PtNi multi-branched nanostructures as efficient bifunctional electrocatalysts for fuel cell

Abstract

Fuel cells are highly efficient conversion devices to alleviate energy crisis and environmental pollution, but still encounter technical challenges to further improve catalytic efficiency of Pt-based electrocatalysts. In this work, PtNi multi-branched nanostructures (PtNi MBNs) were successfully prepared by a simple and economical one-step solvothermal method. The average diameter of the branches is about 9 nm, with numerous atom steps and Pt-rich surface. The prepared electrocatalyst shows excellent bifunctionality in acidic electrolytes, catalyzing both oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR). The half-wave potential of 0.966 V for ORR is much higher than that of commercial Pt/C (0.931 V), and only decreases 14 mV after 8,000 cycles. For MOR, the specific activity of PtNi MBNs is 18.1 A m-2 Pt, better than that of commercial Pt/C (7.8 A m-2 Pt), indicating an optimal intrinsic activity. The remarkable bifunctionality of PtNi MBNs is attributed to the exposed electrochemical surface area, abundant atomic steps, and Pt-rich surface provided by the unique multi-branched nanostructure. This facile preparation technique offers a promising application for designing high-performance electrocatalyst for acid direct methanol fuel cell in the future.

Branching phenomena in nanostructure synthesis illuminated by the study of Ni-based nanocomposites

“…8,9 All of these intriguing biological, chemical, and physical properties depend upon the nanostructures' branched morphologies, but the morphology control can only garner limited support from the current understanding of the branching mechanism. [10][11][12][13][14] Hence a deeper mechanistic understanding is called for. Specifically, the intrinsic complexity, i.e., instability-induced symmetry breaking and non-equilibrium process-induced kinetic trapping, are not sufficiently understood to predict the timing and extent of branching.…”

“…8,9 All of these intriguing biological, chemical, and physical properties depend upon the nanostructures' branched morphologies, but the morphology control can only garner limited support from the current understanding of the branching mechanism. 10–14 Hence a deeper mechanistic understanding is called for. Specifically, the intrinsic complexity, i.e.…”