Simples fabrication of hierarchical NiCoSe₄ nanorods grown on carbon nanofibers as excellent electrocatalysts for tryptophan oxidation

In this study, a simple approach is established to fabricate NiCoSe₄ nanorods grown onto carbon nanofiber (CNF) skeletons by combining electrospinning and a hydrothermal process. We achieved the rapid and ultrasensitive electrocatalytic sensing of tryptophan (Trp) in 0.1 M KOH by using intrinsically metallic NiCoSe₄ anchored on CNFs as an alternative working electrode material. Benefiting from the large surface area due to rich defect active sites and the high electrocatalytic behavior of NiCoSe₄ with CNF, the fabricated sensor exhibits a lower electron-transfer resistance of R_ct 92 Ω with respect to the CNF–NiCo and CNFs electrodes. The results of voltammetric technique confirmed that the CNF–NiCoSe₄-GCE showed higher anodic peak intensity and a lower anodic potential for Trp detection than CNFs-GCE and CNF–NiCo-GCE electrodes since the integration of sp² carbon on the surface of the CNFs and bimetallic selenides improves the sensing performance. The amperometric I-t curve showed a linear response in the Trp concentration range of 5–95 nM and a detection limit of 0.68 nM at low potential of 0.4 V vs. Hg/HgO. The CNF–NiCoSe₄-GCE was successfully utilized for the electrocatalytic monitoring of Trp from human serum, milk, and tomato juice samples with a recovery of 95.4–105.5%.