Issue 31, 2017

Tailoring the framework composition of carbon nitride to improve the catalytic efficiency of the stabilised palladium atoms

Abstract

Graphitic carbon nitride (g-C3N4) exhibits unique properties for the preparation of single-atom heterogeneous catalysts (SAHCs) due to the presence of sixfold nitrogen-based coordination sites in the lattice. Despite the potential to profoundly affect the metal stabilisation and resulting catalytic properties, no work has previously investigated the effect of modifying the carrier composition. Here, we study the impact of doping carbon in g-C3N4 on the interaction with palladium. This is achieved by introducing carbon-rich heterocycles (barbituric acid or 2,4,6-triaminopyrimidine) during the synthesis of bulk and mesoporous g-C3N4. Palladium is subsequently introduced via microwave-irradiation-assisted deposition, which emerges as a highly effective route for the dispersion of single atoms. Detailed characterisation confirms the controlled variation of the C/N ratio of the lattice and reveals the complex interplay with the crystal size, surface area, amount of defects, basic properties and thermal stability of the carrier. Atomic dispersions of palladium with similar surface densities could be obtained on both the stoichiometric and carbon-doped carriers in mesoporous form, but appreciable differences are observed in the ratio of Pd2+/Pd4+. The latter, which provides a measure of the degree of electron transfer from the metal to the carrier, is found to correlate with the activity in the continuous flow semi-hydrogenation of 2-methyl-3-butyn-2-ol. Density functional theory calculations support the decreased adsorption energy of palladium upon doping with carbon and reveal the potentially significant impact of oxygen-containing defects. The findings demonstrate the importance of understanding the metal-carrier interaction to optimise the catalytic efficiency of SAHCs.

Graphical abstract: Tailoring the framework composition of carbon nitride to improve the catalytic efficiency of the stabilised palladium atoms

Supplementary files

Article information

Article type
Paper
Submitted
26 मई 2017
Accepted
12 जून 2017
First published
12 जून 2017

J. Mater. Chem. A, 2017,5, 16393-16403

Tailoring the framework composition of carbon nitride to improve the catalytic efficiency of the stabilised palladium atoms

E. Vorobyeva, Z. Chen, S. Mitchell, R. K. Leary, P. Midgley, J. M. Thomas, R. Hauert, E. Fako, N. López and J. Pérez-Ramírez, J. Mater. Chem. A, 2017, 5, 16393 DOI: 10.1039/C7TA04607C

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements