Determination of the bulk cobalt valence state of co-perovskites containing surface-adsorbed impurities.

Anal Chem

General Energy Research, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland.

Published: October 2006

We used thermogravimetric hydrogen reduction and iodometric titration to determine the bulk valence state of cobalt in Co-perovskites containing surface carbonate hydroxide or hydroxyl groups. It could be shown that thermogravimetric hydrogen reduction experiments are very sensitive to volatile surface groups, but due to their volatility, they can be specified and the bulk valence state of cobalt can still be deduced from these experiments. The iodometric titration is less sensitive to small volatile surface impurities, but precaution has to be taken that oxygen or iodine does not escape from the solution during dissolution of the sample. Best results were obtained if the sample was titrated during dissolution in a closed argon floated titration apparatus. We tested the two methods using LaCoO3 perovskite as a sample with a known valence state. Both methods delivered satisfactory results, and the valence state could be determined with an accuracy of better than 1%.

Download full-text PDF

Source
http://dx.doi.org/10.1021/ac060903wDOI Listing

Publication Analysis

Top Keywords

valence state
20
thermogravimetric hydrogen
8
hydrogen reduction
8
iodometric titration
8
bulk valence
8
state cobalt
8
volatile surface
8
valence
5
state
5
determination bulk
4

Similar Publications

NbO(OH) has emerged as a highly attractive photocatalyst based on its chemical stability, energetic band positions, and large active lattice sites. Compared to other various photocatalytic semiconductors, it can be synthesized easily. This study presents a systematic analysis of pristine and doped NbO(OH) based on recent developments in related research.

View Article and Find Full Text PDF

Background: Positive alcohol expectancies are linked to increased alcohol use among college students. Difficulties regulating emotion have been shown to moderate this relationship, though little research accounts for differences based on the valence of the emotion being regulated.

Objective: To examine the independent moderating roles of positive and negative emotion dysregulation on the association between positive alcohol expectancies and alcohol use.

View Article and Find Full Text PDF

Emotional experiences involve dynamic multisensory perception, yet most EEG research uses unimodal stimuli such as naturalistic scene photographs. Recent research suggests that realistic emotional videos reliably reduce the amplitude of a steady-state visual evoked potential (ssVEP) elicited by a flickering border. Here, we examine the extent to which this video-ssVEP measure compares with the well-established Late Positive Potential (LPP) that is reliably larger for emotional relative to neutral scenes.

View Article and Find Full Text PDF

Electrochemical oxidation of small molecules shows great promise to substitute oxygen evolution reaction (OER) or hydrogen oxidation reaction (HOR) to enhance reaction kinetics and reduce energy consumption, as well as produce high-valued chemicals or serve as fuels. For these oxidation reactions, high-valence metal sites generated at oxidative potentials are typically considered as active sites to trigger the oxidation process of small molecules. Isolated atom site catalysts (IASCs) have been developed as an ideal system to precisely regulate the oxidation state and coordination environment of single-metal centers, and thus optimize their catalytic property.

View Article and Find Full Text PDF

Background: Interstitial cystitis/bladder pain syndrome (IC/BPS) is a multifactorial, chronic syndrome involving urinary frequency, urgency, and bladder discomfort. These IC/BPS symptoms can significantly impact individuals' quality of life, affecting their mental, physical, sexual, and financial well-being. Individuals sometimes rely on peer-to-peer support to understand the disease and find methods of alleviating symptoms.

View Article and Find Full Text PDF

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!