This work presents a comparative study of two photoelectrochemical (PEC) sensing configurations for the detection of levodopa: a conventional three‐electrode PEC system and a fully PEC (full‐PEC) cell. The conventional setup employs a fluorine‐doped tin oxide (FTO) electrode modified with a bismuth oxyiodide and barium titanate perovskite composite (BiOI@BaTiO 3 /FTO) as the working electrode. In contrast, the full‐PEC configuration integrates two photoelectrodes, coupling the BiOI@BaTiO 3 /FTO electrode with a copper(II) oxide‐modified FTO electrode (Cu 2 O/FTO). The morphological, spectroscopic, and structural characteristics of the PEC materials were evaluated using scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDS), and X‐ray diffraction (XRD). Rietveld refinement of the XRD data for the BiOI@BaTiO 3 composite confirmed its composition and crystal structure, revealing approximately 74.1 at.% BaTiO 3 and 25.9 at.% BiOI. The analysis further indicated that BaTiO 3 crystallizes in a tetragonal structure (space group P4/mmm, No. 123), while BiOI adopts a tetragonal space group P4/nmm (No. 129). In addition, SEM micrographs revealed a rough surface morphology with flake‐like BiOI particles deposited on the larger BaTiO 3 grains. Under optimized conditions, the conventional PEC platform presented a sensitivity of 0.0118 µA L µmol −1 , while the self‐powered PEC system exhibited a significantly higher sensitivity of 0.05562 µA L µmol −1 . The full‐PEC system based on the BiOI@BaTiO 3 /FTO and Cu 2 O/FTO photoelectrodes was successfully utilized for the detection of levodopa in pharmaceutical samples. These results underscore the promise of the full‐PEC systems for sensitive and selective levodopa detection, offering a potential alternative to conventional PEC configurations.
BORGES et al. (Fri,) studied this question.