In situ formation of cocatalytic sites boosts single-atom catalysts for nitrogen oxide reduction

Nitrogen oxide (NO_x) pollution presents a severe threat to the environment and human health. Catalytic reduction of NO_x with H₂ using single-atom catalysts poses considerable potential in the remediation of air pollution; however, the unfavorable process of H₂ dissociation limits its practical application. Herein, we report that the in situ formation of Pt_Ti cocatalytic sites (which are stabilized by Pt-Ti bonds) over Pt₁/TiO₂ significantly increases NO_x conversion by reducing the energy barrier of H₂ activation. We demonstrate that two H atoms of H₂ molecule are absorbed by adjacent Pt atoms in Pt-O and Pt-Ti, respectively, which can promote the cleave of H-H bonds. Besides, Pt_Ti sites facilitate the adsorption of NO molecules and further lower the activation barrier of the whole de-NO_x reaction. Extending the concept to Pt₁/Nb₂O₅ and Pd₁/TiO₂ systems also sees enhanced catalytic activities, demonstrating that engineering the cocatalytic sites can be a general strategy for the design of high-efficiency catalysts that can benefit environmental sustainability.