The Role of an Inert Electrode Support in Plasmonic Electrocatalysis

Plasmonic nanostructures loaded onto catalytically inert conductive support materials are believed to be advantageous for maximizing photocatalytic effects in photoelectrochemical systems due to the increased efficiency of Schottky barrier-free architectures in collecting hot charge carriers. However, the systematic mechanistic investigation and description of the inert electrode support contribution to plasmonic electrocatalysis is missing. Herein, we systematically investigated the effect of the supporting electrode material on the observed photocatalytic enhancement by comparing photoelectrocatalytic properties of AuNPs supported on highly oriented pyrolytic graphite (HOPG) and on indium tin oxide (ITO) electrodes using electrocatalytic benzyl alcohol (BnOH) oxidation as a model system. Upon illumination, only ~(3 ± 1)% enhancement in catalytic current was recorded on the AuNP/ITO electrodes in contrast to ~(42 ± 6)% enhancement on AuNP/HOPG electrodes. Our results showed that the local heating due to light absorption by the electrode material itself independent of localized surface plasmon effects is the primary source of the observed significant photo-induced enhancement on the HOPG electrodes in comparison to the ITO electrodes. Moreover, we demonstrated that an increased interfacial charge transfer at elevated temperatures, and not faster substrate diffusion is the main source of the enhancement. This work highlights the importance of systematic evaluation of contributions of all parts, even if they are catalytically inert, to the light-induced facilitation of catalytic reactions in plasmonic systems.

Modelling electroforming process under constant bias voltage conditions

In order to understand changes in defect concentration during the electroforming process, we modelled the electroforming process in Ta/HfO2/Pt under constant bias voltage. For this purpose, kinetic Monte-Carlo and finite element methods were utilized. Vacancy profiles were obtained for forming voltages from 3 V to 5 V; modelling of lower stresses is time-consuming. It was found that with decreasing voltage, vacancies begin to accumulate near the inert electrode. When the voltage was dropped from 5 to 3 V, the thickness of such a layer increased by 1 nm, and electroforming time exponentially increase.

Electrolytic production of aluminium. Review. Part 2. Development prospects

This paper looks at the evolution and the current status of inert electrodes. It also describes attempts to design new-generation aluminium cells with wettable cathodes and vertical electrodes. Numerous laboratory studies and pilot tests demonstrate that aluminium cells equipped with inert electrodes are environmentally safe and can deliver a breakthrough technology enabling to bring the power consumption down below 10 kWt·h/kg Al and at the same time increase the production even in the limited capacity of the electrolytic bath. There exists a number of projects aimed at commercializing the inert electrode technology. And despite the apparent loss of interest in this technology on the part of researchers and aluminium producers, relevant pilot tests are scheduled for 2024. A number of alternative innovative power saving cryolite-alumina bath techniques are being discussed, which should allow to get close to the theoretical level of power consumption and provide a dramatic boost in the cell capacity. The paper examines potential application of thermoelectric generators to reduce heat losses, the use of minimum anode-to-cathode distance and vertical nonwettable electrodes, and a transition to 3D electrodeposition of aluminium with cathode polarization.

Chemical Nature of Electrode and the Switching Response of RF-Sputtered NbOx Films

In this study, the dominant role of the top electrode is presented for Nb2O5-based devices to demonstrate either the resistive switching or threshold characteristics. These Nb2O5-based devices may exhibit different characteristics depending on the selection of electrode. The use of the inert electrode (Au) initiates resistive switching characteristics in the Au/Nb2O5/Pt device. Alternatively, threshold characteristics are induced by using reactive electrodes (W and Nb). The X-ray photoelectron spectroscopy analysis confirms the presence of oxide layers of WOy and NbOx at interfaces for W and Nb as top electrodes. However, no interface layer between the top electrode and active layer is detected in X-ray photoelectron spectroscopy for Au as the top electrode. Moreover, the dominant phase is Nb2O5 for Au and NbO2 for W and Nb. The threshold characteristics are attributed to the reduction of Nb2O5 phase to NbO2 due to the interfacial oxide layer formation between the reactive top electrode and Nb2O5. Additionally, reliability tests for both resistive switching and threshold characteristics are also performed to confirm switching stabilities.

Thermal and Chemical Integrity of Ru Electrode in Cu/TaOx/Ru ReRAM Memory Cell

A good candidate for replacing the inert platinum (Pt) electrode in the well-behaved Cu/TaOx/Pt resistive RAM memory cell is ruthenium (Ru), already successfully deployed in the CMOS back end of line. We benchmark Cu/TaOx/Ru device against Cu/TaOx/Pt and investigate the impact of embedment of Cu/TaOx/Ru on two different substrates, Ti(20nm)/SiO2(730nm)/Si and Ti(20nm)/TaOx(30nm)/SiO2(730nm)/Si, on the cell's electrical performance. While the devices show similar switching performance at some operating conditions, there are notable differences at other operation regimes shedding light on the basic switching mechanisms and the role of the inert electrode. The critical switching voltages are significantly higher for Ru than for Pt devices and can be partly explained by the work function difference and different surface roughness of the inert electrode. The poorer switching properties of the Ru device are attributed to the degraded inertness properties of the Ru electrode as a stopping barrier for Cu+ ions as compared to the Pt electrode. However, some of the degraded electrical properties of the Ru devices can be mitigated by an improved integration of the device on the Si wafer. This improvement is attributed to the suppression of crystallization of Ru and its silicidation reactions that take place at elevated local temperatures, present mainly during the reset operation. This hypothesis has been corroborated by extensive XRD studies of multiple layer systems annealed at temperatures between 300K and 1173K.

BEHAVIOR OF BLOCKING (INERT) ELECTRODE / SOLID ELECTROLYTE INTERFACE IN GALVANOGARMONIC CHARGING MODE. CASE OF DECELERATED DIFFUSION AND ADSORPTION –DESORPTION OF TWO DIFFERENT KINDS OF PARTICLES

Electrochemical behavior of a cell with an interface of blocking electrode /solid electrolyte was studied in galvanogarmonic mode of charge. The possibility of application of simple and more graphic calculation technique and separation of electrochemical impedance schemes into active and reactive constituents was shown. The Jacobsen-West diffusion model was used as an equivalent electric circuit, which is valid for relatively large times or low AC frequencies. The plotting of dependences of active and reactive impedance components on AC frequency was used in order to estimate the values of parameters for studied equivalent electric circuits.

KINETICS OF CHARGING INTERFACE OF BLOCKED ELECTRODE-SOLID ELECTROLYTE IN GALVANODYNAMIC AND POTENTIODYNAMIC MODES. CASE OF DELAYED DIFFUSION AND ADSORPTION-DESORBTION OF TWO PARTICLE OF DIFFERENT KIND

The kinetics of charging the blocked (inert) electrode/ solid electrolyte interface was studied by operational impedance method in the galvanodynamic and potentiodynamic modes. For calculations the equivalent electrical scheme of Jacobsen and West method was used which is suitable in the case of long time of charging. The participation of two different electrochemically active particles in a process of delayed diffusion and adsorption-desorption was taken into account.