• • Fe2.5/Ni5–ACF achieved 99.88% conversion of 4-NP within 10 min using 0.26 mol L−1 NaBH4, outperforming several reported catalysts (e.g., AgNi/PC@Mn NPs: >99% in 16 min; Ni/Co/Cu–ACF: 98.5% in 10 min) and demonstrating superior kinetics for wastewater treatment.
• • The coal tar pitch-based ACF support exhibited a specific surface area of 1847 m2/g with micropores accounting for 97.6% of total pore volume, providing abundant active sites for metal nanoparticle dispersion and enhancing catalytic activity through adsorption synergy.
• • Optimal synthesis conditions were identified: reaction temperature 45 °C, 4-NP concentration 2.5 mmol L−1, and Fe3+:Ni2+ molar ratio of 1:2 (total 7.5 mmol L−1), yielding a catalyst with an average nanoparticle diameter of ~100 nm and stable recyclability over five cycles.
• • The hydrothermal–calcination method enables cost-effective loading of non-precious bimetallic Fe–Ni nanoparticles onto ACFs, offering a scalable alternative to precious metal catalysts for industrial 4-NP reduction, with potential for treating high-strength wastewater.