Elucidating Interaction between Palladium and N-Doped Carbon Nanotubes: Effect of Electronic Property on Activity for Nitrobenzene Hydrogenation

Abstract

Nitrogen dopants of carbon materials remarkably improve the stability and tune the catalytic performance of supported metal nanoparticles. However, it is still controversial how the Pd−N metal−support-interaction (MSI) influences the catalysis. Herein, the density function theory (DFT) calculations and X-ray photoelectron spectroscopy (XPS) were combined to rationalize the Pd−N MSI. DFT calculations suggested that Pd adsorbs on N-doped carbon nanotubes (N@CNTs) and donates electrons to pyridinic nitrogen. It was further experimentally proved using XPS through a titration method by gradually increasing Pd content or changing the N content of support by a postheat-treatment. The Pd catalysts display electron-deficiency depending on the intensity of MSI between Pd and pyridinic nitrogen, measured by Pd 3d binding energy. It paves the way to the rational synthesis of Pd catalysts with a tunable electronic state for the targeted catalytic reaction. Using the hydrogenation of nitrobenzene as the probe reaction, it was revealed that the reaction activity can be facilely tuned by the Pd−N MSI, due to the strong adsorption of nitro-groups on electron-deficient Pd nanoparticles.

PdAu alloy nanoparticles supported on nitrogen-doped carbon black as highly active catalysts for Ullmann coupling and nitrophenol hydrogenation reactions

“…56 Compared with the PdAu/CB sample (Fig. S1 †), the Pd and Au peak positions of PdAu/NCB shi to higher binding energies, which is attributed to the metal-support interaction (MSI) between PdAu nanoparticles and NCB, 57 suggesting an enhanced attraction force between the PdAu atoms and the NCB support. 48…”

“…Obviously, N-doping can improve the catalytic performance due to an enhanced attraction force between PdAu atoms and the NCB support. 48,57 We also investigate the effect of temperature on the hydrogenation reaction. Four different temperatures ranging from 20 to 35 C were chosen for the reduction of 2-NP, 3-NP and 4-NP.…”

Designing of Ultrafine PdNPs Immobilized Pyridinic‐NDoped Carbon and Evaluation of its Catalytic Potential for Konevenagel Condensation, Synthesis of 4H‐pyran Derivatives and Nitroreduction

“…It is widely accepted that the nitrogen atoms in metal modified N ‐doping carbon catalysts act as base sites which could increase the performance of various reactions such C−C bond formation, C−O bond formation, reduction, oxidation, C−H activation, etc . Recently, it is observed that the adsorption of Pd on pyridinic‐ N is more favorable than that on graphitic‐ N . Here, we tried to synthesize pyridinic‐ N doped carbon support by keeping low temperature for doping so that only one type i. e .…”

Microenvironment Engineering of Ruthenium Nanoparticles Incorporated into Silica Nanoreactors for Enhanced Hydrogenations

“…[1,2] Previous investigations suggest that amino acid residues around the catalytic active sites of enzymes could assist enriching,organizing, and activating substrates via non-covalent interactions. [4][5][6][7][8] Generally, the catalytic performance of metal NPs can be modulated by modifying its physicochemical properties,s uch as the size, shape,a nd interactions with supports. [4][5][6][7][8] Generally, the catalytic performance of metal NPs can be modulated by modifying its physicochemical properties,s uch as the size, shape,a nd interactions with supports.…”

“…[3] Supported metal nanoparticles are an important class of catalyst materials and they have been widely used in industry for various chemical reactions,s uch as hydrogenation, oxidation, C À Cc oupling,a nd isomerization. [4][5][6][7][8] Generally, the catalytic performance of metal NPs can be modulated by modifying its physicochemical properties,s uch as the size, shape,a nd interactions with supports. [4] Additionally,p revious investigations have showcased the importance of microenvironments in tuning the catalytic performance of metal NPs by affecting its adsorption energy and adsorption modes of substrates, [9][10][11][12][13] which could be realized via the generating as teric hindrance around metal NPs, [14][15][16][17] introducing the binding site with specific functional group near metal NPs, [18][19][20][21] and so on.Thec atalytic hydrogenation of benzoic acid (BA) is of pivotal importance in industry.H owever,n egligible conversion of BA was obtained in aprotic organic solvents under similar conditions (60 8 8C, 1MPa) over metal NPs.…”