The control of glucose concentration is a crucial factor in clinical diagnosis and the food industry. Electrochemical biosensors based on reduced graphene oxide (rGO) and conducting polymers have a high potential for practical application. A novel thermal reduction protocol of graphene oxide (GO) in the presence of malonic acid was applied for the synthesis of rGO. The rGO was characterized by scanning electron microscopy, X-ray diffraction analysis, Fourier-transform infrared spectroscopy, and Raman spectroscopy. rGO in combination with polyaniline (PANI), Nafion, and glucose oxidase (GOx) was used to develop an amperometric glucose biosensor. A graphite rod (GR) electrode premodified with a dispersion of PANI nanostructures and rGO, Nafion, and GOx was proposed as the working electrode of the biosensor. The optimal ratio of PANI and rGO in the dispersion used as a matrix for GOx immobilization was equal to 1:10. The developed glucose biosensor was characterized by a wide linear range (from 0.5 to 50 mM), low limit of detection (0.089 mM), good selectivity, reproducibility, and stability. Therefore, the developed biosensor is suitable for glucose determination in human serum. The PANI nanostructure and rGO dispersion is a promising material for the construction of electrochemical glucose biosensors.

The melt of H₃BO₃ was used to reach a controllable reduced graphene oxide (rGO) synthesis protocol using a graphene oxide (GO) precursor. Thermogravimetric analysis and differential scanning calorimetry (TG/DSC) investigation and scanning electron microscopy (SEM) images have shown that different from GO powder, reduction of GO in the melt of H₃BO₃ leads to the formation of less disordered structure of basal graphene planes. Threefold coordinated boron atom acts as a scavenger of oxygen atoms during the process of GO reduction. Fourier-transform infrared (FTIR) spectra of synthesized products have shown that the complex of glycerol and H₃BO₃ acts as a regioselective catalyst in epoxide ring-opening reaction and suppress the formation of ketone C=O functional groups at vacancy sites. Thermal treatment at 800 °C leads to the increased concentration of point defects in the backbone structure of rGO. Synthesized materials were tested electrochemically. The electrochemical performance of these materials essentially differs depending on the preparation protocol. The highest charge/discharge rate and double-layer capacitance were found for a sample synthesized in the melt of H₃BO₃ in the presence of glycerol and treated at 800 °C. The effect of optimal porosity and high electrical conductivity on the electrochemical performance of prepared materials also were studied.

In this work, graphite intercalation compounds (GICs) were synthesized using three different oxidizers: (NH₄)₂S₂O₈, K₂S₂O₈, and CrO₃ with and without P₂O₅ as a water-binding agent. Furthermore, the samples obtained were heat-treated at 800 °C. Specimens were characterized by optical microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), and scanning electron microscopy (SEM). The correlation between different characteristic parameters of the Raman analysis has shown that the use of CrO₃ results in a much higher structural disorder compared to the products obtained using persulfate oxidizers. Narrowing the correlation set revealed that minimal defect concentration can be reached by using K₂S₂O₈, while the use of (NH₄)₂S₂O₈ causes a slightly higher concentration of defects. It was also established that the additional use of P₂O₅ can help to achieve more effective intercalation and has a positive effect on the formation of the stage I GIC phase. After heat treatment, the intercalated products mostly return to a graphite-like structure; however, the samples obtained with CrO₃ stand out with the most significant changes in their surface morphology. Therefore, analysis suggests that GICs obtained using persulfate oxidizers and P₂O₅ could be a candidate to produce high-quality graphene or graphene oxide.

In the present work, beta-calcium pyrophosphate (β-Ca₂P₂O₇) was investigated as a potential adsorbent for the removal of heavy metal ions from water. Single-phase β-Ca₂P₂O₇ powders were synthesized by a simple, scalable and cost-effective wet precipitation method followed by annealing at 800 °C, which was employed for the conversion of as-precipitated brushite (CaHPO₄∙2H₂O) to β-Ca₂P₂O₇. Physicochemical properties of the sorbent were characterized by means of X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR), thermal analysis (TGA/DSC), scanning electron microscopy (SEM) and low temperature adsorption–desorption of nitrogen (BET method). The synthesized powders consisted of porous plate-like particles with micrometer dimensions. Specific surface area calculated by the BET method was found to be 7 m² g⁻¹. For the estimation of sorption properties, the aqueous model solutions containing different metal ions (Al³⁺, Cd²⁺, Co²⁺, Cu²⁺, Fe²⁺, Mn²⁺, Ni²⁺, Pb²⁺, Sn²⁺, Sr²⁺ and Zn²⁺) were used. The adsorption test revealed that β-Ca₂P₂O₇ demonstrates the highest adsorption capacity for Pb²⁺ and Sn²⁺ ions, while the lowest capacity was observed towards Sr²⁺, Ni²⁺ and Co²⁺ ions. The optimal pH value for the removal of Pb²⁺ ions was determined to be 2, which is also related to the low solubility of β-Ca₂P₂O₇ at this pH. The adsorption capacity towards Pb²⁺ ions was calculated as high as 120 mg g⁻¹.