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Oxygen reduction reaction (ORR) is a very important reaction that occurs at the cathodic side in proton exchange membrane fuel cells (PEMFCs). The high cost associated with frequently used Pt-based electrocatalysts for ORR limits the commercialization of PEMFCs. Through bifunctional and electronic effects, theoretical calculations have proved that alloying Pt with a suitable transition metal is likely to improve ORR mass activity when compared to Pt-alone systems. Herein, we demonstrate the preparation of bimetallic Pt–Fe nanoparticles supported on reduced graphene oxide sheets (RGOs) via a simple surfactant-free chemical reduction method. The present method produces PtFe/RGO catalyst particles with a 3.2 nm diameter without agglomeration. PtFe/RGO showed a noticeable positive half-wave potential (0.503 V vs. Ag/AgCl) compared with a commercial Pt/C catalyst (0.352 V vs. Ag/AgCl) with minimal Pt-loading on a glassy carbon electrode. Further, PtFe/RGO showed a higher ORR mass activity of 4.85 mA/cm2-geo compared to the commercial Pt/C (3.60 mA/cm2-geo). This work paves the way for designing noble−transition metal alloy electrocatalysts on RGO supports as high-performance electrocatalysts for ORR application.

Graphene is an intriguing two-dimensional honeycomb-like carbon material with a unique basal plane structure, charge carrier mobility, thermal conductivity, wide electrochemical spectrum, and unusual physicochemical properties. Therefore, it has attracted considerable scientific interest in the field of nanoscience and bionanotechnology. The high specific surface area of graphene allows it to support high biomolecule loading for good detection sensitivity. As such, graphene, graphene oxide (GO), and reduced GO are excellent materials for the fabrication of new nanocomposites and electrochemical sensors. Graphene has been widely used as a chemical building block and/or scaffold with various materials to create highly sensitive and selective electrochemical sensing microdevices. Over the past decade, significant advancements have been made by utilizing graphene and graphene-based nanocomposites to design electrochemical sensors with enhanced analytical performance. This review focus on the synthetic strategies, as well as the structure-to-function studies of graphene, electrochemistry, novel multi nanocomposites combining graphene, limit of detection, stability, sensitivity, assay time. Finally, the review describes the challenges, strategies and outlook on the future development of graphene sensors technology that would be usable for the internet of things are also highlighted.

Herein, we describe a high-performance electrochemical sensor for the detection of regorafenib (REG) using bimetallic Pd–Ru nanoparticles anchored on pomegranate peel extract (PPE) derived reduced graphene oxide (Pd–Ru/rGO). PPE was employed to neutralize the extremely acidic graphene then cast-off along with the metal precursor for the duration of the chemical reduction to accomplish well dispersed Pd–Ru nanoparticles. Bimetallic Pd–Ru/rGO nanocomposites were synthesized using a facile chemical reduction method. Under optimal conditions, based on the differential pulse voltammetric studies it has been confirmed that the fabricated sensors has good electrocatalytic activity toward the detection of REG, spanning over the linear dynamic range of 0.5–300 nM. Moreover, the sensor exhibited a low limit of detection of 1.6 nM and a limit of quantification of 4.8 nM. The electrochemical sensor unveiled admirable selectivity and sensitivity, reproducibility, and repeatability. The fabricated sensor was suitable for real sample analysis (pharmaceutical tablet, human blood plasm, wastewater) with satisfactory recovery. The strategy presented herein can be employed in the development of electrochemical sensors for other target analytes.

TiO2 nanoparticles anchored on the reduced graphene oxide (rGO) nanocomposites were prepared by hydrothermal method and characterized by the X- ray diffraction (XRD) and transmission electron microscopy (TEM). An effective electrochemical sensing platform for the detection of Rifampicin based upon TiO2 nanoparticles anchored graphene oxide sheets modified glassy carbon electrode (TiO2/rGO/GCE) is reported. Moreover, the TiO2/rGO modified glassy carbon electrode showed an excellent selectivity towards the detection of an anti-tuberculosis drug (Rifampicin). The TiO2/rGO/GCE electrochemical sensing platform is found to exhibit linear range from 0.01 – 0.1 nM with a low limit of detection 0.03 μM. The fabricated TiO2/rGO/GCE sensor is explored high sensitivity, high stable and good reproducible towards the sensing of RIF and has the potential to be utilized as a clinical assay and pharmaceuticals.