Atomic-scale engineering of Fe–Cu nanoparticles on amine-functionalized silica: CNT-driven synergy for ultra-efficient hydrogen evolution

Abstract

Emphasizing a breakthrough in material synergy and synthesis strategies, this work provides a new catalyst design for high-efficiency electrolytic water splitting. The novelty is in the development of a hierarchical Fe/Cu@silica-CNT composite, whereby exact anchoring of Fe³⁺/Cu²⁺ ions is enabled by silica functionalization with N-(3-(trimethoxysyl)propyl)ethylenediamine, consequently guaranteeing atomic-level metal distribution and preventing nanoparticle aggregation. A significant improvement over conventional deposition techniques resulted from subsequent chemical reduction, producing ultra-small, stable Fe/Cu nanoparticles (5 nm) directly grafted onto silica. The use of multi-walled carbon nanotubes (CNTs) generated a three-dimensional conductive network, which simultaneously optimized charge transfer and achieved nanoparticle dispersion. Extensive characterization (FE-SEM, EDX, XPS, and BET) confirmed that the high-density active sites at Fe/Cu–SiO₂ interfaces, coupled with CNT-induced electron delocalization, validate the uniqueness of the architecture. Under acidic conditions, electrochemical testing revealed remarkable hydrogen evolution reaction (HER) performance with a record-low Tafel slope of 34 mV dec⁻¹ and an overpotential reduction of 120 mV against bare CNTs. Fe–Cu electronic interactions and CNT-mediated mass transport resulted in a 4.3-fold increase in exchange current density that the catalyst achieved relative to its monometallic counterparts. This work presents a transforming solution for scalable green hydrogen generation using a creative dual-engineering approach, molecular-scale metal anchoring, and a nano-architecture conductive support, thus solving major obstacles in catalyst durability and activity.