Integrated co-axial electrospinning for a single-step production of 1D aligned bimetallic carbon fibers@AuNPs–PtNPs/NiNPs–PtNPs towards H2 detection

Abstract

One dimensional (1D) nanostructures such as nanorods, nanowires, nanotubes and nanofibers have aroused great attention owing to their exceptional properties like high surface-to-volume ratio and excellent electron and thermal transport and also act as interconnects during the fabrication of nanoscale devices. In this work, one dimensional aligned carbon nanofibers (CFs)@AuNPs–PtNPs/NiNPs–PtNPs have been developed via a single step co-axial electrospinning integrated with in situ photo-reduction. The carbon nanofibers with in situ functionalized bimetallic nanoparticles possessed a well-defined core–shell structure with carbon nanofibers (CFs) as the core and AuNPs–PtNPs/NiNPs–PtNPs as the surface anchored heterojunctions. Homogeneously distributed AuNPs–PtNPs/NiNPs–PtNPs, which are identified as chemical sensitizers, trigger the dissociation of H₂ through the spillover effect, by successive diffusion of the H⁺ on the carbon nanofiber surface, thereby altering the entire surface of the CFs into reaction sites for H₂. Aligned core–shell CFs@NiNPs-PtNPs possessed high sensitivity of 124% (v/v) at room temperature compared to aligned core–shell CFs@PtNPsNPs (52%) and aligned core–shell CFs@AuNPs–PtNPs (65%), which may be due to the high catalytic adsorption and desorption properties of Ni and Pt towards hydrogen gas. Moreover, co-axially aligned CF@NiNP–PtNP based sensor also demonstrates outstanding selectivity towards hydrogen compared to other gases like ammonia, ethanol, hydrogen sulphide, and acetone with excellent long-term stability. In addition, hydrogen adsorption kinetics of the co-axially aligned CF@NiNP–PtNP based sensor was verified theoretically with an adsorption rate constant of 0.42 which is comparable to the experimental value (0.38) of adsorption rate constant. The potential suitability of the co-axially aligned CF@NiNP–PtNP based sensor towards H₂ at room temperature for real time applications has also been demonstrated.