Homogeneous vs. heterogeneous catalysis for hydrogen evolution by a nickel(ii) bis(diphosphine) complex
Giovanni Bergamini1, Mirco Natali
1Department of Chemical and Pharmaceutical Sciences, University of Ferrara, Via L. Borsari 46, 44121, Ferrara, Italy. mirco.natali@unife.it.
Abstract:
Nickel(ii) bis(diphosphine) complex 1 bearing carboxylic acid functional groups at the periphery has been prepared and characterized. Its catalytic ability towards the hydrogen evolution reaction (HER) has been evaluated under different experimental conditions: (i) under homogeneous electrocatalysis in acetonitrile using trifluoroacetic acid as the proton source, (ii) under homogeneous photocatalysis in aqueous solution using Ru(bpy)32+ (where bpy = 2,2'-bipyridine) as the sensitizer and ascorbic acid as the sacrificial electron donor, and (iii) under heterogeneous electrochemical conditions upon grafting onto mesoporous TiO2. The results show that complex 1 is a competent and efficient catalyst for the HER under both homogeneous electro- and photochemical conditions, while undergoes rapid deactivation once attached onto the TiO2 surface. This is attributed to both catalyst binding mode and structural rigidity imparted by covalent grafting, which highlights how catalyst design has to be considered for the direct transposition of molecular catalysis on (photo)electrode surfaces.
More Related Videos
10:19Synthesis and Testing of Supported Pt-Cu Solid Solution Nanoparticle Catalysts for Propane Dehydrogenation
Published on: July 18, 2017
11:44Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-phosphinetriyltripiperidine]}palladium Under Mild Reaction Conditions
Published on: March 20, 2014
Related Concept Videos
Catalysis
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
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 Alkenes: 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 Alkynes to cis-Alkenes: Catalytic Hydrogenation
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.
Reduction of Benzene to Cyclohexane: Catalytic Hydrogenation
Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
