Prussian blue nanocubes growth by electrochemical deposition on sulfur-doped graphene as nanozyme: Optimization and application in the field of environmental sensors

• Electrochemically synthesized PB nanocubes with 50 nm mean size. • Miniaturized design of S-Gr and PB nanocubes on SPCE for real-world applications. • PB nanocubes as nanozymes for stable, cost-effective, on-site monitoring. • Superior performance of 1.6 nM as detection limit and 1.05 µA × µM⁻¹ sensitivity. • Addressing environmental concerns about organic pollutants by sensitive HQ detection. This study presents the electrochemical deposition of Prussian blue (PB) nanomaterial on top of a sulfur-doped graphene (S-Gr) drop-casted on a screen-printed carbon working electrode (SPCE) for the development of environmental sensing devices with higher sensitivity to phenolic pollutants. The deposition process was optimized by carefully controlling the deposition parameters to achieve PB nanocubes (PBNCs) with an average size of ∼ 50 nm. The resulting nanocomposite material, PBNCs-S-Gr, was evaluated for the electrooxidation of hydroquinone (HQ), a widely studied phenolic compound, to demonstrate its catalytic activity in oxidizing phenolic substrates, effectively mimicking the enzymatic behavior of natural peroxidase. The obtained PBNCs-S-Gr/SPCE presented a calculated limit of detection (LOD) of 0.33 nM and an increased sensitivity of 1.5 µA × M -1 , with a wide linear concentration range from 0.001 to 10 µM for HQ detection. Notably, the recovery values obtained for surface water samples fall within the range of 92.1 % to 98.9 %, indicating strong agreement with results derived from the standard method, ultra high-performance liquid chromatography system with diode array detection (UHPLC-DAD).