Direct-laser-writing of electrochemiluminescent electrode on glassy carbon for iodide sensing in aqueous solution

•Stable and binder-free ECL electrode was fabricated by in-situ direct-laser-writing.•ECL emission was obviously enhanced by ultrasonication with good reproducibility.•Sensitive ECL detection of iodide ion is achieved with acceptable selectivity. Simple and scalable construction of high-efficient solid-state electrochemiluminescence (ECL) electrode has attracted a lot of attention. Herein, using CdS as a model ECL emitter, one-step laser-scribing technique was successfully explored as an in situ and straightforward solid-phase-transition approach for the facile construction of binder-free ECL electrode. The suitable laser-scanning of Cd2+-doped polyethersulfone film on glassy carbon (GC) leads to the synchronous generation of laser-induced graphene (LIG) and laser-induced CdS (LI-CdS) hybrids anchored on GC surface (LI-CdS-G@GC). The cathodic ECL properties of LI-CdS-G@GC electrodes before and after an ultrasonication process (LI-CdS-G@GCUS) were investigated using peroxodisulfate as co-reactant. Notably, 60-fold higher ECL emission with excellent stability and reproducibility was obtained from the resultant LI-CdS-G@GCUS as compared to untreated LI-CdS-G@GC due to the ultrasonication-assisted removal of blackbody effect of LIG. Ultimately, the as-prepared LI-CdS-G@GCUS electrode with rapid and reliable ECL response was employed to construct an ECL sensor for the detection of iodide ions, showing a wide linear range of 10.0 nM–2500 nM and a low detection limit of 4.0 nM with acceptable selectivity. This work not only expands the application range of LIG but also provides a guideline for the facile design and scalable fabrication of sensitive ECL sensing interface.