Freestanding WS₂-MWCNT Nanocomposite for Electrochemical Detection of Contaminants of Emerging Concern─Perfluorooctanoic Acid “A Forever Chemical” and Supercapacitor Applications

Perfluorooctanoic acid (PFOA) presents a significant environmental challenge due to its persistent nature and resistance to degradation. Our research offers an innovative solution by an ingenious combination of WS2 and multiwalled carbon nanotubes (MWCNTs) to synthesize a versatile, freestanding WS2-MWCNT electrode for electrochemical sensing of PFOA and as a supercapacitor device. This electrode demonstrated outstanding electrochemical sensing capabilities, exhibiting a detection limit of 2.404 pM for PFOA. The interference study revealed that the electrode has a high degree of selectivity toward PFOA. Real-world applicability was assessed through testing tap water and various food samples, yielding recovery rates within 96.53–102.11%, underscoring the viability of the WS2-MWCNT electrode in practical applications. Furthermore, the WS2-MWCNT displayed excellent supercapacitor performance. The fabricated device displayed a specific capacitance of 134.72 F/g at a current density of 6 A/g and showcased a high energy density of 46.15 Wh/kg at a power density of 500 W/kg. Furthermore, the WS2-MWCNT exhibited good durability, with a capacitance retention rate of 89.14% even after undergoing 10 000 cycles.These findings highlight the multifunctional electrochemical applications of the WS2-MWCNT NCs, attributed to the synergistic impact of WS2 and MWCNTs to achieve suitable specific capacitance and susceptible detection of forever chemicals.