Hot Injection Assisted Electronically Modulated Twin and Grain Boundary Rich Sub‐2 nm Pt₃Co Alloy Resistant to Phosphate Ion for PEMFCs

Modulation of the electronic d-band center, structural defects (line defects), and particle size of Pt₃Co alloy electrocatalyst have huge significance in elevating its electrochemical oxygen reduction reaction activity. Deviating from traditional high-temperature strategies, the current work focuses on ripening these benefits by implying a simple economically viable hot-injection-assisted modified polyol process. A conclusive control over decrementing particle size starting from 2.7 to 1.3 nm, an increasing degree of strain (twin boundary), and shifting of the d-band center away from the Fermi level are obtained via varying the temperature to which the solution is injected. The catalyst prepared via the injection at 200 °C (Pt₃Co_{(1.3 t,g-b)}/fVC-200) has delivered an electrochemical surface area of 84 m² <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics><mml:mrow><mml:mspace></mml:mspace> <mml:msubsup><mml:mi>g</mml:mi> <mml:mi>Pt</mml:mi> <mml:mrow><mml:mo>-</mml:mo> <mml:mn>1</mml:mn></mml:mrow> </mml:msubsup> </mml:mrow> <mml:annotation>$\;{\mathrm{g}}_{{\mathrm{Pt}}}^{ - 1}$</mml:annotation></mml:semantics> </mml:math> with the onset and half-wave potentials of 0.980 and 0.858 V, respectively, versus RHE and a limiting current of -6.0 mA cm^-2 with stability till 20k cycles. In the high-temperature proton exchange membrane fuel cell Pt₃Co_{(1.3 t,g-b)}/fVC-200-based cell has outperformed Pt/C rendering 600 mWcm^-2 under H₂-Air compared to 529 mWcm^-2 of Pt/C with 20% lower Pt loading and double the stability due to enhanced resistance toward phosphoric acid for accelerated voltage cycling. A similar enhancement is seen while employing the catalyst for low-temperature fuel cells.