Search

To effectively solve the electrochemical degradation problem of commercial Pt/C catalyst in fuel cell, nitrogen doped titania oxynitride (N-TiO 2) decorated Pt low-coordinated sites on a commercial Pt/C catalyst is achieved by coupling single-cycle selective atomic layer deposition of TiO 2 and following nitriding process that exhibits outstanding durability enhancement without changing the size distribution and wasting the electrochemical active area of Pt. [Display omitted] • TiO 2 was selectively decorated on Pt nanoparticles by atomic layer deposition. • The nitridation of TiO 2 stabilized the defect sites on Pt nanoparticles. • N-doped TiO 2 kept the exposure of Pt nanoparticles active sites. • N-doped TiO 2 decorated Pt/C showed durability promotion in fuel cell. The electrochemical dissolution of platinum (Pt) based nanoparticles and the consequent Pt active sites losses and particle aggregation have become a critical stability issue for the commercial proton exchange membrane fuel cell. Herein, nitrogen doped titania (N-TiO 2) stabilized Pt low-coordinated sites on a commercial Pt/C catalyst is achieved by simply coupling selective atomic layer deposition of TiO 2 and following nitrogen doping process. Selectively deposited N-TiO 2 on Pt nanoparticles keeps the exposure of Pt sites on (111) facets and increases the reduction states of Pt, which results in 1.7 times improvement of mass activity than commercial Pt/C. Besides, N-TiO 2 stabilized commercial Pt/C catalyst exhibits outstanding durability enhancement, showing only a 14.0% loss of mass activity after 30,000 potential cycles of rotating disk electrode tests and 91.7% retention after durability tests in humid fuel cell condition. The shielding role of N-TiO 2 could effectively inhibit the degradation of low-coordinated sites on Pt nanoparticles and maintain Pt size distribution, which is a promising strategy to prolong the lifetime of commercial Pt/C catalysts. [ABSTRACT FROM AUTHOR]

The preparation of ultra-small structurally ordered Pt-based intermetallic nanocrystals (< 3 nm) is still challenging due to the sintering during high temperature ordering. We report a strategy to construct size and distribution controllable Pt-based intermetallic nanocrystals based on ultra-thin metal oxide coating on Pt nanoparticles via atomic layer deposition. The area-selective and thickness controllable metal oxide coatings can not only provide metal atoms for alloying, but also prevent the sintering of Pt nanoparticles during subsequently fast ordering reduction. The prepared uniform PtZn intermetallic nanocrystals with the size of 2.50 ± 0.65 nm achieve outstanding single-cell performance with the mass activity of 0.48 A mg Pt −1 at 0.9 V and 10.42 % loss of mass activity after 30,000 voltage cycles, which is superior to commercial Pt/C. The enhanced activity and durability is attributed to the decreased binding energy of Pt-oxygen intermediates for weakly polarized surface Pt atoms and suppressed electrochemical Ostwald ripening. [Display omitted] • Uniform sub-3 nm PtZn intermetallic is synthesized by selectively coating ultra-thin ZnO on Pt nanoparticles via atomic layer deposition. • Ultra-thin ZnO coating can provide Zn atoms for alloying and prevent the sintering of nanoparticles during ordering reduction. • The enhanced activity is attributed to the decreased binding energy of Pt-oxygen intermediates for weakly polarized surface Pt atoms. • Sub-3 nm PtZn intermetallic nanocrystals with uniform size distribution suppress electrochemical Ostwald ripening in acid conditions. [ABSTRACT FROM AUTHOR]