An anti-fouling electrocatalytic interface based on Pt nanoparticles anchored on Fe, N, S co-doped hierarchically porous carbon for sensitive electrochemical determination of indole-3-acetic acid

In this study, we synthesized Fe, N, S co-doped hierarchically porous carbon (Fe-CSK-PCP) with a high specific surface area of 1826.34 m 2 /g and a pore volume of 1.14 cm 3 /g. This material was prepared using discarded lotus seedpods as a carbon source, potassium hydroxide (KOH) as an activator, potassium ferricyanide as both an activator and graphitization promoter, thiourea as a source of N and S dopants, and cetyltrimethylammonium bromide (CTAB) as a pore-enlarging agent. Platinum nanoparticles (PtNPs) were subsequently loaded onto the Fe-CSK-PCP surface via wet impregnation. The enhanced porosity, increased pore size, and heteroatom doping of the Fe-CSK-PCP support have significantly promoted the loading content and dispersion of PtNPs, consequently creating an abundance of active sites. Meanwhile, the hierarchical pore structure has improved the diffusion of analyte and the desorption of oxidation product. Therefore, the fabricated PtNPs/Fe-CSK-PCP sensor exhibited exceptional fouling resistance and electrocatalytic performance in indole-3-acetic acid (IAA) detection, demonstrating a high sensitivity (2.32 μA/μM) and a low detection limit (21.67 nM, S/N = 3) over a wide linear range (0.3–20 μM). This sensor was successfully applied to determine IAA in apple juice samples with satisfactory recoveries.