A novel and facile approach to obtain NiO nanowire-in-nanotube structured nanofibers with enhanced photocatalysis.

NiO nanowire-in-nanotube structured nanofibers were easily and directly fabricated via one-pot uniaxial electrospinning followed by calcination process for the first time. Firstly, Ni(CH 3 COO) 2 /PVP composite nanofibers were prepared by a conventional electrospinning method, and then NiO nanowire-in-nanotube structured nanofibers were successfully synthesized by two-stage calcination procedure of Ni(CH 3 COO) 2 /PVP composite nanofibers which was determined to be the key process for preparing NiO nanowire-in-nanotube structured nanofibers. The NiO nanowire-in-nanotube structured nanofibers have pure cubic phase structure with space group of Fm3̄m , and the outer diameter and wall thickness of nanotubes and nanowire diameter are 130 ± 0.99 nm, 30 nm and 40 nm, respectively. Preliminarily, it is satisfactorily found that NiO nanowire-in-nanotube structured nanofibers used as photocatalyst for water splitting exhibit higher H 2 evolution rate of 622 μmol h -1 than counterpart NiO hollow nanofibers of 472 μmol h -1 owing to its novel nanostructure. The possible formation mechanism of NiO nanowire-in-nanotube structured nanofibers is proposed. To evaluate the universality of this novel preparative technique, taking Co 3 O 4 as an example, it is found that Co 3 O 4 nanowire-in-nanotube structured nanofibers are also successfully fabricated via this novel method. The special nanowire-in-nanotube structure of the one-dimensional nanomaterials makes them have promising applications in catalysis, lithium-ion battery, drug delivery, etc . This manufacturing strategy has some advantages over other methods to form nanowire-in-nanotube structured nanofibers, such as easy, highly efficient and cost effective. The design idea and synthetic technique provide a novel perspective to create other nanowire-in-nanotube structured nanomaterials.