Monika Skruodiene

This study investigates the photoelectrochemical (PEC) performance of molybdenum-doped bismuth vanadate (Mo-doped BiVO₄) and its heterojunction with the BiOCl layer in glucose and urea sensing. Photoelectrochemical analyses, including cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), revealed that the formation of a heterojunction enhanced charge carrier separation. The impact of the interaction between the surface of the photoanode and analytes on sensing performance was systematically evaluated. Among the tested configurations, Mo-doped BiVO₄ exhibited superior glucose sensing with a limit of detection (LOD) of 0.173 µM, while BiVO₄/BiOCl demonstrated an LOD of 2.474 µM. In the context of urea sensing, Mo-doped BiVO₄ demonstrated an LOD of 0.656 µM, while BiVO₄/BiOCl exhibited an LOD of 0.918 µM. Notably, despite the enhanced PEC activity observed in heterostructured samples, Mo-doped BiVO₄ exhibited superior sensing performance, attributable to good interaction with analytes. The photocurrent response trends—an increase with glucose concentration and a decrease with urea concentration—were attributed to oxidation and adsorption phenomena on the photoanode surface. These findings underscore the critical role of photoanode surface engineering in advancing PEC sensor technology, paving the way for more efficient environmental and biomedical applications.

This study presents the findings of an investigation into the characteristics and capabilities of BiVO₄ and Mo-doped BiVO₄ coatings for the detection of diclofenac (DCF). In this study, a neutral sodium sulfate electrolyte and an alkaline sodium borate buffer were selected, and a range of potentials were employed to ascertain the impact of diverse conditions on the sensing performance of diclofenac. The introduction of Mo-doping had a profound impact on the photoelectrochemical response of the BiVO₄ coating. However, it was observed that Mo-doping resulted in an increase in the adsorption of diclofenac oxidation products on the surface of the photoanode, which in turn led to a negative blocking effect. To evaluate the structural and morphological properties of the coatings, X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), and energy dispersive analysis (EDX) were conducted. The photoelectrochemical properties were evaluated through the use of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry (CA). An increase in the photocurrent density of BiVO₄ was observed in response to an increase in the concentration of diclofenac within a range of 0.1 to 1 mg L⁻¹ during the sensing experiments. However, at higher concentrations, saturation of diclofenac was observed at the photoelectrode/electrolyte interface. The results of selectivity experiments demonstrated that the nature of the electrolyte has a significant impact on the selectivity of designed photoelectrochemical sensors.

Environmentally friendly alternatives to chromium—phosphate/molybdate and cerium-modified phosphate/molybdate conversion coatings—were deposited on a carbon steel surface. Different surface analytic techniques were applied to obtain complementary information on the composition, element distribution morphology and inner structure of the coatings in order to establish the relationship between coating properties and corrosion performance. The higher protective and stronger self-healing abilities were found for phosphate/molybdate/cerium conversion coating deposited in a sulphate-containing solution. The protective barrier strength was found to be related with certain aspects of the coating morphology such like homogeneous distribution of fine crystallites and, hence, lower number of structural defects. The self-healing ability depended on both, the composition (higher amount of Ce(IV)) and micro-structural characteristics, such as defectiveness, of the conversion layer.