Various applications of electrochemical sensors and biosensors have been reported in many fields. These include pharmaceuticals, drug detection, cancer detection, and analysis of toxic elements in tap water. Electrochemical sensors are characterised by their low cost, ease of manufacture, rapid analysis, small size and ability to detect multiple elements simultaneously. They also allow the reaction mechanisms of analytes, such as drugs, to be taken into account, giving a first indication of their fate in the body or their pharmaceutical preparation. Several materials are used in the construction of sensors, such as graphene, fullerene, carbon nanotubes, carbon graphite, glassy carbon, carbon clay, graphene oxide, reduced graphene oxide, and metals. This review covers the most recent progress in electrochemical sensors used to analyze drugs and metabolites in pharmaceutical and biological samples. We have highlighted carbon paste electrodes (CPE), glassy carbon electrodes (GCE), screen-printed carbon electrodes (SPCE) and reduced graphene oxide electrodes (rGOE). The sensitivity and analysis speed of electrochemical sensors can be improved by modifying them with conductive materials. Different materials used for modification have been reported and demonstrated, such as molecularly imprinted polymers, multiwalled carbon nanotubes, fullerene (C60), iron(III) nanoparticles (Fe3O4NP), and CuO micro-fragments (CuO MF). Manufacturing strategies and the detection limit of each sensor have been reported.

Recent advances in energy conversion technologies, especially solar-driven photocatalytic water splitting, are vital for satisfying the increasing global need for sustainable and clean energy. Perovskite oxides have attracted considerable attention among photocatalytic materials due to their tunable electronic structures, exceptional stability, and promise for effective hydrogen generation and environmental remediation. In this study, the optoelectronic and photocatalytic (PC) characteristics of ATiO₃ (A = Ca, Mg) perovskites, undoped and codoped with Se and Zr, have been analyzed using ab initio simulations based on the density functional theory (DFT). The calculated formation energies for codoped systems range from −1.01 to −3.32 Ry/atom, confirming their thermodynamic stability. Furthermore, band structure calculations indicate that the undoped compounds CaTiO₃ and MgTiO₃ possess indirect band gaps of 2.766 eV and 2.926 eV, respectively. In contrast, codoping alters the electronic properties by changing the band gap from indirect to direct and reducing its energy, resulting in the direct band gap values 2.153 eV, 1.374 eV, 2.159 eV, and 1.726 eV for the compounds ${{\mathrm{C}\mathrm{a}}_8\mathrm{T}\mathrm{i}}_7{\mathrm{Z}\mathrm{r}}_1{\mathrm{O}}_{23}{\mathrm{S}\mathrm{e}}_1$, ${{\mathrm{C}\mathrm{a}}_8\mathrm{T}\mathrm{i}}_6{\mathrm{Z}\mathrm{r}}_2{\mathrm{O}}_{22}{\mathrm{S}\mathrm{e}}_2$, ${{\mathrm{M}\mathrm{g}}_8\mathrm{T}\mathrm{i}}_7{\mathrm{Z}\mathrm{r}}_1{\mathrm{O}}_{23}{\mathrm{S}\mathrm{e}}_1$, and ${{\mathrm{M}\mathrm{g}}_8\mathrm{T}\mathrm{i}}_6{\mathrm{Z}\mathrm{r}}_2{\mathrm{O}}_{22}{\mathrm{S}\mathrm{e}}_2$, respectively. Additionally, this codoping improves light absorption and optical conductivity in the visible and ultraviolet ranges. These enhancements become increasingly evident with elevated dopant concentrations, leading to intensified light–matter interactions. Analysis of the band edge potentials reveals that the Se-/Zr-codoped CaTiO₃ compounds satisfy the necessary criteria for the photodissociation of water, conferring on them an ability to generate H₂ and O₂ under light irradiation. However, under different pH conditions, Se-/Zr-codoped MgTiO₃ is expected to perform better at higher pH levels, while Se-/Zr-codoped CaTiO₃ is more effective at lower pH levels. These findings highlight the promise of codoped materials for renewable energy applications, such as solar-driven hydrogen production and optoelectronic devices, with pH being a critical factor in enhancing their photocatalytic performance.

Thin films of epoxy/silicone loaded with N-CNT were prepared by a method of sol-gel and deposited on ITO glass substrates at room temperature. The properties of the loaded monolayer samples (0.00, 0.07, 0.1, and 0.2 wt% N-CNTs) were analyzed by UV-visible spectroscopy. The transmittance for the unloaded thin films is 88%, and an average transmittance for the loaded thin film is about 42 to 67% in the visible range. The optical properties were studied from UV-visible spectroscopy to examine the transmission spectrum, optical gap, Tauc verified optical gap, and Urbach energy, based on the envelope method proposed by Swanepoel (1983). The results indicate that the adjusted optical gap of the film has a direct optical transition with an optical gap of 3.61 eV for unloaded thin films and 3.55 to 3.19 eV for loaded thin films depending on the loading rate. The optical gap is appropriately adapted to the direct transition model proposed by Tauc et al. (1966); its value was 3.6 eV for unloaded thin films and from 3.38 to 3.1 eV for loaded thin films; then, we determined the Urbach energy which is inversely variable with the optical gap, where Urbach’s energy is 0.19 eV for the unloaded thin films and varies from 0.43 to 1.33 eV for the loaded thin films with increasing rate of N-CNTs. Finally, nanocomposite epoxy/silicone N-CNT films can be developed as electrically conductive materials with specific optical characteristics, giving the possibility to be used in electrooptical applications.