Novel electrocatalysts for hydrogen evolution based on carbon fibers modified by cobalt phosphides

Effect of heat treatment on the morphology of carbon fibers doped with Co2p nanoparticles

“…The mechanism of CNTs growth has been previously discussed by many other authors; however, the upraise of CNTs in situ by affecting temperature is very rare (Kumar and Ando 2010;Pérez-Cabero et al 2004;Zhao et al 2006;Yuan et al 2003;Mo et al 2001;Vinciguerra et al 2003). As mentioned in the authors' previous work, Co and Co 2 P nanoparticles can initiate the growth of CNTs as described in the "tip growth model" (Streckova et al 2020). The suggested mechanism of growth and deterioration of carbon nanotubes affected by the prolongation of exposure times at 1200 °C is depicted in Scheme 1.…”

“…Distinctive properties of carbon materials, such as wide operating potential, large variability of modifications by shaping or easy incorporation into other materials, low cost and inertness against most electrolytes, make them suitable catalysts for HER. However, amorphous carbon is an electroactive inert and possesses poor catalytic activity (Streckova et al 2020). Therefore, it is necessary to supplement other catalysts into the carbonaceous materials that increase their electrocatalytic activity.…”

“…Alternatively, one may design more suitable carbon structures such as carbon fibers (CFs), carbon nanotubes (CNTs) single-walled CNTs (SWCNTs), graphene, or glassy paper. It is known that the incorporation of transition metal nanoparticles (TMN), such as Co, Cu, Ni, Fe, significantly increases the electrocatalytic activity, the efficiency of catalysts (Zhou et al 2016;Shi and Zhang 2016;Kong et al 2013), and also initiates the growth of carbon nanotubes (CNTs) (Streckova et al 2020). Carbon with tubular nanostructures such as CNTs and SWNTs has attracted considerable attention not only because of its fascinating, unique physicochemical properties, but also due to its promising applications in transistors (Bachtold et al 2001), field-emission tips (Iijima 1991), sensors (Zhu et al 2002), supercapacitors (An et al 2001, and bio-medical fields (Zanello et al 2006).…”

“…); ii. modification of CF (Streckova et al 2020)-surface or interior modification by additional nanoparticles or additives (CNT growth on the surface, type of TMN, etc. ); iii.…”

“…Cobalt phosphate nanoparticles have been incorporated into the carbon matrix in situ in the heat treatment process and act as the catalysts for CNT growth during sintering. The growth of CNT was performed according to the "Tip growth model" (Streckova et al 2020).…”