Effect of Hydroxyl Groups on Metal Anchoring and Formaldehyde Oxidation Performance of Pt/Al 2 O 3 .

Pt/Al 2 O 3 catalysts showing excellent activity and stability have been used in various reactions, including HCHO oxidation. Herein, we prepared Pt-Na/Al 2 O 3 catalysts with a Pt content of 0.05 wt % to reveal the key factors determining the anchoring of Pt as well as the catalytic activity and mechanism of HCHO oxidation. Pt-Na/nano-Al 2 O 3 (denoted as Pt-Na/nAl 2 O 3 ) catalysts with 0.05 wt % Pt content could completely oxidize HCHO to CO 2 at room temperature, which is the lowest Pt content used in HCHO catalytic oxidation to our knowledge. After Na addition, terminal hydroxyl groups (denoted as HO-μ ter ) on nano-Al 2 O 3 were transformed to doubly bridging hydroxyl groups between Na and Al (denoted as HO-μ bri(Na-Al) ), which atomically dispersed Pt species. Pt anchoring further promoted the regeneration of HO-μ bri(Na-Al) by activating O 2 and H 2 O, oxidizing HCHO to CO 2 directly by the fast reaction step ([HCOO - ] + [OH] a → CO 2 + H 2 O). Our study revealed that the HO-μ bri(Na-Al) synergistically generated by HO-μ ter and Na species provided anchoring sites for Pt species.