Engineering interfacial hydrogen spillover in Ni-decorated graphitic carbon nitride for solvent-free stereoselective hydrogenation of biomass α-pinene into cis-pinane for sustainable aviation fuel applications

The catalytic valorization of renewable biomass into high-density sustainable aviation fuels (SAFs) represents a critical decarbonization pathway for the aviation sector. Among potential feedstocks, oxygen-free α-pinene is particularly attractive; however, its efficient solvent-free hydrogenation under mild conditions with non-precious metal catalysts remains a formidable challenge. Herein, we report a rationally designed Ni-decorated graphitic carbon nitride (Ni-GCN) catalyst fabricated via pyrolysis of an in-situ grown Ni-MOF/GCN composite, creating a unique architecture with well-defined interfaces, abundant active sites, and superior mass transport properties. In solvent-free α-pinene hydrogenation, Ni-GCN exhibits exceptional performance, achieving > 99 % conversion with 98.2 % stereoselectivity toward cis-pinane under mild conditions (65 ℃, 1.5 MPa H 2 ), substantially surpassing state-of-the-art non-noble metal catalysts and even rivaling commercial 5 wt% Pd/C. Systematic mechanistic investigations integrating kinetic analysis, H 2 -D 2 isotopic exchange, physical-mixture H-spillover activity assays, WO 3 colorimetric detection, and hydrogen temperature-programmed unequivocally reveal that superior activity stems from highly efficient interfacial hydrogen spillover. This spillover-mediated pathway sustains a 4.6-fold higher surface coverage of active hydrogen species on Ni-GCN relative to spillover-deficient Ni-C, directly translating to enhanced catalytic efficiency. Consequently, the turnover frequency of Ni-GCN reaches 6.28 h −1 , representing 1.4-fold and 3.2-fold enhancements over Ni-graphene (4.58 h −1 ) and Ni-C (1.97 h −1 ), respectively, with spillover contributing a 3-fold activity boost. Quantitative kinetic-spectroscopic correlation establishes spillover efficiency as the primary activity descriptor. DFT calculations validate this mechanism, revealing substantially lowered activation barriers for the spillover-assisted route. These findings establish interfacial spillover engineering as a robust strategy for earth-abundant catalyst development, offering molecular-level design principles for sustainable energy technologies.