Thermocatalytic Upcycling of Plastic into Ni-Encapsulated Carbon Nanotube Electrocatalysts for Green Hydrogen Production

The escalating accumulation of plastic waste poses a critical environmental challenge. Here, we report a controllable solvent- and H2-free disassembly (CSHFD) strategy using Ni-decorated nanoparticles (NPs) on ordered microporous carbon (Ni-OMC) for plastic upcycling. The optimized Ni20-OMC (20 wt % Ni NPs) achieved an H2 yield of 55.26 mmol g–1 plastic with an H2 proportion of 86.86 vol %, attributed to the abundant metallic Ni active sites on the carbon skeleton that facilitated C–C and C–H bond cleavage. Notably, the in situ formation of plastic-derived carbon nanotubes (CNTs) encapsulating metallic Ni NPs on microporous carbon (Ni-CNTs-OMC) as functionalized nanocomposites bridged thermocatalysis and electrocatalysis. Remarkably, the Ni20-CNTs-OMC (CNTs anchored on Ni20-OMC) exhibited superior hydrogen evolution reaction (HER) performance in alkaline electrolyte, requiring an overpotential of only 215 mV at 10 mA cm–2 and retaining robust stability over 15,000 cycles. In situ attenuated total reflection surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) revealed strengthened hydrogen-bond networks and optimized *H adsorption, accelerating HER kinetics. Density functional theory (DFT) calculations further indicated that the Ni-encapsulated CNT structure modulated CNT electron distribution and lowered the Gibbs free energies of HER intermediates. Simply put, this work offers a sustainable and integrated approach to transform plastic waste into high-performance electrocatalysts and green H2, establishing a paradigm for bridging thermocatalysis and electrocatalysis toward a circular carbon economy.