Core–shell construction of metal@carbon by mechanochemically recycling plastic wastes: towards an efficient oxygen evolution reaction

Abstract

Rational surface engineering of non-noble metal electrocatalysts supported on carbon materials (metal@C) provides potential opportunities to gain sustainable energy by electrocatalytic water splitting. Here, plastic waste-based electrode materials obtained by mechanochemical synthesis and in situ pyrolysis doping afford low overpotentials (η₁₀ = 263 mV, Tafel slope = 34 mV dec⁻¹), superior durability, and operation simplification. The ball milling treatment promoted solid dispersion of metal precursors in plastics, further constructing a core–shell structure with tunable thickness to regulate the activity. The metal species were encapsulated by a plastic-derived carbon shell and uniformly embedded in a highly porous carbon support. By changing the metal precursor, alternative OER electrocatalysts based on transition metal (Co, Ni, Mn and Fe) sites @C could accelerate the oxygen evolution kinetics, and the OER activity trend was Ni > Co ≈ Fe > Mn, superior to most carbon-based OER electrocatalysts and commercial IrO₂ used to date. The synergetic effect of the encapsulated metal and the high-curvature onion-like carbon shell plays a fundamental role in the superior OER catalytic performance. Furthermore, this method presents an approach for the efficient utilization and upward recycling of plastics as high-value electrode materials.