Employing Competitive Adsorption and Hollow Nanofiber Strategies toward High-Efficiency Hydrogen Evolution with Ru–Sn/SnO ₂ Heterojunction Catalysts

Electrochemical water splitting is regarded as an efficient method for hydrogen production. Ru is theoretically deemed as an effective electrocatalyst for hydrogen evolution reactions (HERs) in alkaline media owing to its fast hydrolysis kinetics. Nevertheless, its strong OH⁻ adsorption affinity can lead to active site blockage, often resulting in a suboptimal performance in practical HER applications. In addition, electrocatalytic reactions predominantly take place at surface-active sites. In the case of conventional solid catalysts, the core active material remains largely inaccessible due to mass transfer limitations, significantly reducing the overall utilization of active sites. To address these challenges, the work introduces a competitive adsorption strategy and a hollow structure strategy for constructing Ru-Sn/SnO₂ hollow carbon nanofiber electrocatalysts (Ru-Sn/SnO₂ HCNFs). The introduction of Sn/SnO₂ helps to modulate the intense interaction between Ru and OH⁻; OH⁻ adsorption on SnO₂ is more favorable than Ru, thereby successfully mitigating poisoning on Ru. This process also promotes OH⁻ transfer and Ru active site regeneration. Additionally, the specific surface area of Ru-Sn/SnO₂-HCNFs (606.9 m²g⁻¹) is higher than that of the solid fiber of Ru-Sn/SnO₂-CNFs (22.7 m²g⁻¹), highlighting the beneficial role of hollow fibers in enhancing the exposure of active sites. Consequently, Ru-Sn/SnO₂-HCNFs exhibit an outstanding HER performance, achieving remarkably low overpotentials of only 6.8 mV in 1 M KOH and 23.3 mV in 0.5 M H₂SO₄ at 10 mA cm⁻², respectively. This research offers a novel approach on rational design for high-efficiency HER electrocatalysts.