Anode Substrate Research Articles

Carbon tape-assisted electrodeposition and characterization of arrayed micro-/nanostructures

The template-controlled electrodeposition has been widely used for fabricating arrayed micro-/nanostructures (both metallic and composite), which typically requires the vacuum-deposition of a conductive metal film on the template and faces the challenge of detaching them from the substrate electrode for subsequent characterization/application. Herein we report that such a template-assisted fabrication strategy can be readily accomplished by using double-sided carbon tapes in conjunction with nanoporous templates of choice, which allows for not only simple, rapid assembly with any substrate electrode for the deposition of arrayed micro-/nanostructures with standard electrochemical equipment, but also their effort-less detachment for subsequent characterization and application. As of the proof-of-concept, we have demonstrated that “hemisphere” gold ultramicroelectrode arrays with characteristic redox responses can be reproducibly prepared in a few minutes with appropriate deposition time and potential. The application of this convenient method as a routine, benchtop protocol for preparing different types of arrayed micro-/nanostructures (e.g., Au, Cu, and Pt) using various nanoporous templates (both polycarbonate membranes and anodic aluminum oxide substrates) via conventional electrochemical deposition has been also described.

Nano-PAA-CuCl2 Composite as Fenton-Like Reusable Catalyst to Enhanced Degrade Organic Pollutant MB/MO

The treatment of organic dye contaminants in wastewaters has now becoming more imperative. Fenton-like degradation of methylene blue (MB) and methyl orange (MO) in aqueous solution was investigated by using a nanostructure that a layer of CuCl2 nanoflake film grown on the top surface of nanoporus anodic alumina substrate (nano-PAA-CuCl2) as catalyst. The new nano-PAA-CuCl2 composite was fabricated with self-assembly approach, that is, a network porous structure film composed of CuCl2 nanoflake grown on the upper surface of nanoporous anodic alumina substrate, and the physical and chemical properties are characterized systematically with the X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), and high-resolution transmission electron microscopy (HRTEM), Energy Dispersive Spectrometer (EDS), X-ray photoelectron spectroscopy (XPS). The experimental results showed that the nano-PAA-CuCl2 catalyst presented excellent properties for the degradation of two typical organic pollutants such as MB and MO, which were almost completely degraded with 8 × 10−4mol/L nano-PAA-CuCl2 catalyst after 46 min and 60 min at reaction conditions of H2O2 18 mM and 23 mM, respectively. The effects of different reaction parameters such as initial pH, H2O2 concentration, catalyst morphology and temperature were attentively studied. And more, the stability and reusability of nano-PAA-CuCl2 were examined. Finally, the mechanism of MB and MO degradation by the nano-PAA-CuCl2/H2O2 system was proposed, based on the experimental data of the BCA and the temperature-programmed reduction (H2-TPR) and theoretical analysis, the reaction kinetics belonged to the pseudo-first-order equation. This new nanoporous composite material and preparation technology, as well as its application in Fenton-like reaction, provide an effective alternative method with practical application significance for wastewater treatment.

Microhotplates based on Pt and Pt-Rh films: The impact of composition, structure, and thermal treatment on functional properties

Recent progress in portable semiconductor and thermocatalytic gas sensors requires the development of the microhotplates with reduced power consumption, increased shock resistance, and low resistance drift. Rh is known as alloying component, which allows one to decrease the diffusion mobility of Pt in bulk resistive heating elements. Here, a comparison study on the stability of microhotplates based on Pt and Pt-Rh thin films is performed. The porous anodic alumina is used as a substrate, which provides high adhesion of the metal film and the thermal expansion coefficient compatible with Pt and Pt-Rh alloys. Morphology and crystal structure of metal films are studied after recrystallization annealing in air at the temperatures 600–810 °C. To simulate thermal effects of the microhotplates, a model based on the finite element method is developed. The perspectives of Pt-11 % Rh alloy as a material for microhotplates operating at the temperatures above 500 °C are discussed. The achieved characteristics of the fabricated Pt-Rh microhotplates on porous anodic alumina substrates allow one to use them as a universal platform for semiconductor and thermocatalytic gas sensors manufacturing.

Stability improvement for dried droplet pretreatment by suppression of coffee ring effect using electrochemical anodized nanoporous tin dioxide substrate.

A novel nanoporous analytical platform is reported to improve the stability of the dried droplet method (DDM). This nanoporous platform was made of tin dioxide (Np SnO2) substrate by electrochemical anodization from tin (Sn) slide. The DDM is a widely used sample pretreatment in analytical chemistry that involves placing a droplet of solution onto the substrate and drying for analytical testing. However, during the droplet drying process, the solutes would converge at the droplet edge and cause inhomogeneous solutes distribution. This is the coffee ring effect (CRE). The Np SnO2 has irregular nanopores, which allows droplet solutions to penetrate into the substrate rather than spreading out, effectively suppressing CRE. Theoretical models were built to explain the formation of CRE on blank tin (Sn) substrate and suppression of CRE on Np SnO2. Better results were obtained in detecting lithium (Li) using the Np SnO2 by laser-induced breakdown spectroscopy (LIBS). The line scanning results indicated that the Li emission line (670.8nm) intensities on Np SnO2 substrate had lower relative standard deviation (RSD = 3.3%) than those on Sn substrate (RSD = 31.5%), which illustrate suppression of CRE and stability improvement on Np SnO2 substrate. Furthermore, Licalibration curves were built for LIBS with DDM. The curve using Np SnO2 substrate had better linearity (R2 = 0.997), higher precision (RSD = 4.2%), and higher sensitivity (LOD = 0.13mg/L) than that by Sn substrate (R2 = 0.954, RSD = 17%, and LOD = 1.21mg/L). All in all, the anodic Np SnO2 substrate can suppress CRE in DDM and hence improve the stability and precision of subsequent analysis. Graphical abstract.

Insight into atmospheric corrosion evolution of mild steel in a simulated coastal atmosphere

The corrosion behavior of mild steel in a simulated coastal atmosphere environment has been investigated by the indoor accelerated wet/dry cyclic corrosion acceleration test (CCT), scanning electron microscopy (SEM), Raman spectroscopy and electrochemical measurements. During the CCT test of 60 cycles, the evolution of logarithmic (corrosion rate) vs. logarithmic (CCT cycles) presents a turning point at the 5th cycle, presenting a tendency to increase first and then decrease to gradually stabilize as the CCT cycle prolonged. Before the 5th cycle, γ-FeOOH and β-FeOOH and Fe3O4 were detected, respectively. And then, α-FeOOH as a new chemical composition was detected in the subsequent corrosion cycles. It is found that, after long term corrosion, the rust separated into a relatively dense inner layer rich with α-FeOOH and a loose outer layer rich with γ-FeOOH, both of which have poor electrical conductivity. The rapid increase of corrosion rate in the early stage since reducible corrosion products are involved in the reduction process of the cathode which promotes the dissolution of the anodic metal substrate. Afterward, as the rust layer thickens, the resistance of the rust increases, and the aggressive ions diffusion is blocked, gradually suppressing the electrochemical corrosion process. At last, when the composition and distribution of the rust layer remain stable, the corrosion presents a fluctuating speed around a certain value during the cracking and self-repairing process of the rust layer.

Calculation of Temperature Conditions of a Plasma Sputtering Cell for Decontamination of Nuclear Power Plant Constructions

We are developing a technology for the “dry” deactivation of nuclear power plant (NPP) constructions by ion sputtering of surfaces with microsized radioactive contaminants. Our technology is implemented by plasma discharge in an inert gas medium with mass transfer of sputtered material and its deposition in the diffusion mode on the anode substrate. In our technology, unlike traditional radiochemical methods, radionuclides do not transfer into liquid radioactive waste (LRW), but condense in a compact solid form, which makes it possible to use them. Since our technology can be applied both during decommissioning of NPPs (including deactivation of neutron-irradiated nuclear graphite) and during routine operation and scheduled repairs of nuclear reactors, it is possible to extract the necessary isotope concentrate in the required quantities using an intense neutron flux in the NPP. The design of a plasma sputtering cell to remove radionuclides from the irradiated graphite and the NPP construction surfaces involves ignition of a direct current plasma discharge in an inert gas (for example, argon) at a pressure P ~ 0.1–1 atm and control of the temperature conditions of the sputtering material deposition. In this paper, the temperatures of the anode (tantalum collector) and the cathode (sputtered graphite) have been calculated depending on the input power to the argon plasma discharge. Data on the temperatures of the cathode and anode (collector) surfaces make it possible to control the elemental composition of the sputtered atoms and to form nanoscale layers of radionuclide concentrate on collector for use in radiation medicine and new betavoltaic batteries. Thus, the technology is important not only for the deactivation of NPPs but also for the formation of nanoscale layers of beta-active materials.

In situ demonstration of anodic interface degradation during water electrolysis: Corrosion and passivation

Understanding of interface-driven performance degradation in the oxygen evolution reaction (OER) is a prerequisite for developing long-term electrolytic systems operating at maximum efficiency. The question remains as to whether in situ observation of degradation during OER will be possible. We design a model system and fabricate a structure that is ideal for in situ detection of interfacial degradation that could occur at the anode, i.e. corrosion and passivation. The synthesized structure is based on carbon (C) or non-carbon (Ti); this is not only because it is a practical and general choice as an anode substrate, but also because it can represent the degradation reaction of corrosion or passivation, respectively. Interfacial responses from the ideally structured surface are observed (spectro)electrochemically under OER-operating conditions. We reveal that while electrochemical oxidation of C is inevitable over time, the passivation of Ti can be circumvented under controlled conditions. We also disclose that the use of Ti can be more beneficial for electrolytic cells, than that of C. These results highlight future research strategies required for the optimization of C- and Ti-based components used in electrolytic cells.

Microstructural and electrochemical properties of impregnated La0.4Sr0.6Ti0.8Mn0.2O3±d into a partially removed Ni SOFC anode substrate

The microstructural and electrochemical properties of anodes obtained by impregnation of the La0.4Sr0.6Ti0.8Mn0.2O3±d (LSTM) oxide system into two types of anode substrates such as Ni/ 8YSZ substrate (Ni (E)/ 8YSZ) and partially Ni removed Ni/ 8YSZ substrate (Ni(R)/8YSZ) were investigated in order to apply them as anode material for solid oxide fuel cells.All of the samples with LSTM impregnated on Ni (R)/ 8YSZ show higher electrical conductivity values than those of unimpregnated Ni (E)/ 8YSZ under dry H2 condition. The highest electrical conductivity values of 2041.2, 1877.4, and 1764.3 S/cm at 700, 800 and 900 °C can be achieved by samples with 3 wt% impregnated LSTM on Ni (R)/ 8YSZ. From the XPS analysis, the existence of a Ti metal peak on the surface of LSTM was only measured for the LSTM (3 wt%)-Ni (R)/ 8YSZ sample, metallic titanium on the surface can improve the electrical catalytic reaction.LSTM (3 wt%)-Ni (R)/ 8YSZ showed higher electrical conductivity values then those of LSTM (3 wt%)-Ni (E)/ 8YSZ in all the temperature ranges measured in the case of dry CH4 supply. Finally, the electrical conductivity of LSTM (3 wt%)-Ni (R)/ 8YSZ was stably maintained even when exposed to dry CH4 condition at 900 °C for a long time (100 h).

Modeling the influence of substrate concentration, anode electrode surface area and external resistance in a start-up on the performance of microbial fuel cell

In the present research, the conduction-based model was used for investigating influence of anode surface area, substrate concentration and start-up method on the performance of microbial fuel cells (MFC), utilized in wastewater treatment systems. Maximum produced power increased by about 9% when external resistance enhanced from 100 to 1000 Ω in the start-up. The results show that power increased rapidly (from 0.024 to 3.66 mW) with increasing the initial chemical oxygen demand (COD) of substrate from 0.01–2 g/L. However, when COD was increased from 2 to14 g/L, produced power remained almost constant (3.66–3.81 mW). The surface area of the anode had a different effect on power and power density. Produced power enhanced by increasing surface area of the anode. However, the effect of surface area of anode on power density was different and had an optimum value, which increased in higher COD concentrations.

Direct laser-induced deposition of AgPt@C nanoparticles on 2D and 3D substrates for electrocatalytic glucose oxidation

We present a new approach for the preparation of electrocatalytically active carbonaceous coatings embedding bimetallic nanoparticles (NPs) - AgPt@C structures, on surfaces with 2D and 3D geometry such as glass covered with indium tin oxide (ITO) film and anodic aluminum oxide substrates, respectively. We provide extensive characterization of the deposited structures and demonstrate their performance towards the electrocatalytic glucose oxidation, one half-reaction of biofuel cells. We observe that a preliminary surface treatment of the porous alumina substrate is essential for a homogeneous laser-induced deposition of AgPt@C nanoparticles across the whole pore depth.

Facile one-step fabrication of super-repellent nanoporous anodic alumina using a non-fluorinated approach

Inspired by lotus-effect, superhydrophobicity has attracted considerable interest in various areas such as self-cleaning, antifouling and liquid transportation, and so on. Superhydrophobic surfaces can be prepared mostly by altering the surface with creating micro/nanoscale structures or with chemically modifying by materials of low surface energy. In this study, the electrochemically fabricated nanoporous alumina is deposited with poly(dimethylsiloxane) via a one-step thermal treatment to achieve ultra-water repellent or superhydrophobic surfaces. Nanoporous anodic alumina substrates with varying pore diameters were used for the poly(dimethylsiloxane) deposition, and their morphological characterization is carried out using the field emission scanning electron microscope. Energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy inferred the chemical composition, while contact angle measurements using a commercial contact angle measurement system is exploited to probe the water spreading behaviour on the fabricated substrates. The substrates also exhibit high repellence behaviour towards ethylene glycol. The superhydrophobic behaviour of the fabricated substrates is investigated while the substrate is immersed in organic solvents like decane, hexane and toluene. In addition, the super repellence behaviour of the substrates against the corrosive chemicals such as aqua regia and saturated sodium hydroxide is investigated and the substrate was found to retain its super repellence behaviour against corrosive solutions. Further, the self-cleaning properties and antifouling behaviour of the fabricated substrates were also demonstrated.

Rapid laser reactive sintering of BaCe0.7Zr0.1Y0.1Yb0.1O3-δ electrolyte for protonic ceramic fuel cells

The state-of-the-art protonic ceramic electrolyte BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3-δ (BCZYYb) dense films were successfully deposited on the pre-sintered Ni(O)+BCZYYb anode substrate by recently developed rapid laser reactive sintering (RLRS) method. The separation of the deposition of dense electrolyte from the preparation of porous anode makes it possible to manufacture protonic ceramic fuel cells (PCFCs) with more desirable electrolyte and anode microstructures. The PCFC single cells prepared after introducing the cathode thin film BaCo 0.4 Fe 0.4 Zr 0.1 Y 0.1 O 3-δ (BCFZY0.1) showed OCVs of 0.94–0.97V and peak power densities of 97 mW/cm 2 at 600 °C and 121 mW/cm 2 at 600–650 °C under Air/H 2 gradient. The proton conductivity of the BCZYYb film derived the RLRS-derived single cell showed a moderate proton conductivity of 3.7 × 10 −3 S/cm at 600 °C. The higher PCFC performance can be expected by further optimization of the thickness, compositions, and/or microstructures of the component layers. Rapid laser reactive sintering deposited a dense BCZYYb electrolyte on a pre-sintered BCZYYb ​+ ​Ni(O) anode, which allowed the independent fabrication of each component layer for PCFCs to achieve desired structures for high performance. • Rapid laser reactive sintering (RLRS) can make dense electrolyte on sintered anode. • RLRS-derived electrolyte shows a moderate proton conductivity. • RLRS can provide knowledge to the rapid additive manufacturing of ceramics. • RLRS allows independent control of microstructures of fuel cell component layers.

Graphene-Based Ion Sensitive-FET Sensor With Porous Anodic Aluminum Oxide Substrate for Nitrate Detection

In this paper, we report an ion sensitive field effect transistor (IS-FET) sensor on anodic aluminum oxide (AAO) substrate, which can directly detect nitrate in water without a buffer solution. The free-standing AAO substrate has a highly ordered porous structure, which supports graphene and Au electrodes. The AAO substrate increases the exposed area of graphene in water. We describe the surface structure of the AAO substrate with scanning electron microscopy in each fabrication process. The device structure and mechanism are also explained in the paper. Graphene is used for the sensing material for its sensitivity in response to the surroundings. The nitrate selective membrane is synthesized and applied to the surface of graphene. The performance of the IS-FET sensors is characterized by a semiconductor analyzer. In the results, the performance of the device is significantly enhanced due to the porous structures of AAO. We successfully demonstrate the superior sensitivity and selectivity of the sensors. The detection limit is 0.05 ppm, and the response time is less than 3 seconds. [2020-0131]

Lithiophilic Li-Zn alloy modified 3D Cu foam for dendrite-free lithium metal anode

Three-dimensional (3D) materials are the potential promising lithium (Li) metal anode (LMA) substrates for alleviating volume expansion and inhibiting dendrite formation in high energy density battery systems. Herein, we propose a 3D substrate functioned with Li-Zn lithiophilic alloy surface through lithiation of the electrochemically deposited Zn on Cu foam (3D Li-Zn@Cu foam). This substrate can induce uniform Li deposition along the conductive skeleton, effectively reduce the Li nucleation overpotential and suppress Li dendrite formation. As a result, this substrate exhibits an excellent coulombic efficiency (CE) of 97.8% for 260 cycles at 1 mA cm−2, and with dendrite-free morphology at ultrahigh cycling capacity of 10 mAh cm−2. Symmetric cells with Li-deposited Li-Zn@Cu foam (Li@Li-Zn@Cu foam) electrode can be stably operated over twice lifespan than that of Li@Cu foam. Furthermore, full cells paired with LiFePO4 or sulfur cathodes exhibit remarkable discharge capacities and capacity retention. It is well confirmed that the Li-Zn alloy coating method provides a new light on modifying the surface of 3D skeleton materials for dendrite-free LMA.

Optical Properties of Zno + 12% ITO Thin Films on Substrates of Anode Aluminum Oxide

ZnO thin films of zinc oxide doped with 12 % ITO (indium tin oxide) on anodic aluminum oxide substrates are formed in vacuum during high-frequency repetitively pulsed laser deposition. The morphology of films on porous and nonporous surfaces of substrates was studied by atomic force microscopy. The optical properties of the films in the visible, near, and middle IR regions of the electromagnetic radiation spectrum, the Raman spectra, and also the features of the photoluminescence characteristics have been experimentally investigated. Zinc oxide films can be used in optoelectronic transducers, as luminescent material, in the form of transparent electrodes, sensitive layers of gas and biological sensors, catalysts, X-ray and gamma-radiation detectors.

Fabrication of Compositionally Gradient Anode Functional Layer for Proton Conducting Fuel Cell at Intermediate Temperatures: A Preliminary Study

In this work, an anode-supported button cell was fabricated with compositionally gradient (CG) NiO-BaCe0.54Zr0.36Y0.1O2.95 (NiO-BCZY) anode functional layer (AFL). The button cell has a configuration of NiO-BCZY (50:50) | NiO-BCZY (30:70) | NiO-BCZY (10:90) | BCZY | LSCF. All powder materials were synthesized using a sol-gel method. Firstly, NiO-BCZY anode substrate was fabricated using dry-pressing method. Next, NiO-BCZY CG-AFL and BCZY electrolyte thin film were spin-coated on the anode substrate and lastly the La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) cathode was spin-coated on the electrolyte thin film. The microstructure of the fabricated button cell with good adhesion between all the layers, thin and dense electrolyte layer, and gradient increase in density of materials from anode substrate to electrolyte were observed using Scanning Electron Microscopy (SEM). Cell’s performance in terms of resistivity was evaluated using Electrochemical Impedance Spectroscopy (EIS) and conductivity meter using four-point probe method. Values of ohmic (Ro) and polarization resistance (Rp) of the cell are 7.3 and 2.4 Ωcm2 at 700 °C, respectively. The lower resistance values obtained compared to our previous work on a conventional 3-layers BCZY-based single button cell (Ro = 9.6 and Rp = 7.8 Ωcm2 at 700 °C) confirmed the functionality of GC-AFL in enhancing the cell’s performance. This preliminary result shows that simple deposition technique of CG-AFL plays a significant role in the optimization of PCFC button cell designs and electrochemical performance.

Effects of Co2+ in diaphragm electrolysis on the electrochemical and corrosion behaviors of Pb[sbnd]Ag and Pb anodes for zinc electrowinning

In this study, the influence of Co2+ (2 g/L) on the electrochemical behavior of cast Pb−Ag (0.6 wt%) anode and cast Pb anode was investigated in diaphragm electrolysis by galvanostatic polarization, cyclic voltammetry, and anodic polarization and with Tafel curves. In addition, analyses of the anodic weight loss, metal ion concentration, phase analysis, and scanning electron microscopy images of the oxide layer and substrate were also conducted. The results show that the diaphragm electrolysis cell completely prevented the metal ions in the anode chamber from penetrating into the cathode chamber. The Co2+ in the solution was gradually oxidized to Co3+ during the oxygen evolution reaction (OER), which facilitated the reduction of the potential of the OER, decreased the time for the potential of the Pb−Ag (0.6 wt%) anode and Pb anode to stabilize, and improved the corrosion resistance of the Pb−Ag (0.6 wt%) anode and Pb anode by weakening the oxidation of the anodic metal substrate during the OER.

A quick start method for microbial fuel cells

Microbial fuel cells (MFCs) have great potential to detect toxicity early. Study of toxicity sensors based on MFCs requires a large number of stable MFCs. However, the start-up time of MFCs is generally long, which limits research progress. In this study, a first-stage preculture based on H-type MFCs (first culture) and a second-stage preculture based on multistage MFC reactor series culture (second culture) were used in combination with preculture MFCs. The goal of obtaining an MFC with stable performance in only one day was achieved. The obtained MFC could be stable for 33 h and rapidly regenerated with replacement of the anode substrate. The start-up time was shortened because after the first culture and the secondary culture, the protein content attached to the electrode reached 1.2864 ± 0.0174 mg/cm2 and 2.22 ± 0.12 mg/cm2, respectively. Bacteria that generate electricity, such as Geobacter, were effectively enriched. This study may improve the development efficiency of MFC toxicity sensors.

Phenol-acclimated activated sludge and Ralstonia eutropha in a microbial fuel Cell for removal of olive oil from mill wastewater

The fuel acclimation process offers flexibility in microbial fuel cell (MFC) power generation behavior. Different concentrations (50–200 mg/L) of phenol were used for adapting the activated sludge (AS), obtained from a local petroleum wastewater treatment plant and Ralstonia eutropha pure culture. Anodic biomass capable of oxidizing phenol substrate, using either AS inoculum microbial consortium or R. eutropha in the MFC system, has been a reflection of growth supportive functionality of phenol and 150 mg/L as initial concentration was used in the experiments. For both types of inocula. The results of phenol and COD removals obtained for closed system configuration were compared with those under open circuit condition. The current production by AS and R. eutropha was improved through phenol acclimation process. The highest power density (PD) using either AS or R. eutropha was 11 and 5.8 mW/m2, respectively. In terms of using olive oil mill wastewater as the anodic substrate, the behavior of phenol-acclimated R. eutropha was better than that of the synthetic type of wastewater, and the PD value was 7.8 mW/m2.

Fabrication of a Silica–Silica Nanoparticle Monolayer Array Nanocomposite Film on an Anodic Aluminum Oxide Substrate and Its Optical and Tribological Properties

The fabrication and properties of silica nanoparticle monolayer arrays (SNMAs) immobilized on silica films on nanoporous anodic aluminum oxide (AAO) substrates by polymerization of silicic acid and a two-step spin-coating technique are reported. Reflection spectra of the obtained silica-SNMA nanocomposite films on AAO substrates were almost the same as those of the original AAO substrate. The coefficient of friction at an applied load of 0.98 N under dry conditions for a film fabricated under optimal conditions was significantly decreased by 76% with respect to that without a silica-SNMA nanocomposite film on an AAO substrate. The results also showed a lower coefficient of friction than that for MoS2 nanoparticles (commonly used for self-lubricating films) deposited on an AAO substrate. We demonstrate that the silica-SNMA nanocomposite film with an optimal nanoroughness, thickness, and wear resistance can be used as a novel coating film for AAO substrates with both a high color degree of freedom and a low coefficient of friction at a high applied load (ca. 1 N).