In this work the possibility was investigated to synthesize in-situ silver nanoparticles (AgNP) on graphene oxide (GO) surface without commonly used additional reducing or alkalizing agents or increased temperature. Using diverse microscopic (AFM, TEM) and spectroscopic methods, it was proved that very small AgNPs were formed on GO by simple incubation for 2 hours a mixture of GO dispersion and AgNO3. The prepared nanomaterial (GO_Ag) was also assessed using electrochemical methods and it exhibited electrochemical behavior similar to GO_Ag nanomaterial prepared with a help of citric acid as a reducing agent. Furthermore, it was found that i) electrochemical reduction of the GO_Ag on electrode surface decreased the voltammetric response even though this step has increased the surface conductivity and ii) GO_Ag can be employed for sensing of chlorides with detection limit of 79 M and a linear range up to 10 mM. It could also provide electrochemical response toward chloroacetanilide herbicide metazachlor. Hence, the reducing capabilities of GO were proved to be applicable for insitu synthesis of metal nanoparticles with the highest possible simplification and the as-prepared nanomaterials could be employed for fabrication of different electrochemical sensors.

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An investigation was made into polymeric films based on polyvinylpyrrolidone (PVP) as the matrix, in combination with synthetic zeolite and dried or pyrolyzed biocarbon (biochar). The films were prepared by the casting method, and their properties were variously analysed (optical microscopy, FTIR analysis, differential scanning calorimetry, mechanical properties, water solubility, water uptake). Evaluation also encompassed the biological decomposition of the films in the soil environment and their influence on the growth of Sinapis alba. Optical microscopy indicated the particles of the fillers were almost completely evenly distributed in the polymer matrix, therein forming networks randomly. Since the space between the particles decreased as particle content increased, raising the content of the fillers brought about more compact networks. The IR spectra for the films proved the occurrence of hydrogen bonding between the PVP and synthetic zeolite. The processing and mechanical properties of the prepared polymeric films were acceptable. Water solubility and the water uptake of the films were satisfactory regarding handling and further use. Respirometric tests indicated a positive effect by the biocarbon on the biodegradation of the tested films. The proposed combination of synthetic zeolite and biocarbon fillers positively influenced the germination rate of Sinapis alba, while the polymer matrix (PVP) did not hinder further growth. Observations and testing led to the conclusion that the materials based on PVP with fillers (synthetic zeolite/ biocarbon) have the potential for agricultural utilization.

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In this work silver nanoparticles (AgNPs) were in situ synthesized on surface of graphene oxide (GO) and Ti3C2TX MXene at room temperature and without any reducing agent. The prepared GO_AgNPs and MX_AgNPs nanomaterials were deposited on electrodes and applied for voltammetric sensing of pesticide metazachlor. The chosen analyte underwent electrochemical reduction readable as faradaic current and identified as the electrochemical reductive dechlorination. It was found that GO_AgNP (electrochemically reduced to ErGO_AgNP before measurements) was more efficient catalyst of the observed dechlorination than MX_AgNP, even though it contained approximately 10-fold lower amount of silver. The smaller size of AgNP achieved with GO was the most probable reason. When the metazachlor sensing properties of the nanohybrid-modified electrodes were investigated, the linear range and the limit of detection of 37–1123 μM and 27 μM, respectively, were observed for ErGO_AgNP while only 37–375 μM and 40 μM for MX_AgNP. The ErGO_AgNP nanohybrid was more convenient also for metazachlor detection in alkali leachate of real soil samples, probably as the result of antifouling effect of ErGO. Although there are conventional instrumental analysis methods for sensing orders of magnitude lower concentrations of metazachlor, in this work it is for the first time shown that the AgNP-based nanohybrid efficiently catalyse the electrochemical dechlorination applicable for detection of this frequently used pesticide.