Binder Free Modification of Glassy Carbon Electrode by Employing Reduced Graphene Oxide/ZnO Composite for Voltammetric Determination of Certain Nitroaromatics

Titanium Carbide (Ti3C2Tx) MXene as Efficient Electron/Hole Transport Material for Perovskite Solar Cells and Electrode Material for Electrochemical Biosensors/Non-Biosensors Applications

Recently, two-dimensional (2D) MXenes materials have received enormous attention because of their excellent physiochemical properties such as high carrier mobility, metallic electrical conductivity, mechanical properties, transparency, and tunable work function. MXenes play a significant role as additives, charge transfer layers, and conductive electrodes for optoelectronic applications. Particularly, titanium carbide (Ti3C2Tx) MXene demonstrates excellent optoelectronic features, tunable work function, good electron affinity, and high conductivity. The Ti3C2Tx has been widely used as electron transport (ETL) or hole transport layers (HTL) in the development of perovskite solar cells (PSCs). Additionally, Ti3C2Tx has excellent electrochemical properties and has been widely explored as sensing material for the development of electrochemical biosensors. In this review article, we have summarized the recent advances in the development of the PSCs using Ti3C2Tx MXene as ETL and HTL. We have also compiled the recent progress in the fabrication of biosensors using Ti3C2Tx-based electrode materials. We believed that the present mini review article would be useful to provide a deep understanding, and comprehensive insight into the research status.

Hydrothermal Synthesis of MnO2/Reduced Graphene Oxide Composite for 4-Nitrophenol Sensing Applications

Recently, the electrochemical sensing approach has attracted materials/electrochemical scientists to design and develop electrode materials for the construction of electrochemical sensors for the detection of para-nitrophenol (4-NP). In the present study, we have prepared a hybrid composite of MnO2 and rGO (MnO2/rGO) using a hydrothermal approach. The morphological features of the prepared MnO2/rGO composite were studied by scanning electron microscopy, whereas the phase purity and formation of the MnO2/rGO composite were authenticated via the powder X-ray diffraction method. Energy-dispersive X-ray spectroscopy was also employed to analyze the elemental composition of the prepared MnO2/rGO composite. In further studies, a glassy carbon electrode (GCE) was modified with MnO2/rGO composite (MnO2/rGO/GCE) and explored as 4-nitrophenol (4-NP) sensor. The fabricated MnO2/rGO/GCE exhibited a reasonably good limit of detection of 0.09 µM with a sensitivity of 0.657 µA/µMcm2. The MnO2/rGO/GCE also demonstrates good selectivity, stability and repeatability in 50 cycles.

Sensing Methods for Hazardous Phenolic Compounds Based on Graphene and Conducting Polymers-Based Materials

It has been known for years that the phenolic compounds are able to exert harmful effects toward living organisms including humans due to their high toxicity. Living organisms were exposed to these phenolic compounds as they were released into the environment as waste products from several fast-growing industries. In this regard, tremendous efforts have been made by researchers to develop sensing methods for the detection of these phenolic compounds. Graphene and conducting polymers-based materials have arisen as a high potential sensing layer to improve the performance of the developed sensors. Henceforth, this paper reviews the existing investigations on graphene and conducting polymer-based materials incorporated with various sensors that aimed to detect hazardous phenolic compounds, i.e., phenol, 2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, pentachlorophenol, 2-nitrophenol, 4-nitrophenol, 2,4-dinitrophenol, and 2,4-dimethylphenol. The whole picture and up-to-date information on the graphene and conducting polymers-based sensors are arranged in systematic chronological order to provide a clearer insight in this research area. The future perspectives of this study are also included, and the development of sensing methods for hazardous phenolic compounds using graphene and conducting polymers-based materials is expected to grow more in the future.

Binder-Free Modification of a Glassy Carbon Electrode by Using Porous Carbon for Voltammetric Determination of Nitro Isomers

In this study, Liquidambar formosana tree leaves have been used as a renewable biomass precursor for preparing porous carbons (PCs). The PCs were produced by pyrolysis of natural waste of leaves after 10% KOH activation under a nitrogen atmosphere and characterized by a variety of state-of-the-art techniques. The PCs possess a large surface area, micro-/mesoporosity, and functional groups on its surface. A glassy carbon electrode modified with high PCs was explored as an efficient binder-free electrocatalyst material for the voltammetric determination of nitro isomers such as 3-nitroaniline (3-NA) and 4-nitroaniline (4-NA). Under optimal experimental conditions, the electrochemical detection of 3-NA and 4-NA was found to have a wide linear range of 0.2-115.6 and 0.5-120 μM and a low detection limit of 0.0551 and 0.0326 μM, respectively, with appreciable selectivity. This route not only enhanced the benefit from biomass wastes but also reduced the cost of producing electrode materials for electrochemical sensors. Additionally, the sensor was successfully applied in the determination of nitro isomers even in the presence of other common electroactive interference and real samples analysis (beverage and pineapple jam solutions). Therefore, the proposed method is simple, rapid, stable, sensitive, specific, reproducible, and cost-effective and can be applicable for real sample detection.