Fully exposed Pt_n cluster catalysts enable cascade oxidation of polyol to dicarboxylic acid

The polyol oxidation to dicarboxylic acid, a crucial value-accretive reaction, is still challenging due to the paradoxical relationship between efficient activation of C-H bond and rapid desorption of carboxylic acid. Herein, we break this contradiction by constructing fully exposed Pt_n cluster supported on hydroxyapatite (Pt_n/HAP) to promote two primary hydroxyl groups of polyol oxidation to dicarboxylic acid. Such fully exposed Pt_n cluster with an average Pt-Pt coordination number of ∼3.4 exhibits unique electronic properties between Pt₁ single atom and nanoparticle Pt_p. Specifically, gradient charge distribution in fully exposed Pt_n cluster shows a special synergistic effect in the C-H bond activation. Moreover, the d-band centre of fully exposed Pt_n cluster moderately far from the Fermi level weakens the adsorption of C = O bond in dicarboxylic acid product. As a result, fully exposed Pt_n/HAP with better catalytic activity (turnover frequency: 619.1 h⁻¹) shows nearly 10 times and 1.5 times of tartronic acid selectivity than Pt₁ single atom and nanoparticle Pt_p catalysts, respectively. The system is also applicable to other polyol oxidation to dicarboxylic acids with noteworthy catalytic results.