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 Rct 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%.