PtM (M = Fe, Co, Ni) Bimetallic Nanoclusters as Active, Methanol-Tolerant, and Stable Catalysts toward the Oxygen Reduction Reaction

Abstract

Tailoring PtM (M = Fe, Co, Ni) bimetallic electrocatalysts into nanoclusters (NCs) without any protective agents with diameters of about 2–5 nm is considered as an effective strategy to improve electrochemical performance, reduce the mass loading of precious Pt, and enhance methanol tolerance in the oxygen reduction reaction (ORR). However, how to synthesize bimetallic NCs with relatively controllable size and how to anchor and disperse PtM (M = Fe, Co, Ni) bimetallic NCs onto a suitable matrix are key issues to guarantee durable catalytic performance and stability of bimetallic NCs because NCs possess high surface energy, and it is easy for them to aggregate. Hence, in this paper, we demonstrated a low-temperature impregnation–reduction method to fabricate PtM (M = Fe, Co, Ni) bimetallic NCs without any protective agents immobilized on XC-72 carbon with a 10 wt % PtM loading, which exhibited more satisfactory ORR performance. In particular, PtNi/C presented the best ORR catalytic activity among the three catalysts and commercial Pt/C (20 wt % Pt loading) due to the synergistic effects of the unique electronic structure, smaller particle size, and stable adhesion with substrate. Electrochemical characterization indicated that a maximal catalytic activity was achieved at a Pt:Ni atomic ratio 0.8:0.2, and the mass activity (MA) was about 2.74 times greater than that of Pt/C. Furthermore, the Pt0.8Ni0.2/C catalyst possessed notable methanol tolerance and stability, which is vital for practical applications. As a result, this facile and effective synthesis strategy opens up new horizons to promote direct methanol fuel cells (DMFCs) into practical applications.

Enhancement of oxygen reduction activity and stability via introducing acid-resistant refractory Mo and regulating the near-surface Pt content

“…As displayed in Fig. 4 (c), the Pt 4 f orbit of PtNiMo ternary alloys moves to a higher binding energy compared with Pt/C, which will lower the d -band center of Pt and thus improve the catalytic activity for ORR [22] . Furthermore, as illustrated in Fig.…”

“…In order to address these problems, researchers have developed low Pt containing catalysts [8] , non-noble metal catalysts [9][10][11] , and non-metallic catalysts [12][13][14] . In terms of structure, they can be divided into nanoframes [15][16][17] , core-shell structures [18][19][20][21] , and alloy structures [22][23][24][25] , etc. Compared with other structures, the lattice shrinkage effect and surface electron coordination ef-fect in alloy structure could reduce the Pt-Pt atomic spacing and increase the overlap of electron states on Pt.…”

An Fe-N/S-C hybrid electrocatalyst derived from bimetal-organic framework for efficiently electrocatalyzing oxygen reduction reaction in acidic media

“…The excellent tolerance to the methanol poisoning effect results from the much lower ORR potential of the Fe-N/S-C-10% catalyst compared to that required for methanol oxidation (Fig. 9f) [38,39]. Therefore, Fe-N/S-C-10% can be used as an alternative Pt-free catalyst for ORR with high activity, excellent durability and desirable methanol tolerance in acidic media.…”

Core-Shell Structured PtxMoy@TiO2 Nanoparticles Synthesized by Reverse Microemulsion for Methanol Electrooxidation of Fuel Cells

“…So far, many efforts have been done to achieve the above goals. For example, various nanostructured architectures have been investigated including nanoframe, nanocrystal, nanowires, core-shell, and nanoclusters (Lang et al, 2016;Lu et al, 2016;Kwon et al, 2018;Oh et al, 2018;Liu et al, 2019). Among these nanostructures, core-shell structure is very special and has been widely used in electrocatalysis.…”