Hydrogen Spillover-Induced Brønsted Acidity Enables Controllable Hydrocracking of Polyolefin Waste to Liquid Fuels

Efficient upcycling of polyolefin waste into liquid fuels remains challenging due to over-cracking and the lack of sufficient acidity in non-zeolitic catalysts. Here, we report a Ni/niobium oxide nanorod (Ni/NbO_x) catalyst that achieves 95% selectivity to C_5–20​ alkanes at full polyethylene (PE) conversion under mild conditions (240 °C), with minimal gaseous products (4%). The catalyst reaches a high liquid fuel formation rate of 1274 g_liquid​ g_Ni⁻¹​ h⁻¹, rivaling noble metal systems. Its performance is governed by the morphology and crystallinity of NbO_x nanorods, which provide sufficient acidity without micropore confinement, mitigating diffusion limitations and over-cracking. Detailed operando infrared spectroscopy and computational studies reveal, for the first time, that Brønsted acid sites, generated in situ via hydrogen spillover on the (110) facet, are the key catalytic sites in niobium oxide-based catalysts. The density of these acid sites exhibits a linear correlation with hydrocracking activity. The catalyst also demonstrates high efficiency across diverse polyolefin feedstocks and excellent reusability, offering a scalable and cost-effective solution for plastic upcycling.