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By utilizing the combustion process, nanoparticles can be produced quickly, easily, and in an environmentally friendly manner. In this study, sheep dung is employed as fuel for the synthesis of nickel oxide nanoparticles (NiO-SD), and characterization techniques such as XRD, FTIR, UV, FESEM, and EDX, are used to confirm the as-desired nanoparticles. Malachite green (MG) and methylene blue (MB), respectively, are used as benchmark dyes to measure the photocatalytic effectiveness of the material and systematically investigated the effects of the light source, dye concentration, dose of photocatalyst, and pH value on the effectiveness of photocatalyst and photodegradation kinetics. It is found that the NiO-SD, when exposed to UV light, shows good removal effectiveness of the MB and MG dyes, according to the photodegradation data of 99.9% and 96.8%, respectively. The remarkable photodegradation efficiency of MB and MG dyes over the developed photocatalyst is also explained by a plausible photo-catalytic process. The green-manufactured photocatalyst can be a promising for ecological applications such as waste-water remediation.

In this paper we present the characterization of 3D-printed nanocarbon electrodes (3DnCes) and their application in electrochemical enzyme-linked detection of DNA hybridization. The approach takes advantage of a facile procedure based on adsorption of target DNA on the electrode surface followed by hybridization with a biotinylated probe and binding of streptavidin–alkaline phosphatase conjugate. The alkaline phosphatase converts 1-naphthyl phosphate in the background electrolyte into electrochemically oxidizable 1-naphthol, which is subsequently detected using linear sweep voltammetry. The preparation, characterization, and analytical performance of the 3DnCes are reported. The results show the applicability of such 3DnCes in detection of target DNA hybridization specifically with the complementary biotinylated probe, and indicate the potential of 3D printed electrodes for use in various bioanalytical approaches.

Globally, researchers have devoted consistent efforts to producing excellent coating properties since coating plays an essential role in enhancing electrochemical performance and surface quality. In this study, TiO2 nanoparticles in varying concentrations of 0.5, 1, 2, and 3 wt.% were added into the acrylic-epoxy polymeric matrix with 90:10 wt.% (90A:10E) ratio incorporated with 1 wt.% graphene, to fabricate graphene/TiO2 -based nanocomposite coating systems. Furthermore, the properties of the graphene/TiO2 composites were investigated by Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), ultraviolet-visible (UV-Vis) spectroscopy, water contact angle (WCA) measurements, and cross-hatch test (CHT), respectively. Moreover, the field emission scanning electron microscope (FESEM) and the electrochemical impedance spectroscopy (EIS) tests were conducted to investigate the dispersibility and anticorrosion mechanism of the coatings. The EIS was observed by determining the breakpoint frequencies over a period of 90 days. The results revealed that the TiO2 nanoparticles were successfully decorated on the graphene surface by chemical bonds, which resulted in the graphene/TiO2 nanocomposite coatings exhibiting better dispersibility within the polymeric matrix. The WCA of the graphene/TiO2 coating increased along with the ratio of TiO2 to graphene, achieving the highest CA of 120.85° for 3 wt.% of TiO2. Excellent dispersion and uniform distribution of the TiO2 nanoparticles within the polymer matrix were shown up to 2 wt.% of TiO2 inclusion. Among the coating systems, throughout the immersion time, the graphene/TiO2 (1:1) coating system exhibited the best dispersibility and high impedance modulus values (Z0.01 Hz), exceeding 1010 Ω cm2.

Abstract Mesoporous α-iron oxide@graphitized-carbon nitride nanocomposites (α-Fe2O3@g-C3N4-NCs) were synthesized using urea-formaldehyde (UF) resins at 400 °C/2 h. The mesoporous nature of the prepared nanocomposites was observed from electron microscopy and surface area measurements. The electrochemical measurements show the bifunctional nature of mesoporous α-Fe2O3@g-C3N4-NCs in electrolysis of water for oxygen evolution and oxygen reduction reactions (OER/ORR) using 0.5 M KOH. Higher current density of mesoporous α-Fe2O3@g-C3N4-NCs reveals the enhanced electrochemical performance compared to pure Fe2O3 nanoparticles (NPs). The onset potential, over-potential and Tafel slopes of mesoporous α-Fe2O3@g-C3N4-NCs were found lower than that of pure α-Fe2O3-NPs. Rotating disc electrode experiments followed by the K-L equation were used to investigate 4e− redox system. Therefore, the mesoporous α-Fe2O3@g-C3N4-NCs bifunctional electro-catalysts can be considered as potential future low-cost alternatives for Pt/C catalysts, which are currently used in fuel cells.

The hydrogen evolution reaction (HER) is important for the advancement of next-generation electrochemical energy devices. The search for an alternative inexpensive catalyst for energy conversion to replace expensive and rare noble metals is of high priority. There has been a significant push to investigate electrocatalysis of various layered materials for hydrogen evolution. However, the electrocatalytic activity of layered MAX phases remains largely unexplored. Herein, electrocatalytic activity studies of MAX (Ti2AlC, Ta2AlC, Ti2SnC, Ti3SiC2, V2AlC, Mo2TiAlC2, and Cr2AlC) phases are conducted. Material and electrochemical characterization are carried out to understand the morphology and catalytic activity, respectively. From Tafel slope analysis, it was found that proton adsorption is the rate-limiting step for all the MAX phases studied. Double transition-metal MAX carbides (Mo2TiAlC2) showed better catalytic activity for HER than single transition-metal MAX carbides.

3D printing is a manufacturing technique used to prototype devices with customized shapes composed of different materials, including carbon composites. Toxic phenolic compounds are a major environmental hazard. Herein, we demonstrate the use of carbon-based 3D-printed electrodes for the detection of chlorophenols and nitrophenols. The influence of pH on the voltammetric response was studied, and an alkaline pH was identified as the best environment for the detection of substituted phenols. Simultaneous detection of phenolic compounds was performed using differential pulse voltammetry. This approach appears promising for the fabrication of electrochemical sensors.

3D-printing technology is widely accepted as a scalable and advanced manufacturing procedure for the fabrication of electrodes for electrochemical applications. 3D-printed carbon-based electrodes can be used for electrochemical analysis, replacing conventional carbon electrodes. However, a bare 3D-printed carbon electrode exhibits poor electrochemical performance. Herein, a post-treatment of 3D-printed electrodes was carried out using catalytically active materials to improve their electrochemical performance. We used a dip-coating technique which is a more universal, facile, and cost-effective approach compared with other conventionally used techniques such as atomic layer deposition or electrodeposition. The 3D-printed nanocarbon electrodes were dip-coated with MXene (Ti3C2Tx) and different transition metal dichalcogenides such as MoS2, MoSe2, WS2, and WSe2 to study their catalytic activity towards the hydrogen evolution reaction (HER). This study demonstrates a simple method of improving the catalytic surface properties of 3D-printed nanocarbon electrodes for energy conversion applications.

The decentralized fabrication of sensors using 3D-printing technology and low power requirements of electrochemical detection promise to revolutionize point-of-care sensing. One of the obstacles is that the 3D-printed devices are often not catalytic to the target analytes. Here, we develop a non-enzymatic printed nanocarbon electrode sensor to detect sugars (glucose and sucrose) via copper and nickel electroplating over a 3D-printed conducting electrode. The morphological and spectroscopic characterizations of copper-plated and nickel-plated 3D-printed carbon electrodes were performed. Scanning electron micrographs show the formation of metal nanoparticles over the surface of a 3D-printed nanocarbon electrode. X-ray photoelectron spectroscopy reveals the composition and chemical states of the metal coating. Electrochemical characterization via cyclic voltammetry and chronoamperometry was carried out, and glucose and sucrose sensing were performed. This method of on-demand decentralized sensor fabrication and modifications should find broad applications.

Additive manufacturing, also termed 3D printing, enables economical, dynamic and rapid fabrication of customisable three-dimensional (3D) devices catering for specialised functions. Herein, we report the fabrication of 3D-printed graphene electrodes by fused deposition modelling (FDM), which were then used for the electrochemical detection of the mycotoxin zearalenone (ZEA). Chemical and electrochemical pre-treatment procedures were applied to remove the inert polylactic acid external layer from the graphene electrodes, exposing and activating the inner graphene surface. These procedures enhanced the sensitivity of the electrodes towards electrochemical detection of ZEA. The activated 3D-printed graphene electrodes displayed a good linear response (r = 0.995) over a wide concentration range (10 to 300 µM). This proof-of-concept application opens up a wide range of possibilities for the fabrication of 3D-printed electrochemical devices for use in food analysis and food safety.

An efficient metal-free domino reaction leading to structural/electronically divergent 1,2-dihydropyridines from easily accessible propargyl vinyl anilines via N-phenyl 3-aza-Cope sigmatropic rearrangement is reported with good to excellent yields using 1,2-dichlorobenzene as solvent under thermal conditions. Spirocyclic substitution is also tolerated under the present optimized conditions.

A series of 3-aryl indazoles and 1-methyl-3-aryl indazole derivatives are prepared with exceptional yields by coupling with several arylboronic acids and methylation by two dissimilar approaches. The as-prepared indazole derivatives (3a–3j) and their N-methyl derivatives (5a–5j) are evaluated for in vitro anticancer activity against two cancer cell lines, HCT-116 and MDA-MB-231. The results reveal that the indazole derivatives tested display mild to moderate anticancer activities against the cell lines tested.

A facile, one-pot, and proficient method was developed for the production of various 2-arylaminobenzimidazoles. This methodology is based for the first time on a copper catalyst promoted domino C–N cross-coupling reaction for the generation of 2-arylaminobenzimidazoles. Mechanistic investigations revealed that the synthetic pathway involves a copper-based desulphurization/nucleophilic substitution and a subsequent domino intra and intermolecular C–N cross-coupling reactions. Some of the issues typically encountered during the synthesis of 2-arylaminobezimidazoles, including the use of expensive catalytic systems and the low reactivity of bromo precursors, were addressed using this newly developed copper-catalyzed method. The reaction procedure is simple, generally with excellent substrate tolerance, and provides good to high yields of the desired products.