Pt/C electrocatalysts based on the nanoparticles with the gradient structure

Effective Platinum-Copper Catalysts for Methanol Oxidation and Oxygen Reduction in Proton-Exchange Membrane Fuel Cell

“…Secondly, it is necessary to determine, whether such de-alloyed PtCu x−y /C catalysts retain high stability and activity in ORR and MOR, which are characteristic of the previously studied alloyed PtCu x /C catalysts [27][28][29][30][31]. Note that uneven distribution of the doping component atoms in the "body" of the initial PtM nanoparticles obtained during the synthesis, as well as the changes in conditions of their de-alloying can apparently affect both the composition and activity/stability of the de-alloyed catalysts [21,22,[32][33][34][35]. Thus, the search for the best PtCu compositions and structures of bimetallic nanoparticles, selection of the optimal conditions for the transformation of alloyed PtCu x /C catalysts into a de-alloyed state, as well as the study of the de-alloyed PtCu x−y /C catalysts behavior, proves to be timely and relevant.…”

“…Vulcan XC-72 carbon-supported platinum-copper catalysts were prepared by a four-stage synthesis in the liquid phase, sodium borohydride being used as a reducing agent as described in [22]. Initially, copper nanoparticles were deposited on a carbon support from a CuSO 4 solution.…”

“…To reduce the content of the precious metal in the bimetallic catalyst, while increasing its activity in current-forming reactions, attempts have been made to optimize the composition and structure of platinum-containing nanoparticles [10,13,[18][19][20][21][22][23][24]. Note that the features of the hierarchical structural organization of PtCu/C catalysts are determined not only by the shape and size of the metal nanoparticles, but also by their spatial distribution on the surface of the support, and have a crucial effect on the activity of catalysts in ORR and MOR [20][21][22][23]. The evaluation of some PtCu/C catalysts activity and stability in ORR and MOR obtained in electrochemical cells clearly indicates their high functional characteristics [20][21][22]24].…”

“…Note that the features of the hierarchical structural organization of PtCu/C catalysts are determined not only by the shape and size of the metal nanoparticles, but also by their spatial distribution on the surface of the support, and have a crucial effect on the activity of catalysts in ORR and MOR [20][21][22][23]. The evaluation of some PtCu/C catalysts activity and stability in ORR and MOR obtained in electrochemical cells clearly indicates their high functional characteristics [20][21][22]24]. Unfortunately, the composition of bimetallic nanoparticles changes in the process of their functioning: there is a selective dissolution of atoms of the alloying component.…”

“…The direct synthesis of such catalysts is rather problematic, but one could try to obtain them from the copper rich PtCu x /C (x > 1) materials by treating them in acids. It is important to make it sure that, firstly, the predominant dissolution of Cu atoms allows the formation of a secondary Pt shell that protects the internal copper atoms from dissolution [22,27,28]. Secondly, it is necessary to determine, whether such de-alloyed PtCu x−y /C catalysts retain high stability and activity in ORR and MOR, which are characteristic of the previously studied alloyed PtCu x /C catalysts [27][28][29][30][31].…”