Synthesis of β‐MoO ₃ nanowhiskers from core/shell molybdenum/molybdenum oxide wire by pulsed wire discharge

Abstract β‐MoO _3, the molybdenum oxide phase with the highest catalytic activity, is a promising material in optical, chemical, and electronics applications as a replacement for α‐MoO ₃ . α‐MoO ₃ 1D nanostructures such as whiskers and fibers have been investigated and used in applications. However, difficulties in the synthesis of one‐dimensional β‐MoO ₃ have obstructed researchers in the study of its properties. In this research, β‐MoO ₃ nanowhiskers were synthesized from core/shell molybdenum/molybdenum oxide wires by pulsed wire discharge in mixed oxygen and argon gases. X‐ray diffraction analysis identified the main phase in the obtained samples as β‐MoO ₃ . Electron microscopy observations revealed whiskers with an average length and width of 216 nm and 23 nm, respectively. Transmission electron microscopy lattice imaging confirmed the successful synthesis of β‐MoO ₃ nanowhiskers. Various models were considered to explain the formation of β‐MoO ₃ nanowhiskers, including mechanical fragmentation of α‐MoO ₃ layers as well as vapor‐liquid‐solid and vapor‐solid mechanisms. The phase transformation from α to β‐MoO ₃ under a nucleation process was explained based on the Mo‐O phase diagram. To the best of our knowledge, this is the first report of β‐MoO ₃ nanowhisker synthesis.