Rhenium-dispersed fibrous polyaniline coupled superaerophobic support as hydrogen/oxygen evolving electrodes

• Fibrous polyaniline was grown on nickel foam via substrate-induced polymerization. • Ultrasmall rhenium particles were coupled to the fibrous polyaniline functionalized nickel foam. • Rhenium particles with the size of 2–4 nm was synthesized via chemical reduction method. • Fibrous polyaniline showed high surface area and enhanced the rhenium growth density. • The binder-free catalyst demonstrated remarkable hydrogen and oxygen evolving properties. Developing cost-effective metal catalyst with high catalytic efficiency and durability for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) has become a primary objective in water electrolysis technology. Herein, we report the synthesis of rhenium particle-coupled fibrous polyaniline-functionalized nickel foam (Re@ fib -PANi@NF) as a bi-functional catalyst for HER and OER. The fibrous PANi layers, possessing a high surface area, provided abundant active sites, thereby enhancing the nucleation and growth density of Re particles. The open porous architecture of the fibrous PANi preserved the inherent porosity of the NF, ensuring additional catalytic contribution from the substrate. More importantly, the interfacial fibrous PANi, enriched with nitrogen functionalities, facilitated strong coupling interactions between the Re particles and the NF substrate, positively influencing both the charge transfer kinetics and the structural stability of the catalyst. Leveraging these structural and compositional advantages, the Re@ fib -PANi@NF catalyst demonstrated remarkable HER activity, with an overpotential of 530 mV at a current density of 700 mA cm -2 , a Tafel slope of 29 mV dec -1 , and sustained current output over prolonged operation. Furthermore, the Re@ fib -PANi@NF catalyst exhibited outstanding OER activity, requiring only 410 mV at a current density of 800 mA cm -2 , maintained a stable voltage profile up to 50 h without any observable voltage decay. This study highlights the importance of structural engineering the interfacial layer to effectively couple the Re metal particles with the NF substrate. This strategy offers a promising pathway for integrating other advanced metal particles with various catalyst supports for broad catalytic applications.