Developing Low-Cost, High Performance, Robust and Sustainable Perovskite Electrocatalytic Materials in the Electrochemical Sensors and Energy Sectors: “An Overview”

Construction of an electrochemical sensor towards environmental hazardous 4-nitrophenol based on Nd(OH)3-embedded VSe2 nanocomposite

The toxicity of 4-nitrophenol (4-NP) is one of the most common threats to the environment; therefore, developing a simple and sensitive analytical method to detect 4-NP is crucial. In this study, we prepared the Nd(OH)3/VSe2 nanocomposite using the simple hydrothermally assisted ultrasonication method and it was used to detect the 4-NP. Different characterization techniques were used to investigate the morphological and chemical compositions of Nd(OH)3/VSe2 nanocomposite. All of these investigations revealed that Nd(OH)3 nanoparticles were finely dispersed on the surface of the VSe2 nanosheet. The electrical conductivity of our prepared samples was evaluated by the electrochemical impedance spectroscopic technique. The CV and DPV methods were used to explore the electrochemical activity of 4-NP at the Nd(OH)3/VSe2/GCE sensor which exhibited a wide linear range (0.001 to 640 µM), low limit of detection (0.008 µM), and good sensitivity (0.41 µA µM-1 cm-2), respectively. Additionally, Nd(OH)3/VSe2/GCE sensor was tested in water samples for the detection of 4-NP, which exhibited good recovery results. The Nd(OH)3/VSe2 electrode material is a novel one for the electrochemical sensor field, and the obtained overall results also proved that our proposed material is an active material for sensor applications.

Ultrasensitive electrochemical sensor for the detection of carbamazepine based on gadolinium vanadate nanostructure decorated functionalized carbon nanofiber nanocomposite

The gadolinium vanadate nanostructure decorated functionalized carbon nanofiber (GdVO₄/f-CNF) nanocomposite was prepared by the hydrothermal method, which is fabricated on a glassy carbon electrode (GCE) for the determination of carbamazepine (CBZ). The structural morphology of the hydrothermally synthesized GdVO₄/f-CNF material was investigated by several spectroscopy methods such as FESEM, HRTEM, EDS-mapping, XRD, XPS, and Raman. Moreover, the electrical conductivity of our synthesized material was inspected by the electrochemical impedance spectroscopy (EIS) analysis, and the electrochemical performance towards CBZ was inspected by the cyclic voltammetry (CV) and amperometry (AMP) analysis under optimized conditions. The AMP determination of CBZ exhibits the lowest level LOD of 0.0018 μM and a good linear range of 0.01-157 μM. Additionally, our proposed sensor was used to determine the CBZ in the pharmaceutical and, human urine samples which have exposed the acceptable recoveries.

Graphene-Based Sensor for the Detection of Cortisol for Stress Level Monitoring and Diagnostics

In this work, we study the sensing properties of multi-layer graphene combined with pyrrole in order to elaborate low-cost, high-sensitive material for cortisol detection. Graphene nanoplatelets and pyrrole were dispersed in a solution containing 1M HNO3 by using a powerful ultrasound probe for 10 min, then centrifuged for 30 min at 4000 rpm; polymerization was performed by cyclic voltammetry. The graphene-pyrrole composite was tested to ultra-low levels of cortisol in artificial saliva, consistent to the levels excreted in human salivary samples. The composite was further investigated by Raman spectroscopy and we modeled the interaction between the sensitive layer and cortisol using MarvinBeans software. It shows a good sensitivity for salivary values of cortisol cyclic voltammetry being able to detect a level down to 0.5 ng/mL cortisol.

A novel electrochemical sensor for the detection of enrofloxacin based on a 3D flower-like metal tungstate-incorporated reduced graphene oxide nanocomposite

In recent times, metal tungstates have received a lot of attention in various research fields. Accordingly, the CaWO₄/RGO (CW/RGO) nanocomposite was prepared by a facile hydrothermal method. The electrocatalytic performance of the hydrothermally prepared CW/RGO nanocomposite was used for the electrochemical detection of the antibiotic medicine enrofloxacin (ENF). The electrocatalytic oxidation performance of ENF was examined by cyclic voltammetry (CV) and amperometry (AMP) techniques. The CV results showed the lowest anodic peak potential and the enhanced anodic peak current response compared to the other modified electrodes. Mainly, our newly proposed sensor exhibited excellent electrochemical performance with the lowest limit of detection (LOD) of 0.021 μM, and a significant linear range of 0.001-115 μM. Additionally, our proposed sensor exhibited good selectivity, great long-term stability, and excellent reproducibility. Then, our proposed sensor was successfully applied to detect the amount of ENF in a milk sample and river water, which exhibited good satisfactory results.

Sensitive Electrochemical Detection of Bioactive Molecules (Hydrogen Peroxide, Glucose, Dopamine) with Perovskites-Based Sensors

Perovskite-modified electrodes have received increasing attention in the last decade, due to their electrocatalytic properties to undergo the sensitive and selective detection of bioactive molecules, such as hydrogen peroxide, glucose, and dopamine. In this review paper, different types of perovskites involved for their electrocatalytic properties are described, and the proposed mechanism of detection is presented. The analytical performances obtained for different electroactive molecules are listed and compared with those in terms of the type of perovskite used, its nanostructuration, and its association with other conductive nanomaterials. The analytical performance obtained with perovskites is shown to be better than those of Ni and Co oxide-based electrochemical sensors. Main trends and future challenges for enlarging and improving the use of perovskite-based electrochemical sensors are then discussed.

Nanostructured perovskite type gadolinium orthoferrite decorated RGO nanocomposite for the detection of nitrofurantoin in human urine and river water samples

Nitrofurantoin (NFT) is mainly used in humans for the treatment of urinary tract infections. NFT is used as feed additives in animals, due to its broad antimicrobial activity. However, it shows more side effects on human health and the environment. Therefore low-cost, portable, and rapid sensors are necessary for the detection of NFT in real samples. Herein, we successfully developed an electrochemical sensor using a glassy carbon electrode (GCE) modified with gadolinium orthoferrite (GdFeO₃) decorated on reduced graphene oxide (RGO) nanocomposite for the detection of NFT. The facile hydrothermal method was used to synthesis a novel GdFeO₃/RGO nanocomposite, the morphological and structural characterization was confirmed by the FESEM, HRTEM, EDX, XRD, Raman, and XPS techniques. The formation mechanism of GdFeO₃/RGO nanocomposite had been discussed. The effective intercalation of the nanostructured GdFeO₃ to the RGO sheets leads to the significant enhancement in physicochemical properties such as electrical conductivity, electro-active surface area, structural stability, and electrochemical activity, which was observed from the EIS and CV experimental results. The electrochemical studies established that the developed GdFeO₃/RGO sensor was highly sensitive and selective to NFT. Moreover, the GdFeO₃/RGO sensor exhibits good sensitivity of 4.1985 μA μM^-1 cm^-2, a low detection limit (LOD) of 0.0153 µM and a linear range from 0.001 to 249 µM for NFT detection under optimized experimental conditions. In addition, the investigation of storage time on the CV response of the GdFeO₃/RGO sensor indicates superior stability. Owing to these extraordinary analytical advantages, the as-fabricated sensor was applied to detect the NFT levels in human urine and river water samples with satisfactory results.

Cellulose Nanofiber Composite with Bimetallic Zeolite Imidazole Framework for Electrochemical Supercapacitors

Cellulose nanofiber (CNF) and hybrid zeolite imidazole framework (HZ) are an emerging biomaterial and a porous carbonous material, respectively. The composite of these two materials could have versatile physiochemical characteristics. A cellulose nanofiber and cobalt-containing zeolite framework-based composite was prepared using an in-situ and eco-friendly chemical method followed by pyrolysis. The composite was comprised of cobalt nanoparticles decorated on highly graphitized N-doped nanoporous carbons (NPC) wrapped with carbon nanotubes (CNTs) produced from the direct carbonization of HZ. By varying the ratio of CNF in the composite, we determined the optimal concentration and characterized the derived samples using sophisticated techniques. Scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS) confirmed the functionalization of CNF in the metallic cobalt-covered N-doped NPC wrapped with CNTs. The CNF–HZNPC composite electrodes show superior electrochemical performance, which is suitable for supercapacitor applications; its specific capacitance is 146 F/g at 1 A/g. Furthermore, the composite electrodes retain a cycling stability of about 90% over 2000 charge–discharge cycles at 10 A/g. The superior electrochemical properties of the cellulose make it a promising candidate for developing electrodes for energy storage applications.