High electrocatalytic activity of crystallization-modulated ordered PtCu3/C nanoalloy catalysts for oxygen reduction reaction

Ordered platinum intermetallic alloys, due to their structured chemical composition and high activity, have been considered as one of the ideal electrocatalysts for fuel cells. Ensuring the controlled structure of alloy nanoparticles (NPs) is a prerequisite for obtaining highly active platinum-based alloy catalysts. In this study, we employed different pH adjusters to modulate the crystallization of Pt alloy NPs in catalysts. By balancing the competition between precipitation and complexation reactions in the solution, the size and structure of platinum alloy particles can be effectively adjusted. Utilizing NH 3 ·H 2 O as a pH adjuster, we synthesized an ordered PtCu 3 alloy catalyst with a particle size of 3.3 nm. This catalyst exhibits a half-wave potential of 0.945 V and a mass activity of 1.061 mA µg Pt –1 , which is 11.7 times higher than that of commercial 20 % Pt/C (TKK). This enhancement in catalytic activity is attributed to the introduction of transition metal copper atoms into the catalyst, forming an ordered intermetallic structure that induces compressive strain. This strain lowers the d-band center, weakens the adsorption of oxygen-containing intermediates, which strengthen catalytic activity. Therefore, by adjusting the morphology of metal precursors to improve the microstructural form and state of the catalyst, the oxygen reduction activity can be significantly enhanced.