•Liquid exfoliated Sbene nanosheets and electrochemical passivation of Sbene/SPE.•Cathodic measurements with passivated Sbene/SPE in non-deoxygenated solutions.•In-situ preparation of Sbene oxide/PEDOT:PSS nanocomposite via tip sonication.•Advanced detection capabilities of Sbene oxide/PEDOT:PSS/SPE to 4-NT in real samples. Herein, we present the production of antimonene nanosheets and the in-situ preparation of antimonene oxide/PEDOT:PSS nanocomposite via tip sonication of bulk β-phase antimony in water and aqueous PEDOT:PSS, respectively. Nanomaterials were characterized via SEM, EDX, XRD, FT-IR, electrochemical impedance spectroscopy and cyclic voltammetry, while the resulting modified graphite screen-printed electrodes (Sbene/SPE and Sbene oxide/PEDOT:PSS/SPE, respectively) were evaluated in the cathodic determination of 4-nitrotoluene (4-NT), which was used as a model compound, in the presence of dissolved oxygen and in deoxygenated environments. Data document the electrochemical passivation of Sbene/SPE, which, on the one hand, demonstrate a beneficial poor activity towards the oxygen reduction reaction, and on the other hand, enhanced detection capabilities, thus allowing the determination of 4-NT at the micromolar concentration level at non-deoxygenated solutions. As a result, passivated Sbene/SPE show great promise in sensing applications outside of the laboratory where the deoxygenation of the samples is a big obstacle. Moreover, data demonstrate enhanced detection capabilities for Nafion membrane protected Sbene oxide/PEDOT:PSS/SPE, in deoxygenated solutions, which exhibit a detection range from 50 to 5000 nM 4-NT, while achieving an LOD of 16.7 nM (S/N 3). Nafion membrane is essential for the reusability of the electrodes. Sbene oxide/PEDOT:PSS/SPE was also used to the analysis of a spiked river water sample. Recovery was 97.9%.