Elimination of toxic organic compounds from wastewater is currently one of the most important subjects in water pollution control. Eosin Yellow, an anionic xanthene fluorescent dye, known to be carcinogenic, originates mainly from textile industrial processes and is resistant to conventional chemical or biological water treatment methods. Photocatalysis using non metal/platinum group metal-codoped TiO2 may provide effective means of removing such dyes from contaminated water. In this study, nitrogen/palladium-codoped TiO2 photocatalysts were prepared by calcination of the hydrolysis product of titanium isopropoxide, Ti(OC3H7)4, with aqueous ammonia. Samples were characterized by Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, thermogravimetric analysis (TGA), diffuse reflectance UV–vis spectrophotometry, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Anatase phase particles of size range 10–20 nm were confirmed by XRD, Raman, TEM, and SEM analysis. Codoping imparted a red shift in the absorption edges of the materials. Codoped TiO2 showed greater photocatalytic Eosin Yellow degradation efficiency compared to singly doped N–TiO2 or Pd–TiO2 under visible light irradiation. The highest initial reaction rate of 2.238 × 10–2 min–1 was observed for N/Pd–TiO2 (0.8% Pd). The results demonstrated that the N/Pd-codoped TiO2 (0.6% Pd) sample could completely degrade the dye in 3 h, while the commercial TiO2, (Degussa P25) showed the lowest dye degradation efficiency.

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Perovskites are known for their high yield photoluminescence and higher photovoltaic conversion efficiencies. To make them practically useful, the toxicity and stability issues need to be addressed. Herein, we report a less toxic and stable silver bismuth iodide quantum dot system, prepared by a modified ligand assisted reprecipitation (LARP) method. Three types of phase structures such as AgBiI 4 , Ag 2 BiI 5 , and AgBi 2 I 7 were obtained, and their structural and photophysical properties were investigated. By replacing lead (Pb), the toxicity would be reduced considerably and the optical properties persisted for more than six months at ambient conditions. The as-prepared silver bismuth iodide QDs were then used to construct photodetector devices, and the device performances were studied. The constructed photodetector devices have generated the photocurrent values of (AgBi 2 I 7 ∼ 0.12 and 0.32 mA), (Ag 2 BiI 5 ∼ 0.87 and 1.6 μA), and (AgBiI 4 ∼ 0.16 and 0.61 mA) at different biasing voltages of 0.1 and 0.2 V, respectively, under visible light irradiation. The AgBi 2 I 7 QD system generated higher photocurrent value and exhibited a better ON/OFF ratio of (I on /I off = 6.5 × 10 4 ). The silver bismuth iodide QDs based photodetectors are promising for ultraviolet photodetection.

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Graphitic carbon nitride (g-C3N4) is a two-dimensional conjugated polymer that has attracted the interest of researchers and industrial communities owing to its outstanding analytical merits such as low-cost synthesis, high stability, unique electronic properties, catalytic ability, high quantum yield, nontoxicity, metal-free, low bandgap energy, and electron-rich properties. Notably, graphitic carbon nitride (g-C3N4) is the most stable allotrope of carbon nitrides. It has been explored in various analytical fields due to its excellent biocompatibility properties, including ease of surface functionalization and hydrogen-bonding. Graphitic carbon nitride (g-C3N4) acts as a nanomediator and serves as an immobilization layer to detect various biomolecules. Numerous reports have been presented in the literature on applying graphitic carbon nitride (g-C3N4) for the construction of electrochemical sensors and biosensors. Different electrochemical techniques such as cyclic voltammetry, electrochemiluminescence, electrochemical impedance spectroscopy, square wave anodic stripping voltammetry, and amperometry techniques have been extensively used for the detection of biologic molecules and heavy metals, with high sensitivity and good selectivity. For this reason, the leading drive of this review is to stress the importance of employing graphitic carbon nitride (g-C3N4) for the fabrication of electrochemical sensors and biosensors.