Origins of the Instability of Non-precious HER Catalysts at Open Circuit Potential

Non-precious hydrogen evolution reaction (HER) catalysts commonly suffer from severe dissolution under open circuit potential (OCP). In this work, using calculated Pourbaix diagrams, we quantitatively analyze the stability of a set of well-known active HER catalysts (MoS2, MoP, CoP, Pt in acid, and Ni3Mo in base) under working conditions. We determine that the large thermodynamic driving force towards decomposition created by the electrode/electrolyte interface potential is responsible for the substantial dissolution of non-precious HER catalysts at OCP. Our analysis further shows the stability of HER catalysts in acidic solution is ordered as Pt ∼ MoS2 > MoP > CoP, which is confirmed by the measured dissolution rates using an inductively coupled plasma mass spectrometer. Based on gained insights, we suggest strategies to circumvent the catalyst dissolution in aqueous solution.

Download Full-text

Stability of Bioactivated Co-Cr Alloys in Biological Environment

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.361-363.737 ◽

2007 ◽

Vol 361-363 ◽

pp. 737-740 ◽

Cited By ~ 2

Author(s):

M.M. Sovar ◽

C. Ducu ◽

D. Iordachescu ◽

Ioana Demetrescu

Keyword(s):

Inductively Coupled Plasma ◽

Open Circuit ◽

X Ray ◽

Inductively Coupled ◽

Cyclic Voltametry ◽

Icp Ms ◽

Plasma Mass Spectrometry ◽

Biological Environment ◽

The Stability ◽

Electronic Microscope

The present work is focused on the stability of bioactivated CoCr alloy in biological environment (buffered saline solution (PBS), lactic acid, citric acid). The chemical and electrochemical deposition was characterized by electrochemical methods (open circuit potential, cyclic voltametry), scanning electronic microscope (SEM), x-ray diffractometer (XRD), inductively coupled plasma/mass spectrometry (ICP/MS) and citotoxicity test. The results prove a good electrochemical stability in all cases.

Download Full-text

Potentiometric Response of Ag/AgCl Chloride Sensors in Model Alkaline Medium

Advances in Materials Science and Engineering ◽

10.1155/2018/8135492 ◽

2018 ◽

Vol 2018 ◽

pp. 1-12 ◽

Cited By ~ 2

Author(s):

Farhad Pargar ◽

Hristo Kolev ◽

Dessi A. Koleva ◽

Klaas van Breugel

Keyword(s):

Alkaline Medium ◽

Open Circuit Potential ◽

Dynamic Equilibrium ◽

Chloride Concentration ◽

Chloride Content ◽

Cementitious Materials ◽

Open Circuit ◽

Potentiometric Response ◽

Before And After ◽

The Stability

The stability and reproducibility of an Ag/AgCl sensors’ response in an alkaline medium are important for the application of these sensors in cementitious materials. The sensors’ response, or their open circuit potential (OCP), reflects a dynamic equilibrium at the sensor/environment interface. The OCP response in an alkaline medium is affected by the presence of hydroxide ions. The interference of hydroxide ions leads to inaccuracies or a delay in the sensors’ response to a certain chloride content. In this article, the potentiometric response (or OCP evolution) of the chloride sensors is measured in model solutions, resembling the concrete pore water. The scatter of the sensors’ OCP is discussed with respect to the interference of hydroxide ions at varying chloride concentration in the medium. The deviation of the sensor’s response from its ideal performance (determined by the Nernst law) is attributed to dechlorination of the AgCl layer and the formation of Ag2O on the sensor’s surface. Results from the surface XPS analysis of the AgCl layer before and after treatment in alkaline medium confirm these observations in view of chemical transformation of AgCl to Ag2O.

Download Full-text

Nanocomposite Detection of Elemental Impurities and Process Correlation Analysis of Ceftriaxone Sodium for Injection

Nanoscience and Nanotechnology Letters ◽

10.1166/nnl.2020.3261 ◽

2020 ◽

Vol 12 (12) ◽

pp. 1458-1463

Author(s):

Li Zhu ◽

Xiaomeng Chong ◽

Yu Zhao ◽

Mingzhe Xu ◽

Lihui Yin

Keyword(s):

Activated Carbon ◽

Generic Drug ◽

Inductively Coupled Plasma ◽

Plasma Spectroscopy ◽

Inductively Coupled ◽

Elemental Impurities ◽

Ceftriaxone Sodium ◽

The Stability ◽

Impurity Elements ◽

First Time

An inductively coupled plasma spectroscopy method was established to detect 29 elemental impurities in ceftriaxone sodium for injection by nanocomposite, and also used to detect the elemental impurities in the generic, domestic original and foreign original ceftriaxone sodium for injection. This paper for the first time analysed the possible sources of elemental impurities and their potential impacts on the drug quality based on the process. The results showed that zinc and potassium were detected in both the generic drug and the domestic original ceftriaxone sodium for injection, and zinc was not detected but potassium was detected in the foreign original drug; the content of zinc in the generic drug was significantly higher than that in the domestic original drug, and the content of potassium in generic drug and domestic original drug was higher than that in the foreign original drug, according to the process, the elemental impurities may come from the activated carbon or nanocarriers used in the process, and further stability analysis of the samples showed that the stability of the generic drug was slightly lower than that of the original drug, so it was speculated that impurity elements might also be one of the reasons for its instability.

Download Full-text

Instability of Si3N4/, SiC/, and MoSi2/ethanol suspensions

Journal of Materials Research ◽

10.1557/jmr.2003.0007 ◽

2003 ◽

Vol 18 (1) ◽

pp. 45-52 ◽

Cited By ~ 1

Author(s):

Yoko Fukada ◽

Patrick S. Nicholson

Keyword(s):

Photoelectron Spectroscopy ◽

Inductively Coupled Plasma ◽

Ammonium Hydroxide ◽

Inductively Coupled ◽

Transmission Electron ◽

Tetramethyl Ammonium Hydroxide ◽

Powder Addition ◽

The Stability ◽

Insight Into

Time-dependent suspension behavior is reported for nonoxide ceramic powders (Si3N4, SiC, and MoSi2) in ethanol. The suspension pH (and therefore the stability) changed with time. X-ray photoelectron spectroscopy, inert gas fusion, inductively coupled plasma, and high-resolution transmission electron microscopy were used to track changes of surface chemistry. The adsorption of the base, tetramethyl ammonium hydroxide (TMAH), is examined. The pH drop on powder addition to pure EtOH was used to gain insight into the role of TMAH coverage of the powder surfaces.

Download Full-text

Analysis for the stability of platinum-containing species in soil samples using capillary electrophoresis interfaced on-line with inductively coupled plasma mass spectrometry

Electrophoresis ◽

10.1002/elps.1150180204 ◽

1997 ◽

Vol 18 (2) ◽

pp. 196-201 ◽

Cited By ~ 43

Author(s):

Bernhard Michalke ◽

Sönnke Lustig ◽

Peter Schramel

Keyword(s):

Mass Spectrometry ◽

Capillary Electrophoresis ◽

Inductively Coupled Plasma ◽

Soil Samples ◽

Inductively Coupled ◽

Plasma Mass Spectrometry ◽

On Line ◽

The Stability

Download Full-text

Comparative Study of Structure and Pickling Characteristics of Oxide Scale Formed on Strips Produced by TSCR and Conventional Process

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.228-229.77 ◽

2011 ◽

Vol 228-229 ◽

pp. 77-82

Author(s):

L. M. Zhu ◽

J. H. Yang

Keyword(s):

Oxide Scale ◽

Open Circuit Potential ◽

Steel Strip ◽

Open Circuit ◽

Conventional Process ◽

Pickling Solution ◽

Magnetite Fe3o4 ◽

Structure Observation ◽

The Stability ◽

Hematite Fe2o3

The microstructure and pickling characteristics of oxide scale formed on hot-rolled SPHC steel strip produced by different processes were investigated based on structure observation, weight loss and corrosion potential measurements. The results show that the scale formed on strip produced by TSCR consists of mainly magnetite (Fe3O4) and little wustite (FeO), hematite (Fe2O3), and that in conventional process is composed mainly wustite (FeO) and little magnetite (Fe3O4), hematite (Fe2O3). The shape of the open-circuit potential transient is determined crucially by the oxide scale structure. Time to reach a steady-state value of open-circuit potential of strip produced by TSCR is longer than that in conventional process. Both the stability of the scale in pickling solution and the effectiveness of descaling could be evaluated and predicted by measuring the change of electrochemical potential during acid pickling.

Download Full-text

Reaction of Gold Substrates with Diazonium Salts in Acidic Solution at Open-Circuit Potential

Langmuir ◽

10.1021/la902002n ◽

2009 ◽

Vol 25 (23) ◽

pp. 13503-13509 ◽

Cited By ~ 61

Author(s):

Joshua Lehr ◽

Bryce E. Williamson ◽

Benjamin S. Flavel ◽

Alison J. Downard

Keyword(s):

Open Circuit Potential ◽

Acidic Solution ◽

Open Circuit ◽

Diazonium Salts ◽

Gold Substrates

Download Full-text

Understanding the Crucial Significance of the Temperature and Potential Window on the Stability of Carbon Supported Pt-alloy Nanoparticles as Oxygen Reduction Reaction Electrocatalysts

10.33774/chemrxiv-2021-sp3fs ◽

2021 ◽

Author(s):

Tina Đukić ◽

Leonard Jean Moriau ◽

Luka Pavko ◽

Mitja Kostelec ◽

Martin Prokop ◽

...

Keyword(s):

Noble Metal ◽

Inductively Coupled Plasma ◽

Reduction Reaction ◽

Critical Parameters ◽

Metal Dissolution ◽

Carbon Corrosion ◽

Inductively Coupled ◽

Pt Alloy ◽

Voltage Potential ◽

The Stability

The present research provides a comprehensive study of carbon-supported intermetallic Pt-alloy electrocatalysts and assesses their stability against metal dissolution in relation to the operating temperature and the potential window using two advanced electrochemical methodologies: (i) the in-house designed high-temperature disk electrode (HT-DE) methodology as well as (ii) a modification of the electrochemical flow cell coupled to an inductively coupled plasma mass spectrometer (EFC-ICP-MS), allowing for highly sensitive time- and potential-resolved measurements of metal dissolution. The findings contradict the generally accepted hypothesis that in contrast to the rate of carbon corrosion, which follows the Arrhenius law and increases exponentially with temperature, the kinetics of Pt and subsequently the less noble metal dissolution are supposed to be for the most part unaffected by temperature. On the contrary, clear evidence is presented that in addition to the importance of the voltage/potential window, the temperature is one of the most critical parameters governing the stability of Pt and thus, in the case of Pt-alloy electrocatalysts also the ability of the nanoparticles (NPs) to retain the less noble metal. Lastly, but also very importantly, results indicate that the rate of Pt redeposition significantly increases with temperature, which has been the main reason why mechanistic interpretation of the temperature-dependent kinetics related to the stability of Pt remained highly speculative until now.

Download Full-text

Effect of Ion Corrosion on 517 Phase Stability

Materials ◽

10.3390/ma13245659 ◽

2020 ◽

Vol 13 (24) ◽

pp. 5659

Author(s):

Guijia Wang ◽

Zhiqi Hu ◽

Jun Chang ◽

Yan Guan ◽

Tingting Zhang ◽

...

Keyword(s):

Compressive Strength ◽

Inductively Coupled Plasma ◽

Rietveld Method ◽

Hydration Product ◽

X Ray Diffraction ◽

Chloride Solutions ◽

Inductively Coupled ◽

Magnesium Oxysulfate ◽

The Stability ◽

Cacl2 Solution

The main hydration product and source of strength of magnesium oxysulfate cement is 5Mg(OH)2·MgSO4·7H2O (known as the 517 phase). Hardened pastes containing 92.38% of the 517 phase were synthesized in this study, and the influence of different types of chloride solutions on the stability and compressive strength of the 517 phase was investigated. X-ray diffraction and the Rietveld method were used to investigate the 517 phase transition in chloride solutions. Ion chromatography and inductively coupled plasma spectrometry were used to analyze the ion concentrations of the chloride solutions. Scanning electron microscopy and mercury injection porosimetry were used to investigate the effect of ion erosion on the microstructure and pore size distribution. The results showed that the crystal structure of 517 phase remained stable upon immersion in chloride solutions (except for the CaCl2 solution) up to 28 days, and there was no discernible attenuation in the compressive strength of the hardened pastes. Immersion of the 517 phase in CaCl2 solution for 28 days caused Ca2+ ions to combine with SO42− groups to generate CaSO4·2H2O, thereby decomposing the 517 phase. An increase in the concentration of magnesium and sulfate ions in the immersion solutions confirmed the decomposition of the 517 phase. Gel-like Mg(OH)2 was observed in the microstructure of the decomposed 517 phase, and the decomposition of the 517 phase increased the porosity of the hardened pastes.

Download Full-text