Fully exposed Ptn 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 Ptn cluster supported on hydroxyapatite (Ptn/HAP) to promote two primary hydroxyl groups of polyol oxidation to dicarboxylic acid. Such fully exposed Ptn cluster with an average Pt-Pt coordination number of ∼3.4 exhibits unique electronic properties between Pt1 single atom and nanoparticle Ptp. Specifically, gradient charge distribution in fully exposed Ptn cluster shows a special synergistic effect in the C-H bond activation. Moreover, the d-band centre of fully exposed Ptn cluster moderately far from the Fermi level weakens the adsorption of C = O bond in dicarboxylic acid product. As a result, fully exposed Ptn/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 Ptp catalysts, respectively. The system is also applicable to other polyol oxidation to dicarboxylic acids with noteworthy catalytic results.