Pd Electrodes Research Articles

Oxidation of Alloy 690 in Simulated Pressurized Water Reactor Primary Coolant – Experiments and Modeling

During normal operation of the primary loop of a water cooled-water moderated energy reactor (WWER), the associated water chemistry evolves from an initially high-boron high-potassium (beginning-of-cycle, 1200 ppm B and 8 ppm K) to significantly lower concentrations (ca. 400 ppm B and 3.5 ppm K) at the end of the respective campaign. In addition to that, the concentration of Li produced by transmutation of B reaches ca. 0.7 – 0.9 ppm. To the best of our knowledge, the effect of such water chemistry changes on pressurized water reactor (PWR) internals such as Alloy 690 have not been studied yet. Such a study appears relevant also within the frames of a discussion for a possible transition from B-Li to B-K water chemistry in PWRs.In the present paper, the effect of evolution of primary water chemistry during operation on the corrosion rate and conduction mechanism of oxide films on Alloy 690 is studied by in-situ impedance spectroscopy at 280 °C / 8 MPa during 1-week exposures in an autoclave connected to a re-circulation loop. Impedance measurements were performed in three-electrode mode featuring a Pt sheet counter electrode and a Pd electrode negatively polarized with a current of -10 µA vs. another Pt to approximate the reversible hydrogen electrode (RHE). Spectra were recorded at the corrosion potential in a frequency range 10 kHz – 0.1 mHz using an ac amplitude of 50 mV (rms). At the end of exposure, the samples were polarized in the range of potentials -0.1 to 0.5 V vs. RHE to evaluate the stability of the passive oxide. Separate samples of Alloy 690 were simultaneously exposed in the autoclave and subsequently analyzed by Glow-Discharge Optical Emission Spectroscopy (GDOES) in order to estimate the thickness and the in-depth composition of the formed oxides.Impedance data were quantitatively interpreted using the Mixed-Conduction Model for Oxide Films (MCM) to estimate the rates of metal oxidation at the alloy/oxide interface, oxide dissolution and restructuring at the film/coolant interface and ion transport in the protective layer. The effect of water chemistry evolution on corrosion rate and conduction mechanism in the oxide on Alloy 690 in primary coolant is discussed on the basis of the obtained parameters.Acknowledgments: This study is funded by the European Union-NextGenerationEU, through the National Recovery and Resilience Plan of the Republic of Bulgaria, project № BG-RRP-2.004-0002 (BiOrgaMCT).

Enhanced Hydrosaturation Selectivity and Electron Transfer for Electrocatalytic Chlorophenols Hydrogenation on Ru Sites.

Electrocatalytic hydrogenation is acknowledged as a promising strategy for chlorophenol dechlorination. However, the widely used Pd catalysts exhibit drawbacks, such as high costs and low selectivity for phenol hydrosaturation. Herein, we demonstrate the potential and mechanism of Ru in serving as a Pd substitute using 2,4,6-trichlorophenol (TCP) as a model pollutant. Up to 99.8% TCP removal efficiency and 99% selectivity to cyclohexanol, a value-added compound with an extremely low toxicity, were achieved on the Ru electrode. In contrast, only 66% of TCP was removed on the Pd electrode, with almost no hydrosaturation selectivity. The superiority of Ru over Pd was especially noteworthy in alkaline conditions or the presence of interfering species such as S2-. The theoretical simulation demonstrates that Ru possesses a hydrodechlorination energy barrier of 0.72 eV, which is comparable to that on Pd. Meanwhile, hydrosaturation requires an activation energy of 0.69 eV on Ru, which is much lower than that on Pd (0.92 eV). The main reaction mechanism on Ru is direct electron transfer, which is distinct from that on Pd (indirect pathway via atomic hydrogen, H*). This work thereby provides new insights into designing cost-effective electrocatalysts for halogenated phenol detoxification and resource recovery.

Low-temperature co-fired PZNN-PZT multilayer piezoelectric ceramics with excellent electrical and bending properties

A 0.65 Pb(Zr0.47Ti0.53)O3–0.35[Pb(Zn0.1Ni0.9)1/3Nb2/3]O3 (PZNN-PZT) piezoceramic with sintering aids of Li2CO3, Bi2O3, CuO and Sm2O3 was prepared via a traditional solid reaction to achieve a high-performance multilayer actuator. The microstructure and electrical properties of ceramic bulks were systematically explored. The piezoceramics sintered at various temperatures show multi-phase co-existence. The sintering aids are beneficial for grain growth and microstructure densification. The piezoceramic sintered at 960 °C possesses relatively desirable electrical properties, including d33 ∼ 550 pC/N, kp ∼0.7 εr ∼2200, tan δ ∼0.021, Qm ∼71, Tc ∼240.5 °C, Pr ∼24.44 μC/cm2 and Ec ∼823.7 V/cm. Furthermore, we employed the tape casting and low-temperature co-fire methods to fabricate a PZT-PZNN/Ag–Pd multilayer piezoceramic of 7 × 7 × 36 mm3 in dimension with a single ceramic film of about 80 μm in thickness. The Ag–Pd electrode is effectively bonded with the ceramic layer, especially chemical binding induced by oxygen diffusion at some partial areas, which plays a crucial role in high binding strength (∼9.2 MPa). The multilayer piezoceramic exhibits outstanding actuating characteristics of high Smax ∼55.53 μm @ 150 V, and low H ∼19.8% @ 150 V together with outstanding stiffness of 70.87 N/μm @ 150 V.

Subsurface Hydride Formation Leads to Slow Surface Adsorption Processes on a Pd(111) Single-Crystal Electrode in Acidic Electrolytes.

Palladium is one of the most important catalysts due to its widespread use in heterogeneous catalysis and electrochemistry. However, an understanding of the electrochemical processes and interfacial phenomena at Pd single-crystal electrodes/electrolytes is still scarce. In this work, the electrochemical behavior of the Pd(111) electrode was studied by the combination of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in different acidic electrolytes, namely, sulfuric acid, perchlorate acid, methane sulfonic acid, and hydrofluoric acid. An analysis of CV profiles shows the strong adsorption of all anions at low electrode potential, partially overlapping with underpotential deposited hydrogen (UPD-H), leading to the appearance of a pair of sharp peaks in what would be considered the "hydrogen region". All anions studied (HSO4-, ClO4-, CH3SO3-, and F-) adsorb specifically and interact with (or effectively block) the surface-adsorbed hydroxyl phase formed on the Pd(111) terrace at higher potentials. Strikingly, the scan rate-dependent results show that the process of anion adsorption and desorption is a kinetically rather slow step. EIS measurements show that the exact mechanism of this slow anion ad/desorption process actually stems from (sub)surface phenomena: the direct hydrogen insertion into Pd lattice (hydrogen subsurface absorption) commences from ca. 0.40 V and leads to the formation of (subsurface) Pd hydrides (PdHx). We argue that the subsurface hydrogen phase significantly alters the work function and thereby the kinetics of the anion adsorption and desorption processes, leading to irreversible peaks in the voltammetry. This precise understanding is important in guiding further fundamental work on Pd single crystals and will be crucial to advancing the eventual design of optimized Pd electrocatalysts.

Control of Carrier Polarity and Schottky Barriers in Layered PdSe2 Field-Effect Transistors

Palladium diselenide (PdSe2) has been discovered as an intriguing two-dimensional (2D) semiconductor for its unique pentagonal crystalline structure, electrical and optical anisotropy, thickness-modulated band gap, robust air stability, and high carrier mobility, demonstrating great potential in field-effect transistors (FETs), photodetectors, and thermoelectric devices. Controlling the carrier polarity and electrical contact Schottky barriers is of great significance for realizing high-performance PdSe2 optoelectronic devices. Here, by combining work-function measurement and electrical transport, we observe a thickness-modulated carrier polarity transition in layered PdSe2 FETs from n-type unipolar to intrinsic ambipolar and p-type unipolar behavior by simply varying the number of layers of PdSe2. Due to the weak Fermi-level pinning in few-layer PdSe2, n-type and ambipolar FETs are achieved by contacting PdSe2 to Sc, Ti, and Pd electrodes, respectively. The Schottky barrier heights are determined by temperature-dependent transport, showing a 15 meV barrier for the Sc contact at the electron side and 62 and 93 meV barriers for Ti and Pd contacts, both at the hole side, respectively. We further demonstrate ozone-treatment-induced hole doping in PdSe2, which effectively converts the PdSe2 FETs from n-type to p-type. The doping is robust in the ambient environment over 3 months. In-plane homojunction on a PdSe2 flake is realized by selective ozone doping, demonstrating typical diode rectifying behavior. The ability to control the carrier polarity and Schottky barriers in layered PdSe2 makes this 2D semiconductor highly feasible for complementary metal-oxide semiconductor device integration and high-performance photodetectors based on atomically thin p–n junctions.

Effects of metallic electrodes on the thermoelectric properties of zigzag graphene nanoribbons with periodic vacancies

We theoretically analyze the thermoelectric properties of graphene quantum dot arrays (GQDAs) with line- or surface-contacted metal electrodes. Such GQDAs are realized as zigzag graphene nanoribbons (ZGNRs) with periodic vacancies. Gaps and minibands are formed in these GQDAs, which can have metallic and semiconducting phases. The electronic states of the first conduction (valence) miniband with nonlinear dispersion may have long coherent lengths along the zigzag edge direction. With line-contacted metal electrodes, the GQDAs have the characteristics of serially coupled quantum dots (SCQDs) if the armchair edge atoms of the ZGNRs are coupled to the electrodes. By contrast, the GQDAs have the characteristics of parallel quantum dots if the zigzag edge atoms are coupled to the electrodes. The maximum thermoelectric power factors of SCQDs with line-contacted electrodes of Cu, Au, Pt, Pd, or Ti at room temperature were similar or greater than 0.186 nW K−1; their figures of merit were greater than three. GQDAs with line-contacted metal electrodes have much better thermoelectric performance than surface contacted metal electrodes.

Computational evaluation of transport parameters and logic circuit designing of L-Lysine amino acid stringed to Au, Ag, Cu, Pt, and Pd electrodes

The integrants of proteins, i.e., amino acids, have grossed exceptional recognition for their applications towards designing imminent switching devices. Among 20 amino acids, L-Lysine (i.e., positively charged) has the highest number of CH2 chains, and such chains affect the rectification ratio in several biomolecules. Towards molecular rectification, we investigate the transport parameters of L-Lysine in conjunction with five different coinage metal electrodes, i.e., Au, Ag, Cu, Pt and Pd to form five distinct devices. We deputize the NEGF-DFT formulism for computing conductance, frontier molecular orbitals, current-voltage, and molecular projected self-Hamiltonian calculations using a self-consistent function. We focus on the most widely used electron exchange correlation combination, i.e., the PBE version of GGA with DZDP basis set. The molecular devices under inquisition exhibit phenomenal rectification ratios (RR) in conjunction with negative differential resistance (NDR) regimes. The nominated molecular device offers a substantial rectification ratio of 45.6 with platinum electrodes and a prominent peak to valley current ratio of 1.78 with copper electrodes. We deduce from these findings that L-Lysine based molecular devices would implicit in future bio-nanoelectronic devices. The OR and AND logic gates are also proposed hinged on highest rectification ratio of L-Lysine-based devices.

Controlled synthesis of Pd–Ag nanowire networks with high-density defects as highly efficient electrocatalysts for methanol oxidation reaction

Pd–Ag bimetallic catalysts containing different molar ratios of Pd/Ag (30/70, 50/50, and 70/30) were prepared using a facile visible-light-assisted liquid-phase method. The samples were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, high-resolution transmission electron microscopy, high-angle annular dark-field scanning transmission electron microscopy, selected-area electron diffraction, and inductively coupled plasma optical emission spectroscopy. Cyclic voltammetry and chronoamperometry measurements were used to evaluate their electrocatalytic properties toward the methanol oxidation reaction (MOR) in alkaline media. The alloyed Pd50Ag50 nanowire network with the optimized molar ratio, which had abundant defects (grain boundaries, lattice dislocations, lattice expansion, and distortion), provided more active sites for the MOR under alkaline conditions. The onset potential of the MOR on the Pd50Ag50-loaded glassy carbon electrode (GCE) was more negative than those on the Pd30Ag70, Pd70Ag30, and pure Pd electrodes. The Pd50Ag50 catalyst showed the best catalytic activity (2853 mA mgPd−1/6.85 mA cmPd−2) compared with those of the pure Pd catalyst (320 mA mgPd−1/2.68 mA cmPd−2) and other samples. This sample also exhibited a high tolerance (ib/if = 0.19) to the poisoning species and long stability (only lost 7.64 % after 500 cycles). The alloyed Pd50Ag50 network is a promising catalyst for the MOR. This work may be extended to construct advanced Pd–M (M = other metals) catalysts for fuel cell applications by surface defect engineering.

Introduction of graphene oxide nanosheets in self-oriented air-stable poly(3-hexylthiophene-2,5-diyl) to enhance the ammonia gas sensing of a p-channel thin film transistor

A self-assembled highly oriented P3HT (Poly(3-hexylthiophene-2,5-diyl))/GO (Graphene oxide) nanocomposite-based p-channel organic field-effect transistor (OFET) for real-time ammonia sensing has been fabricated and characterized on a p++ (highly boron-doped) silicon substrate at room temperature (∼25 °C). A low-cost facile floating film transfer method has been adopted to fabricate the sensing channel of OFET with optimized and uniform thickness (∼25 nm). The electrical characterizations and NH3 sensing performance of the P3HT/GO nanocomposite OFET with palladium electrode have been characterized and compared with pristine P3HT-based OFET. It is demonstrated that the polymer nanocomposite-based OFET with Pd electrode has a relatively high response of ∼63% at 80 ppm NH3 gas. A reduction of 60.41% in field-effect mobility (0.0551 cm2/ V. sec. to 0.02181 cm2/V. sec.) and a 29.4% change in threshold voltage (−4.758 V to −6.157 V) has been observed by varying the NH3 gas concentration over 0–80 ppm. It has an improved response time of ∼44 s and recovery time of ∼82 s due to improved crystallinity and grain size of the sensing layer. All the electrical characterizations and sensing measurements have been done at RT and 55% relative humidity.

Alkaline ethanol oxidation on porous Fe/Pd–Fe nanostructured bimetallic electrodes

In this work, to prepare nanostructured and porous Fe/Pd–Fe bimetallic catalysts, the iron coating is applied firstly onto the copper substrate by the electrochemical deposition method. Subsequently, iron-zinc alloy coating is deposited on the underlayer iron. Eventually, by immersing this alloy coating in an alkaline solution containing palladium ions, the palladium will replace the zinc, resulting in porous Fe/Pd–Fe catalysts. The X-ray diffraction (XRD) technique was used for the characterization of the physical properties of the as-prepared electrocatalysts. Their electrocatalytic activity was studied by electrochemical methods such as cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). The XRD results showed that the zinc element was the main component of the Fe/Zn-Fe alloy and was replaced by palladium as a result of leaching-galvanic replacement. The electrochemical investigations showed that a new porous Fe/Pd-Fe bimetallic catalyst had higher electro-catalytic activity and stability than pure Pd and Fe electrodes for ethanol electro-oxidation in alkaline media. The superiority of the Fe/Pd–Fe catalyst is related to the high surface area and a synergistic effect between Fe and Pd in Fe/Pd–Fe catalysts. Therefore, the nanostructured Fe/Pd–Fe catalysts can be proposed as potential anode materials for alkaline ethanol fuel cells. A new porous Fe/Pd–Fe bimetallic catalyst shows higher electro-catalytic activity and stability than pure Pd and Fe electrodes for ethanol electro-oxidation in alkaline media. The superiority of the Fe/Pd–Fe catalyst is related to the high electrochemical surface area and a synergistic effect between Fe and Pd in Fe/Pd–Fe catalysts

Ab initio study of water dissociation on a charged Pd(111) surface.

The interactions between molecules and electrode surfaces play a key role in electrochemical processes and are a subject of extensive research, both experimental and theoretical. In this paper, we address the water dissociation reaction on a Pd(111) electrode surface, modeled as a slab embedded in an external electric field. We aim at unraveling the relationship between surface charge and zero-point energy in aiding or hindering this reaction. We calculate the energy barriers with dispersion-corrected density-functional theory and an efficient parallel implementation of the nudged-elastic-band method. We show that the lowest dissociation barrier and consequently the highest reaction rate take place when the field reaches a strength where two different geometries of the water molecule in the reactant state are equally stable. The zero-point energy contributions to this reaction, on the other hand, remain nearly constant across a wide range of electric field strengths, despite significant changes in the reactant state. Interestingly, we show that the application of electric fields that induce a negative charge on the surface can make nuclear tunneling more significant for these reactions.

SARS‐CoV‐2 N Gene‐Targeted Anodic Stripping Voltammetry Sensor Using a Novel CoS‐NGQD/Pt@Pd Platform and Au‐DNA‐CdTe QD Probe

AbstractRapid screening of individuals infected with severe acute respiratory syndrome‐coronavirus‐2 (SARS‐CoV‐2) is necessary to contain contagion in a large population. Nucleic acid‐based gold standard assays are time‐consuming, and nucleic acid amplification is mandatory and expensive, impeding the containment of the coronavirus disease 2019 (COVID‐19) outbreak. To overcome the aforementioned disadvantages, this study deals with a specially designed gold (Au)‐deoxyribonucleic acid (DNA)‐cadmium telluride (CdTe) quantum dot (QD) probe to target two sections of the nucleocapsid (N) gene of SARS‐CoV‐2 ribonucleic acid (RNA) of three variants (B.1.1.529, B.1.617.2, and B.1.351). A duplex‐specific nuclease (DSN)‐assisted highly selective release of signaling probes enable higher specificity, and an Au‐supported DNA probe is incorporated to carry many CdTe QD signaling probes. After dissolution, the generated Cd2+ ions are quantified at the novel cobalt sulfide (CoS)‐nitrogen‐doped graphene QD (NGQD)/platinum (Pt)@palladium (Pd) electrode with extraordinary sensitivity through square wave anodic stripping voltammetry (SWASV). The developed sensor exhibits a wide range of detection (10 to 108 copies µL−1) and a lower detection limit (0.12 copies µL−1), without any amplification. The selectivity of the sensor is tested against MERS and HCoV‐NL63, and real‐time detection is performed on heat‐inactivated viral samples, which show excellent selectivity.

Efficient Ohmic Contact in Monolayer CrX2N4 (X = C, Si) Based Field‐Effect Transistors

AbstractDeveloping Ohmic contact systems or achieving low contact resistance is significant for high‐performance semiconductor devices. This work comprehensively investigates the interfacial properties of CrX2N4 (X = C, Si) based field‐effect transistors (FETs) with different metal (Ag, Au, Cu, Ni, Pd, Pt, Ti, and graphene) electrodes by using electronic structure calculations and quantum transport simulations. It is highlighted that the stronger interlayer coupling allows CrC2N4 to form an n‐type Ohmic contact with Ti electrode in the vertical direction. Furthermore, the absence of tunneling barrier at the CrC2N4–Ti interface greatly improves the electron injection efficiency. On the other hand, the studied metals form Schottky contact with CrC2N4 at the lateral interface due to Fermi level pinning (FLP) effects. Surprisingly, the strong FLP effects restrict the Schottky barrier heights of CrSi2N4‐metal contacts to a narrow range. Where Ag, Au, Ni, Pd, Pt, Ti electrodes and Ag, Ti electrodes form ideal ohmic contact with CrSi2N4 in the vertical and lateral directions, respectively, while the other metals form quasi‐ohmic contact. Ti exhibits the highest contact performance as the electrode in both CrC2N4 and CrSi2N4 based FETs. The findings may provide fundamental understanding for designing high‐performance and energy‐efficient FETs based on CrX2N4.

Semi Empirical Evaluation of Shortest Amino acid (i.e., Glycine) as molecular device

This study confirms that Glycine offers strongest coupling with Au(111), Cu(111) and Pt(111) while weakest coupling with Ag(111) and Pd(111) electrodes. Such molecule-electrode coupling is depicted by using projected device density of states, zero bias transmission spectra and conductance curves.

Systematic investigation of the mechanical, electronic, and interfacial properties of high mobility monolayer InAs from first-principles calculations.

Due to the excellent electrostatic control, high mobility, large specific surface area, and suitable direct energy gap of two-dimensional (2D) indium arsenide (InAs), it is regarded as one of the most promising alternative channel materials for next-generation electronic and optoelectronic devices. Recently, 2D semiconducting InAs has been successfully prepared. Based on first-principles calculations, we calculate the mechanical, electronic, and interfacial properties of monolayer (ML) fully-hydrogen-passivated InAs (InAsH2) material. The results show that 2D InAsH2 with excellent stability has a suitable logic device band gap (1.59 eV) comparable to silicon (1.14 eV) and 2D MoS2 (1.80 eV), and the electron carrier mobility of ML InAsH2 (490 cm2 V-1 s-1) is twice as large as that of 2D MoS2 (200 cm2 V-1 s-1). In addition, we study the electronic structure of the interfacial contact characteristics of ML half-hydrogen-passivated InAs (InAsH) with seven bulk metals (Ag, Au, Cu, Al, Ni, Pd, Pt) and two 2D metals (ML Ti2C and ML graphene). 2D InAs was metallized after contact with the seven bulk metals and two 2D metals. Based on the above, we insert 2D boron nitride (BN) between ML InAsH and the seven low/high-power function bulk metals to eliminate the interfacial states. Remarkably, the semiconducting properties of 2D InAs with Pd and Pt electrodes are recovered, and 2D InAs achieves p-type ohmic contact with the Pt electrode, which facilitates high on-current and high-frequency operation of the transistor. Hence, this work provides systematic theoretical guidance for the design of next-generation electronic devices.

Tuning atomic-scale mixing of nanoparticles produced by atmospheric-pressure spark ablation.

Nanoparticles (NPs) mixed at the atomic scale have been synthesized by atmospheric-pressure spark ablation using pairs of Pd and Hf electrodes. Gravimetric analysis of the electrodes showed that the fraction of each material in the resulting mixed NPs can be varied from ca. 15-85 at% to 85-15 at% by employing different combinations of electrode polarities and thicknesses. These results were also qualitatively corroborated by microscopy and elemental analysis of the produced NPs. When using pairs of electrodes having the same diameter, the material from the one at negative polarity was represented at a substantially higher fraction in the mixed NPs regardless of whether a pair of thin or thick electrodes were employed. This can be attributed to the higher ablation rate of the electrodes at the negative polarity, as already known from earlier experiments. When using electrodes of different diameters, the fraction of the element from the thinner electrode was always higher. This is because thinner electrodes are ablated more effectively due to, at least in part, the increased importance of the associated heat losses compared to its thicker counterpart. In those cases, the polarity of the electrodes had a significantly smaller effect. Overall, our results demonstrate, for the first time, that spark ablation can be used to control atomic scale mixing and thus produce alloyed NPs with compositions that can be tuned to a good extent by simply using different combinations of electrode diameters and polarities. This expands the capabilities of the technique for producing mixed nanoparticle building blocks of well-defined composition that are highly desired for a wide range of applications.

Manganese carbonate as an efficient electrocatalyst for the conversion of ammonia (NH4+/NH3) to dinitrogen

Electrochemical deposition of Mn2(CO3)3 on Pd electrode for the oxidation of ammonia (AOR). The Mn2(CO3)3/Pd electrode in 0.5 M NH4OH & 1.0 M Na2CO3 shows high current density of 6.4 mA cm−2 at 1.16 V vs. NHE. The catalyst shows stable activity >4 h.

Nickel carbonate (Ni2(CO3)3) as an electrocatalyst and photo-electrocatalyst for methanol electro-oxidation

Electrochemical deposition of Ni2(CO3)3 on Pt and Pd electrodes for the methanol oxidation reaction has been reported. The Ni2(CO3)3/Pt and Ni2(CO3)3/Pd electrodes show efficient activity for MOR electrochemically as well as photoelectrochemically.

Biosensor based on bimetallic/graphene composite for non-enzymatic detection of hydrogen peroxide in living tumor cells.

A highly sensitive electrochemical biosensor was manufactured with triple synergistic catalysis to detect hydrogen peroxide (H2 O2 ). In this study, a highly sensitive biosensor based on Prussian blue-chitosan/graphene-hemin nanomaterial/platinum and palladium nanoparticles (PB-CS/HGNs/Pt&Pd biosensor) was fabricated for the detection of H2 O2 . The materials described above were modified on the electrode surface and applied to catalyze the breakdown of hydrogen peroxide. The current response of the biosensor presented a linear relationship with H2 O2 concentration from 6 × 10-2 to 20μM (R2 = 0.9766) and with the logarithm of H2 O2 concentration from 20 to 9×103 μM (R2 = 0.9782), the low detection limit of 25nM was obtained at the signal/noise (S/N) ratio of 3. Besides, the biosensor showed an outstanding anti-interference ability and acceptable reproducibility. PB-CS/HGNs/Pt&Pd electrodes are effective in measuring H2 O2 from living tumor cells, which implies that the biosensor has the potential to assess reactive oxygen species in various living tumor cells.

Conduction Mechanism Analysis of Abrupt- and Gradual-Switching InGaZnO Memristors.

In this work, two types of InGaZnO (IGZO) memristors were fabricated to confirm the conduction mechanism and degradation characteristics of memristors with different electrode materials. The IGZO memristor exhibits abrupt switching characteristics with the Pd electrode owing to the formation and destruction of conductive filaments but shows gradual switching characteristics with the p-type Si electrode according to the amount of generated oxygen vacancy. The electrical characteristics and conduction mechanisms of the device are analyzed using an energy band diagram and experimentally verified with random telegraph noise characteristics confirming the trap effects on the device conduction.