industry [11–14] - due to its unique properties - greater hardness, high thermal and chemical stability, high neutron absorption cross-section, corrosion resistivity, and high melting point [15–17]. The lower fracture toughness of bulk BC is overcome by the 1D BC nanostructures having high elastic modulus [18]. The enhanced physical and electrical properties of BC NWs are responsible for the high temperature and power applications. The field emission properties of BC NWs make them a potential candidate as cathode materials [19, 20].
The performance of 1D BC nanostructures is greatly influenced by the synthesis condition [21]. Several methods, such as template-based synthesis, microwave radiation, chemical vapor deposition, and synthesis using polymer precursors, are available to produce different morphological structures of BC [22–28]. Zhang et al. [29] synthesized BC nanowires using a plasma-enhanced chemical vapor deposition method, and high pure BC NWs are prepared by Ma et al. using the thermal evaporation method [30]. Most of these methods need pre-process conditions such as catalyst preparation, substrate, and template preparation. Despite these methods, a more convenient low-temperature method for producing BC NWs has high demand and interest.
The condensation method is one of the low-temperature synthesis methods used for BC’s production using inexpensive organic precursors such as glycerin, citric acid, and polyvinyl alcohol (PVA) [31–33]. The usage of polymeric precursors enables control over the final product’s properties and structures by varying the precursor composition at low-temperatures [11, 34, 35]. Based on the above advantages of polymeric precursors, the bulk BC structure can be tailored to NWs by choosing the correct precursor ratio and suitable synthesis temperature. In this research work, a low-temperature condensation method is selected to synthesize BC NWs using readily available natural carbon source, castor oil.