Highly Open Phosphorized PtNi Nanohexapod/N‐doped Graphene Aerogel for High‐Performance Alkaline Hydrogen Evolution

Phosphorization, highly open branched structure of PtNi nanohexapods (PtNiNHs), anchoring effect of the N-doped graphene aerogel (NGA) to the PtNiNHs, and interconnected porous architecture endow the P-PtNiNH/NGA with accelerated water dissociation kinetics, strong electron interaction for optimal intermediate adsorption, enhanced intrinsic structure stability, and fast mass transport, thus an outstanding comprehensive hydrogen evolution performance.

Abstract

Developing cost-effective, high-efficiency, and stable electrocatalysts for the hydrogen evolution reaction (HER) in alkaline electrolytes is of critical importance for realizing renewable hydrogen technologies. However, the sluggish HER kinetics and unsatisfied stability remain critical challenges for their practical applications. Herein, a hierarchically porous phosphorized Pt-Ni nanohexapod/N-doped graphene aerogel (P-PtNiNH/NGA) constructed by an oxidation-phosphorization-controlled reconfiguration strategy is presented. It enables fast water dissociation kinetics for an abundant supply of hydrogen ions, strong electron interaction for optimal intermediate adsorption, and an excellent anchoring effect of the NGA to avoid the aggregation and Ostwald ripening of the PtNiNHs, thus exhibiting superior activity and exceptional stability toward alkaline HER. The P-Pt₁Ni₂NH/NGA exhibits an ultralow overpotential of 15 mV at a current density of 10 mA cm⁻², a low Tafel slope of 37 mV dec⁻¹, and long-term stability, which are superior to commercial Pt/C. Moreover, the P-Pt₁Ni₂NH/NGA shows a high mass activity of 13.4 mA µg⁻¹ and a large TOF value of 13.5 s⁻¹ at an overpotential of 100 mV, which are 8.8 times and 9.0 times higher than commercial Pt/C (under the same Pt loading of ≈9.1 µg cm⁻²). This work is of high inspiration for catalyst design to obtain ideal alkaline HER performance.