In the present study, two types of graphene quantum dots (GQDs) were investigated: green-emitting (G-GQDs) and blue-emitting (B-GQDs). Physicochemical characterisation was performed using transmission electron microscopy (TEM), zeta potential, and hydrodynamic radius measurements to evaluate the morphology, particle size, aggregation behaviour, and colloidal stability of the GQDs in both water and cell culture medium. G-GQDs exhibited superior colloidal stability and more uniform dispersion than B-GQDs, whereas both types showed reduced aggregation and surface charge in cell culture medium due to protein corona formation. Toxicological characterisation was performed using an in vitro human hepatocellular carcinoma (HepG2) 3D spheroid model, with GQDs exposures up to 250 µg/mL (100 µg/cm2). Cytotoxicity was measured using the CellTiter-Glo luminometric assay, while genotoxicity was evaluated by the comet assay and flow cytometric analysis of γH2AX and phosphorylated histone H3 (p-H3) after 24 h of exposure. Both GQDs induced dose-dependent cytotoxic effects in HepG2 spheroids. At non-cytotoxic concentrations, a dose-dependent increase in DNA damage was observed, as determined by the comet assay. However, no evidence of DNA double-strand breaks (γH2AX) or elevated p-H3 levels was detected, suggesting the absence of clastogenic and aneugenic activity. The observed DNA single-strand breaks may be partly attributed to reactive oxygen species induction. These results indicate that, although GQDs induced cytotoxicity and single-strand DNA damage, no clear evidence of more severe genotoxic effects was observed under the tested conditions. Further studies are warranted to elucidate underlying mechanisms and comprehensively assess the safety profile of GQDs for biomedical applications.

Effective removal of various pollutants from the environment has become one of the most important challenges of modern society. Carbon cryogels doped with nitrogen were synthesized and characterized using FTIR. All investigated materials have similar composition and structural disorder. The application of carbon cryogels doped with nitrogen for adsorption from tap water with the addition of OP pesticides gave successful results in stationary and dynamic conditions. Stationary conditions showed successful removal of aliphatic dimethoate and malathion for all tested materials, but they were less effective for aromatic chlorpyrifos. Under dynamic conditions, all materials effectively removed malathion and chlorpyrifos while showing suboptimal performance for dimethoate adsorption. The demonstrated efficiency indicates the potential application of these materials in water treatment. The toxicity of these pesticide solutions decreases over time, indicating that no more toxic products are formed.

The requirements for the efficient replacement of fossil fuel, combined with the growing energy crisis, places focus on hydrogen production. Efficient and cost-effective electrocatalysts are needed for H2 production, and novel strategies for their discovery must be developed. Here, we utilized Kinetic Monte Carlo (KMC) simulations to demonstrate that hydrogen evolution reaction (HER) can be boosted via hydrogen spillover to the support when the catalyst surface is largely covered by adsorbed hydrogen under operating conditions. Based on the insights from KMC, we synthesized a series of reduced graphene-oxide-supported catalysts and compared their activities towards HER in alkaline media with that of corresponding pure metals. For Ag, Au, and Zn, the support effect is negative, but for Pt, Pd, Fe, Co, and Ni, the presence of the support enhances HER activity. The HER volcano, constructed using calculated hydrogen binding energies and measured HER activities, shows a positive shift of the strong binding branch. This work demonstrates the possibilities of metal–support interface engineering for producing effective HER catalysts and provides general guidelines for choosing novel catalyst–support combinations for electrocatalytic hydrogen production.

The conductivity and the state of the surface of supports are of vital importance for metallization via electrodeposition. In this study, we show that the metallization of a carbon fiber-reinforced polymer (CFRP) can be carried out directly if the intermediate graphene oxide (GO) layer is chemically reduced on the CFRP surface. Notably, this approach utilizing only the chemically reduced GO as a conductive support allows us to obtain insights into the interaction of rGO and the electrodeposited metal. Our study reveals that under the same contact current experimental conditions, the electrodeposition of Cu and Ni on rGO follows significantly different deposition modes, resulting in the formation of three-dimensional (3D) and free-standing metallic foils, respectively. Considering that Ni adsorption energy is larger than Ni cohesive energy, it is expected that the adhesion of Ni on rGO@CFRP is enhanced compared to Cu. In contrast, the adhesion of deposited Ni is reduced, suggesting diffusion of H+ between rGO and CFRP, which promotes the hydrogen evolution reaction (HER) and results in the formation of free-standing Ni foils. We ascribe this phenomenon to the unique properties of rGO and the nature of Cu and Ni deposition from electrolytic baths. In the latter, the high adsorption energy of Ni on defective rGO along with HER is the key factor for the formation of the porous layer and free-standing foils.