As a catalyst, single atomic platinum may provide an ideal structure for platinum minimization by maximizing atom utilization. Single atomic platinum catalysts supported on titanium nitride nanoparticles were successfully prepared for use in electrocatalytic reactions. High-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and extended X-ray absorption fine structure (EXAFS) analysis revealed the atomic dispersion of platinum on the titanium nitride supports. The single atomic active sites resulted in unconventional selectivity for various electrocatalytic reactions. Unlike platinum nanoparticles, hydrogen peroxide was predominantly produced in the electrochemical oxygen reduction reaction that had the highest reported mass activity. Platinum nanoparticle catalysts break oxygen-oxygen bonds following a 4-electron pathway (O2 + 4H+ + 4e- → 2H2O), and the single atomic platinum catalysts preserve oxygen-oxygen bonds following a 2-electron pathway (O2 + 2H+ + 2e- → H2O2). The oxidation of small organic molecules, such as formic acid and methanol, also exhibited unique selectivity on the single atomic platinum catalyst. A lack of platinum ensemble sites changed the reaction pathway for formic acid oxidation toward direct dehydrogenation rather than indirect dehydration. The absence of the platinum ensemble also resulted in negligible activity for methanol oxidation. In addition to maximizing the activity per Pt unit mass, the single atomic catalysts exhibited unique selectivity due to the absence of the Pt ensemble.

Single atomic Pt catalyst for electrocatalytic reactions with unique selectivity

251st National Meeting (2016)

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