Confined and rapid synthesis of Pt-based transition metal nanoalloys on hierarchically porous carbon nanofibers for efficient HER/ORR electrocatalysis

Abstract

Carbon-supported Pt-based nanoalloys are promising catalysts for both the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR). However, traditional synthesis methods often involve limited anchoring sites and prolonged high-temperature annealing, leading to enlarged particle sizes and reduced electrocatalytic performance. Herein, we develop a spatial confinement strategy combined with rapid microwave heating to synthesize ultrafine Pt-based transition metal alloy nanoparticles (sub-10 nm) on hierarchically porous carbon nanofibers (Pt–M-PCNFs, where M = Fe, Co and Ni). The spatial confinement effect of PCNFs with ordered micro-, meso-, and macropores is key to achieving high dispersion of alloy nanoparticles, while maximizing active site exposure, enabling fast mass transfer, and ensuring structural stability. As a result, the prepared Pt₃Ni-PCNFs exhibit a low HER overpotential of 9 mV to deliver 10 mA cm⁻² in 1.0 M KOH, excellent acidic ORR activity with a high half-wave potential of 0.914 V, and robust stability. Theoretical calculations reveal that strong Pt 5d–Ni 3d orbital electronic interactions shift the d-band center of Pt, reducing the adsorption energy of *H and *OH intermediates, thus significantly enhancing intrinsic activity toward the HER and ORR. This work opens a new avenue for the design and synthesis of efficient catalysts for energy-related applications.