ZIF‐Mg(OH)₂ Dual Template Assisted Self‐Confinement of Small PtCo NPs as Promising Oxygen Reduction Reaction in PEM Fuel Cell

Abstract

Traditional calcination usually causes sintering of Pt, which diminishes Pt exposure in proton exchange membrane fuel cell (PEMFC) electrodes. In the present work, a facile self‐confined method for synthesizing highly dispersed PtCo‐alloy on Co, N co‐doped mesoporous carbon (PCN‐MC) is developed via a dual‐template strategy. Owing to the co‐confined effect of Zn in the bimetallic zeolite‐based imidazolate framework (ZIF) and Mg(OH)2 template, ultra‐fine 2.7 nm PtCo‐alloy with 2–3 atomic‐layer Pt‐skin nanoparticles are obtained. By adjusting the Co/Zn feeding‐ratio in the bimetallic ZIF at 8/7, the alloying degree and nanoparticle size are optimized to achieve an outstanding oxygen reduction reaction activity with a high mass activity (MA) of 0.956 A mgPt−1 in 0.1 m HClO4, about 7.5‐fold of that of commercial Pt/C. Furthermore, notable durability is also achieved with 81% retention of the initial MA after 30k cycles conducted between 0.6–1.0 V (versus reversible hydrogen electrode). These features are also verified by a H2–Air fuel cell test with an excellent combination of mass activity, power density, and durability. This strategy provides a feasible route for the large‐scale synthesis of highly‐dispersed PtCo‐alloy catalysts.

Towards ultralow platinum loading proton exchange membrane fuel cells

“…37 In addition, rational surface modification or anchoring can strengthen the catalyst-support interaction and prevent catalyst nanoparticles from coalescence. [79][80][81][82] Lin et al 79 anchored PtCo catalysts on honeycombed graphene that achieved 90% retention of initial mass activity after 20 000 voltage cycles, while Chen et al 80 anchored PtCo catalysts on Co and N co-doped mesoporous carbon that achieved 81% retention of initial mass activity after 30 000 voltage cycles. Kumar et al 81 prepared the MEA using the Pt supported on a tantalum-modified titanium dioxide catalyst that achieved a low voltage loss of 23 mV at 0.4 A cm À2 after accelerated stability tests, which was over an order of magnitude lower than the loss observed in the Pt/C MEA.…”

Pt Alloy Nanocrystal Catalysts: Diminishing Sizes and Improving Stability

“…The catalyst exhibited high ORR catalytic activity and stability, and the mass activity was more than 3 times that of the commercial Pt/C catalyst. Shen et al 21 prepared a highly dispersed 2.7 nm PtCo alloy on Co, N codoped mesoporous carbon (PCN-MC) using a dual-template method. By optimizing the electronic and geometric structures of the nanoparticles to achieve efficient ORR activity, the catalyst has a high mass activity of 0.956 A mg Pt −1 , which is about 7.5 times higher than that of commercial Pt/C.…”

The enhancement in the performance of ultra-small core–shell Au@AuPt nanoparticles toward HER and ORR by surface engineering

“…Pt-based catalysts are still the most potential catalysts with excellent performance toward the hydrogen evolution reaction (HER) and the oxygen reduction reaction (ORR) in acidic media. [1][2][3][4][5][6] To further boost their catalytic performance, many efforts have been made to synthesize Pt-based catalysts by controlling their sizes, [7][8][9][10][11] shapes, [12][13][14][15][16] structures, [17][18][19][20][21][22][23] and tuning surface compositions. [24][25][26][27][28][29][30] For instance, ultra-small core-shell Au-Pt nanoparticles (USCS Au@AuPt NPs) with Au-rich cores and Pt-rich shells previously reported in our work exhibit excellent electrocatalytic performance toward the HER and ORR in acidic media due to the higher electrochemically active surface area (ECSA) resulting from their small sizes and electronic effect between Pt and Au.…”