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Catalysis

Catalysis

The presence of a catalyst affects the rate of a chemical reaction. A catalyst is a substance that can increase the reaction rate without being consumed during the process. A basic comprehension of a catalysts’ role during chemical reactions can be understood from the concept of reaction mechanisms and energy diagrams.

Reduction of Alkenes: Catalytic Hydrogenation

Reduction of Alkenes: Catalytic Hydrogenation

Alkenes undergo reduction by the addition of molecular hydrogen to give alkanes. Because the process generally occurs in the presence of a transition-metal catalyst, the reaction is called catalytic hydrogenation.
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the...

Reduction of Alkenes: Asymmetric Catalytic Hydrogenation

Reduction of Alkenes: Asymmetric Catalytic Hydrogenation

Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...

Reduction of Benzene to Cyclohexane: Catalytic Hydrogenation

Reduction of Benzene to Cyclohexane: Catalytic Hydrogenation

Unlike the easy catalytic hydrogenation of an alkene double bond, hydrogenation of a benzene double bond under similar reaction conditions does not take place easily. For example, in the reduction of stilbene, the benzene ring remains unaffected while the alkene bond gets reduced. Hydrogenation of an alkene double bond is exothermic and a favorable process. In contrast, to hydrogenate the first unsaturated bond of benzene, an energy input is needed; that is, the process is endothermic. This is...

Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation

Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation

Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.

Hydrogen Bonds

Hydrogen Bonds

Hydrogen bonds are weak attractions between atoms that have formed other chemical bonds. One of these atoms is electronegative, like oxygen, and has a partial negative charge. The other is a hydrogen atom that has bonded with another electronegative atom and has a partial positive charge.
Hydrogen Bonds Control the World!
Because hydrogen has very weak electronegativity when it binds with a strongly electronegative atom, such as oxygen or nitrogen, electrons in the bond are unequally shared....

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Updated: Jan 8, 2026

Multiscale Sampling of a Heterogeneous Water/Metal Catalyst Interface using Density Functional Theory and Force-Field Molecular Dynamics

Multiscale Sampling of a Heterogeneous Water/Metal Catalyst Interface using Density Functional Theory and Force-Field Molecular Dynamics

Published on: April 12, 2019

Molecular Catalysts for the Hydrogen Evolution Reaction: A First-Principles Study.

Samuel Lemay¹, Félix Paradis¹, Mihaela Cibian¹

¹Institut de Recherche Sur l'hydrogène, Université du Québec à Trois-Rivières, Trois-Rivières, C.P. 500 G8z 4m3, Canada.

|December 22, 2025

Summary

This summary is machine-generated.

Molecular catalysts, like nickel and copper systems, show promise for the hydrogen evolution reaction (HER). These earth-abundant catalysts offer efficient pathways for producing hydrogen fuel via electrolysis and photocatalysis.

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A Simple, Low-cost, and Robust System to Measure the Volume of Hydrogen Evolved by Chemical Reactions with Aqueous Solutions

A Simple, Low-cost, and Robust System to Measure the Volume of Hydrogen Evolved by Chemical Reactions with Aqueous Solutions

Published on: August 17, 2016

Area of Science:

Materials Science
Computational Chemistry
Electrochemistry

Background:

Molecular catalysts are crucial for efficient hydrogen evolution reaction (HER) via electrolysis and photocatalysis.
Developing cost-effective and earth-abundant catalysts is a key challenge in sustainable energy research.

Purpose of the Study:

To investigate the hydrogen evolution reaction (HER) mechanism using first-principles calculations for four molecular catalysts.
To identify optimal protonation sites and catalytic pathways for enhanced HER efficiency.
To compare the performance of cobalt, nickel, and copper-based catalysts under various operating conditions.

Main Methods:

Utilizing density functional theory (DFT) to compute Gibbs free energy changes at each step of the HER.
Analyzing potential-pH diagrams to determine spontaneous HER operating conditions.
Evaluating catalyst efficiency based on energetic span and reaction pathways.

Main Results:

Identified favorable catalytic pathways and protonation sites for Co-(bpy)2, Co-(PyDAT)2, Ni-(PyDAT)2, and Cu-(PyDAT)2.
Determined optimal operating conditions for spontaneous HER using potential-pH diagrams.
Demonstrated that nickel- and copper-based catalysts are viable, precious-metal-free alternatives for HER.

Conclusions:

Nickel- and copper-based molecular catalysts present promising, sustainable alternatives for the hydrogen evolution reaction.
Computational methods like DFT are effective in predicting and optimizing molecular catalyst performance.
Understanding reaction mechanisms and operating conditions is vital for designing efficient HER catalysts.