Photochemical route for synthesizing atomically dispersed palladium catalysts

TLDR

Atomically dispersed noble metal catalysts show high performance but require low loading (<0.5 %) to prevent sintering into nanoparticles. The authors propose a photochemical method to produce a stable atomically dispersed Pd₁/TiO₂ catalyst on EG‑stabilized ultrathin TiO₂ nanosheets with Pd loadings up to 1.5 %. The photochemical approach generates Pd₁ sites on TiO₂ nanosheets by irradiating EG‑stabilized TiO₂ in the presence of Pd precursors, yielding a uniform dispersion. The Pd₁/TiO₂ catalyst delivers nine‑fold higher C=C hydrogenation activity than commercial Pd, remains stable over 20 cycles, and achieves over 55‑fold enhancement in aldehyde hydrogenation via heterolytic H₂ activation.

Abstract

Atomically dispersed noble metal catalysts often exhibit high catalytic performances, but the metal loading density must be kept low (usually below 0.5%) to avoid the formation of metal nanoparticles through sintering. We report a photochemical strategy to fabricate a stable atomically dispersed palladium-titanium oxide catalyst (Pd1/TiO2) on ethylene glycolate (EG)-stabilized ultrathin TiO2 nanosheets containing Pd up to 1.5%. The Pd1/TiO2 catalyst exhibited high catalytic activity in hydrogenation of C=C bonds, exceeding that of surface Pd atoms on commercial Pd catalysts by a factor of 9. No decay in the activity was observed for 20 cycles. More important, the Pd1/TiO2-EG system could activate H2 in a heterolytic pathway, leading to a catalytic enhancement in hydrogenation of aldehydes by a factor of more than 55.