Balancing Ni encapsulation and oxygen vacancies in Ni@TiO2−x catalysts through strong metal–support interactions for efficient dibenzofuran hydrodeoxygenation

Eliminated Ni particle size effects to isolate intrinsic SMSI effects. • Decoupled the roles of Ni sites and interfacial Ni-O v -Ti 3+ sites. • Exposed Ni sites serve as the primary sites for H 2 activation and hydrogenation. • Interfacial Ni-O v -Ti 3+ sites promote oxygenated intermediate deoxygenation. • Balancing Ni encapsulation and oxygen vacancies maximizes HDO activity. Efficient hydrodeoxygenation is essential for upgrading biomass- and coal-derived oils into high-quality fuels. Although strong metal–support interactions (SMSI) have been employed to promote hydrodeoxygenation, how SMSI-induced metal encapsulation and oxygen vacancy generation individually and collectively govern hydrodeoxygenation remains unclear. To eliminate the confounding influence of Ni particle size, a series of Ni@TiO 2− x catalysts with uniform Ni particle sizes but tunable SMSI strengths were engineered through tailored pretreatment strategies. Using a remarkably simple kinetic strategy, the mixed roles of Ni sites and oxygen vacancies were successfully decoupled, proving that Ni encapsulation inhibits hydrogenation while oxygen vacancies drive deoxygenation. Consequently, the catalyst with intermediate SMSI strength strikes an optimal balance by maximizing the density of oxygen vacancies while mitigating excessive metal encapsulation, thereby delivering the highest hydrodeoxygenation activity. Density functional theory calculations further demonstrate that interfacial Ni-O v -Ti 3+ sites enhance the adsorption of oxygenated intermediates and markedly lower the C–O bond activation barrier. The cooperative interplay between exposed metallic Ni sites and interfacial Ni-O v -Ti 3+ sites orchestrates H 2 activation and C–O bond cleavage, thereby enabling efficient hydrodeoxygenation and providing a design principle for SMSI-regulated interfacial catalytic systems. Download: Download high-res image (159KB) Download: Download full-size image