Upcycling Spent LiCoO2 Cathodes via Surface Spinel Reconstruction for Efficient Furfural Hydrogenation.

Spent lithium-ion batteries represent a growing environmental challenge, yet their transition-metal-rich cathodes remain largely underutilized as functional materials. We report a direct upcycling strategy in which LiCoO2 cathodes recovered from end-of-life smartphones are transformed into efficient heterogeneous catalysts via a single-step oxidative calcination (600 °C, 6 h, air). The resulting material retains a predominantly layered Li1-xCoO2 structure with a minor spinel-like phase formed during treatment. This reconstructed fraction significantly enhances cobalt reducibility, introducing a low-temperature reduction feature absent in the untreated precursor. Under 20 bar H2 at 180 °C, the catalyst selectively converts furfural to furfuryl alcohol at short reaction times, while prolonged reaction promotes further hydrogenation to tetrahydrofurfuryl alcohol, enabling tunable selectivity. Compared with the untreated precursor and commercial references, the calcined material shows markedly improved catalytic activity. Computational simulations reveal that the spinel-like phase provides the most favorable adsorption and activation of furfural, identifying it as the dominant catalytic motif. Catalyst deactivation is reversible, and activity is largely restored by a simple recalcination step. These results establish spent LiCoO2 cathodes as readily accessible cobalt-based catalysts for upgrading biomass-derived platform molecules, providing a circular route that couples battery-waste valorization with sustainable chemical manufacturing.