Search research articles

ABOUT JoVE

Overview Leadership Blog JoVE Help Center

AUTHORS

Publishing Process Editorial Board Scope & Policies Peer Review FAQ Submit

LIBRARIANS

Testimonials Subscriptions Access Resources Library Advisory Board FAQ

RESEARCH

JoVE Journal Methods Collections JoVE Encyclopedia of Experiments Archive

EDUCATION

JoVE Core JoVE Business JoVE Science Education JoVE Lab Manual Faculty Resource Center Faculty Site

Terms & Conditions of Use

Related Concept Videos

Oxidation Numbers

Oxidation Numbers

In redox reactions, the transfer of electrons occurs between reacting species. Electron transfer is described by a hypothetical number called the oxidation number (or oxidation state). It represents the effective charge of an atom or element, which is assigned using a set of rules.

Bonding in Metals

Bonding in Metals

Metallic bonds are formed between two metal atoms. A simplified model to describe metallic bonding has been developed by Paul Drüde called the “Electron Sea Model”.

Oxidation-Reduction Reactions

Oxidation-Reduction Reactions

Oxidation–Reduction Reactions

Ionic Bonding and Electron Transfer

Ionic Bonding and Electron Transfer

Ions are atoms or molecules bearing an electrical charge. A cation (a positive ion) forms when a neutral atom loses one or more electrons from its valence shell, and an anion (a negative ion) forms when a neutral atom gains one or more electrons in its valence shell. Compounds composed of ions are called ionic compounds (or salts), and their constituent ions are held together by ionic bonds: electrostatic forces of attraction between oppositely charged cations and anions.

Redox Reactions

Redox Reactions

Redox reactions are vital biochemical processes that underpin energy metabolism in cells. These reactions involve the transfer of electrons between molecules, occurring in tandem as oxidation and reduction. Oxidation refers to the loss of electrons, while reduction denotes their gain. This coupling ensures the seamless flow of electrons through metabolic pathways. For example, in bacterial metabolism, glucose undergoes oxidation to carbon dioxide, while oxygen is simultaneously reduced to...

Redox Reactions

Redox Reactions

Oxidation-reduction or redox reactions involve the transfer of electrons from one molecule or atom to another. When an atom gains an electron, another atom must lose an electron, meaning oxidation and reduction must occur together. Since the redox occurs in pairs, the atom that gets oxidized is also called the reducing agent or reductant, and the atom that is reduced is also called the oxidizing agent or oxidant. A straightforward way to remember the definitions of oxidation and reduction is...

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by

Same author

Does set configuration influence long-term adaptations to complex training in national-level wrestlers? A volume-matched randomized trial.

PeerJ·2026

Same author

Forecasting monthly hepatitis B cases in China: a nationwide comparative study based on surveillance data.

BMC public health·2026

Same author

Effects of ischemic preconditioning on lower-limb anaerobic performance and neuromuscular adaptations.

PeerJ·2026

Same author

Protocol for identifying recirculating thymic regulatory T cells and characterizing the role of Eos in their function using scRNA-seq and TCR-seq.

STAR protocols·2026

Same author

Prolactin acts on proopiomelanocortin neurons to regulate hepatic lipid metabolism.

Hepatology international·2026

Same author

A hydrogen-bonded zwitterionic hydrogel electrolyte constructs freeze-resistant and flame-retardant flexible zinc-ion capacitors.

Nanoscale·2026

Search research articles

Related Experiment Video

Updated: Jun 12, 2026

Protein Film Infrared Electrochemistry Demonstrated for Study of H2 Oxidation by a [NiFe] Hydrogenase

Protein Film Infrared Electrochemistry Demonstrated for Study of H₂ Oxidation by a [NiFe] Hydrogenase

Published on: December 4, 2017

Calcium-Mediated Fe─N Bond Reinforcement for Ultra-Stable Oxygen Reduction Reaction.

Xuan Xie¹, Quanyu Wen¹, Zhuang Wu²

¹Key Laboratory of Polymer Materials of Gansu Province, Analytical Testing Center, College of Chemistry and Chemical Engineering, Key Laboratory of Eco-functional Polymer Materials of the Ministry of Education, College of Engineering, Northwest Normal University, Lanzhou, P. R. China.

Advanced Materials (Deerfield Beach, Fla.)

|June 11, 2026

Summary

Researchers developed a new iron-calcium catalyst (Fe-Ca) that significantly improves the durability of oxygen reduction reactions (ORR) and enhances zinc-air battery performance.

Keywords:

Zn‐Air batteries alkaline earth metal elements dual‐atom sites electrocatalysis durability oxygen reduction reaction

More Related Videos

Anaerobic Protein Purification and Kinetic Analysis via Oxygen Electrode for Studying DesB Dioxygenase Activity and Inhibition

Anaerobic Protein Purification and Kinetic Analysis via Oxygen Electrode for Studying DesB Dioxygenase Activity and Inhibition

Published on: October 3, 2018

Synthesis and Evaluation of a Ruthenium-based Mitochondrial Calcium Uptake Inhibitor

Synthesis and Evaluation of a Ruthenium-based Mitochondrial Calcium Uptake Inhibitor

Published on: October 26, 2017

Related Experiment Videos

Last Updated: Jun 12, 2026

Protein Film Infrared Electrochemistry Demonstrated for Study of H2 Oxidation by a [NiFe] Hydrogenase

Protein Film Infrared Electrochemistry Demonstrated for Study of H₂ Oxidation by a [NiFe] Hydrogenase

Published on: December 4, 2017

Anaerobic Protein Purification and Kinetic Analysis via Oxygen Electrode for Studying DesB Dioxygenase Activity and Inhibition

Anaerobic Protein Purification and Kinetic Analysis via Oxygen Electrode for Studying DesB Dioxygenase Activity and Inhibition

Published on: October 3, 2018

Synthesis and Evaluation of a Ruthenium-based Mitochondrial Calcium Uptake Inhibitor

Synthesis and Evaluation of a Ruthenium-based Mitochondrial Calcium Uptake Inhibitor

Published on: October 26, 2017

Area of Science:

Materials Science
Electrochemistry
Catalysis

Background:

Atomically dispersed Fe-N-C catalysts are crucial for oxygen reduction reactions (ORR).
Electrochemical leaching of iron (Fe) active sites limits the practical application of these catalysts.
Stabilizing metalloenzyme active sites with calcium (Ca2+) inspired a new catalyst design.

Purpose of the Study:

To design a novel Fe-Ca dual-atom sites catalyst (Ca/Fe-N-C) to overcome Fe leaching issues.
To investigate the role of Ca as an electronic modulator and structural stabilizer for Fe active sites.
To evaluate the performance and durability of the Ca/Fe-N-C catalyst in ORR and zinc-air batteries (ZABs).

Main Methods:

Synthesis of Ca/Fe-N-C catalyst on amorphous porous carbon nanosheets.
Electrochemical characterization of the catalyst for ORR performance (half-wave potential).
Durability testing of the catalyst over extended cycles and in ZABs.

Main Results:

The Ca/Fe-N-C catalyst exhibited a high half-wave potential of 0.912 V in alkaline media.
Exceptional durability was observed, with negligible decay after 80,000 cycles.
Ca/Fe-N-C based cathodes in ZABs achieved a peak power density of 215 mW cm-2 and operated for over 1110 hours.

Conclusions:

Calcium acts as an effective electronic modulator and structural stabilizer for Fe active sites, enhancing ORR performance and durability.
The study establishes a general strategy for designing robust atomically dispersed catalysts using alkaline-earth metals.
The developed Ca/Fe-N-C catalyst offers superior performance compared to benchmark Pt/C for energy conversion devices like ZABs.