Fig nbsp xA SEM images of Ni deposition

NaBH4 is usually used as reducing agent in alkaline electroless bath for electroless nickel–boron coatings where boron contents vary from 4 to 7 wt.% [34]. In electroless Ni–B process, Ni2 + ions are reduced by BH4− and boron is co-deposited with nickel continuously on activated surface. The coating obtained from Ni–B bath is composed of Ni and B element, which leads to an outstanding resistance to wear and abrasion. NaBH4 is the most powerful reducing agent available for the electroless nickel plating [34]. In this Preladenant study, firstly, Ni2 + ions were reduced by BH4− preferentially and Ni0 particles as catalyst were formed on the surface. Then Ni2 + ions were reduced by H2PO2− with the help of Ni0 catalyst and phosphorus was co-deposited with nickel continuously on the surface of PEEK/MWCNT. The coating obtained from Ni–P bath in this study was analyzed by EDS (Fig. 8(b)) and it was composed of Ni (88 wt.%) and P (12 wt.%). It has been reported that the Ni–P alloy coating with high phosphorus content (10–14 wt.%) has better corrosion resistant and ductility than that of Ni–B coating [34]. This ensures that Ni–P coated PEEK/MWCNT can be used in multitudinous corrosive environments. And considering the excellent chemical stability and hydrophobic surface of PEEK, we speculate that this method is also suitable for directly inducing other metals' (such as copper) electroless deposition on many kinds of substrates (such as ABS, polycarbonate, and materials with rough surface).