Generation of Pd@Ni‐CNTs from Polyethylene Wastes and Their Application in the Electrochemical Hydrogen Evolution Reaction

Most polyethylene‐based plastics are used only few times, but the wastes resulted from them need hundreds of years to degrade completely in natural environment. Consequently, innovative treatment methods are highly desired to deal with these wastes thoroughly and convert them into more useful materials. Here in, carbon nanotubes with Ni particles encapsulation (marked as Ni‐CNTs) were synthesized in supercritical carbon dioxide system at 650 °C for 3 h firstly. The prepared Ni‐CNTs were tens of microns in length and 100 nm in diameter, and 20 wt% of Ni nanoparticles with a diameter of 100 nm were contained at the top of the carbon nanotubes. About 60.7 wt% carbon in the polyethylene wastes was converted to carbon nanotubes. Then Ni‐CNTs were modified by Pd (marked as Pd@Ni‐CNTs), and a plenty of Pd nanoparticles with a size of 10 nm were prepared on the surfaces of CNTs. The water splitting performance of the products was also obviously improved, and the overpotential can reach to 62 mV in N 2 ‐saturated 0.5 M H 2 SO 4 electrolyte with 7.5 wt.% of Pd. As the content of Pd increased, the performance of the products was also reinforced. At last, the performance of the catalyst can be comparable with commercial Pt/C catalyst.