Genghuang Wu

Advances in enzyme-free electrochemical sensors for hydrogen peroxide, glucose, and uric acid

AbstractEnzyme-free (also called non-enzymatic or direct) electrochemical sensors have been widely used for the determination of hydrogen peroxide, glucose, and uric acid. This review covers the recent progress made in this field. We also discuss the respective sensor materials which have strong effect on the electro-catalytic properties of the electrodes and govern the performance of these sensors. In addition, perspectives and current challenges of enzyme-free electrochemical sensors are outlined. Contains 142 references. FigureIn the recent past, publications related to enzyme-free electrochemical sensors became plentiful. In this paper, we give an overview on the recent developments of enzyme-free sensors including hydrogen peroxide, glucose and uric acid sensors.

Graphene and graphene-based nanomaterials: the promising materials for bright future of electroanalytical chemistry

Similar to its popular older cousins of fullerene and carbon nanotubes (CNTs), the latest form of nanocarbon, graphene, is inspiring intensive research efforts in its own right. As an atomically thin layer of sp(2)-hybridized carbon, graphene possesses spectacular electronic, optical, magnetic, thermal and mechanical properties, which make it an exciting material in a variety of important applications. In this review, we present the current advances in the field of graphene electroanalytical chemistry, including the modern methods of graphene production, and graphene functionalization. Electrochemical (bio) sensing developments using graphene and graphene-based materials are summarized in more detail, and we also speculate on their future and discuss potential progress for their applications in electroanalytical chemistry.

Non-enzymatic electrochemical glucose sensor based on platinum nanoflowers supported on graphene oxide

A non-enzymatic electrochemical method was developed for glucose detection using a glassy carbon electrode modified with platinum nanoflowers supported on graphene oxide (PtNFs-GO). PtNFs-GO was synthesized using a nontoxic, rapid, one-pot and template-free method. Low-cost, green solvent ethanol acted as the reductant, and the advanced and effective 2D carbon material-GO nanosheet acted as the stabilizing material. Their morphologies were characterized using transmission electron microscopy. Cyclic voltammetry and amperometric methods were used to evaluate the electrocatalytic activity towards glucose in neutral media. The modified electrode exhibited strong and sensitive amperometric responses to glucose even in the presence of a high concentration of chloride ions. The response time was within 5s. The interference effects from ascorbic acid and uric acid were comparatively small when operated at suitable potential. Under optimal detection potential (0.47 V with a saturated calomel reference electrode) the PtNFs-GO modified electrode performed a current response towards glucose at a broad concentration range from 2 μM to 20.3mM. Two linear regions could be observed at 2 μM to 10.3mM with a sensitivity of 1.26 μA mM(-1)cm(-2) (correlation coefficient 0.9968), and at 10.3mM to 20.3mM with a sensitivity of 0.64 μA mM(-1)cm(-2)(correlation coefficient 0.9969). The LOD of 2 μM was lower than many non-enzymatic electrochemical glucose sensors. The modified electrode was also applied to the determination of glucose in glucose injection solutions, and the satisfactory results obtained indicated that it was promising for the development of a novel non-enzymatic electrochemical glucose sensor.

An electrochemical ascorbic acid sensor based on palladium nanoparticles supported on graphene oxide

In this study, an electrochemical ascorbic acid (AA) sensor was constructed based on a glassy carbon electrode modified with palladium nanoparticles supported on graphene oxide (PdNPs-GO). PdNPs with a mean diameter of 2.6 nm were homogeneously deposited on GO sheets by the redox reaction between PdCl(4)(2-) and GO. Cyclic voltammetry and amperometric methods were used to evaluate the electrocatalytic activity towards the oxidation of AA in neutral media. Compared to a bare GC or a Pd electrode, the anodic peak potential of AA (0.006 V) at PdNPs-GO modified electrode was shifted negatively, and the large anodic peak potential separation (0.172 V) of AA and dopamine (DA), which could contribute to the synergistic effect of GO and PdNPs, was investigated. A further amperometric experiment proved that the proposed sensor was capable of sensitive and selective sensing of AA even in the presence of DA and uric acid. The modified electrode exhibited a rapid response to AA within 5s and the amperometric signal showed a good linear correlation to AA concentration in a broad range from 20 μM to 2.28 mM with a correlation coefficient of R=0.9991. Moreover, the proposed sensor was applied to the determination of AA in vitamin C tablet samples. The satisfactory results obtained indicated that the proposed sensor was promising for the development of novel electrochemical sensing for AA determination.

Platinum nanoflowers supported on graphene oxide nanosheets: their green synthesis, growth mechanism, and advanced electrocatalytic properties for methanol oxidation

This paper reports a nontoxic, rapid, one-pot and template-free synthesis of three-dimensional (3D) Pt nanoflowers (PtNFs) with high yield and good size monodispersity supported on graphene oxide (GO) nanosheets. The key synthesis strategy employed a low-cost, green solvent, ethanol as the reductant and an advanced, powerful 2D carbon material, GO nanosheets as the stabilizing material. The resulting PtNFs-GO nanosheets were characterized by transmission electron microscopy (TEM), high-resolution TEM, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and electrochemical techniques. It was found that the monodispersed, porous PtNFs supported on GO nanosheets were a uniform size of 30 nm and each was composed of numerous “clean” and small (4 nm) Pt nanoparticles, which revealed an unusually high activity for methanol oxidation reaction compared to commercial Pt black. Furthermore, based on a systematic study of the PtNFs growth conditions, a possible mechanism, and especially the importance of GO in the formation was proposed. Our study demonstrates that GO is a promising support material for developing next-generation advanced Pt based fuel cells and their relevant electrodes in the field of energy.

Dual-functional Pt-on-Pd supported on reduced graphene oxide hybrids: Peroxidase-mimic activity and an enhanced electrocatalytic oxidation characteristic

In this study, a facile hydrothermal method was developed to synthesize Pt-on-Pd supported on reduced graphene oxide (Pt-on-Pd/RGO) hybrids. Because of the synergistic effect between Pt-on-Pd and RGO, the obtained Pt-on-Pd/RGO had superior peroxidase-mimic activities in H2O2 reduction and TMB oxidation. The reaction medium was optimized and a sensing approach for H2O2 was developed with a linear range from 0.98 to 130.7 μM of H2O2. In addition, the characteristic of electrocatalytic oxidation of methanol was investigated. The peak current density value, j(f), for the Pt-on-Pd/RGO hybrid (328 mA mg(Pt)(-1)) was about 1.85 fold higher than that of commercial Pt black (177 mA mg(Pt)(-1)) and, also, more durable electrocatalytic activity could be obtained. For the first time, the dual-functional Pt-on-Pd/RGO with peroxidase-mimic activity and an enhanced electrocatalytic oxidation characteristic was reported.