Efficient and stable hydrogen evolution and antibiotic degradation in all-pH-scale water/alkaline seawater using Fe-Co phosphide hollow nanocages fabricated from metallurgical solid waste

Abstract

The utilization of seawater, a plentiful and cost-effective resource, instead of freshwater for H₂ production through electrolysis has garnered significant attention. Herein, we present the synthesis of open-structured Fe-Co phosphide (FCP) nanocages for the overall seawater electrolysis, employing metallurgical solid waste (steel rolling sludge, SRS) as the precursor material. The FCP nanocages demonstrate exceptional catalytic activity for the hydrogen evolution reaction (HER) in all pH scales, achieving performance comparable to that of Pt/C catalysts at high current densities. The electrolyzer assembled with FCP||FCP requires 1.57 and 1.68 V to achieve current densities of 10 and 100 mA cm⁻², respectively. Furthermore, the assembled FCP electrolyzer showcases over 100 h of cycling stability and nearly 100% Faradaic efficiency. Crucially, it can be powered by commercially available silicon solar panels, operating under an intensity of 100 mW cm⁻², and by wind-driven sources, rendering it highly promising for real-world applications. The seawater hydrogen evolution system coupled with levofloxacin (LEV) degradation was constructed for the first time. The oxidation potential of LEV oxidation reaction (LEVOR) was significantly lower than that of oxygen evolution reaction (OER), indicating that the LEV degradation reaction occurred preferentially and achieved a removal efficiency of 98.57% within 60 min. This study provides effective strategies for valorizing SRS and offers insights into the fabrication of high-performance catalysts.