Enhanced Catalytic Performance of N-Doped Carbon Sphere-Supported Pd Nanoparticles by Secondary Nitrogen Source Regulation for Formic Acid Dehydrogenation

Abstract

The development of catalysts with high selectivity, good catalytic activity, and excellent cycle performance is of significance for the application of formic acid (HCOOH, FA) as a hydrogen support. Herein, Pd is deposited on a series of N-doped carbons, which are prepared by cocarbonization of Ncontaining zeolite imidazole frameworks (ZIF-8) and other N/C sources (melamine, xylitol, urea, and glucose), for hydrogen generation from FA. The results demonstrate that the introduction of a secondary N/C source further affects the catalytic performance of Pd by adjusting the morphology, specific surface area, N content, and type of carbon. The effects of N atoms and the favorable reaction pathways of FA dehydrogenation were revealed by theoretical calculation. This work will improve the understanding of N doping on the decomposition mechanism of FA and provide a new approach for the rational design of metal-N-C materials.

“On–off” switch for H2 and O2 generation from HCOOH resp. H2O2

“…In addition, the catalytic performance of the Pd/CNS‐800 nanocatalyst has also been compared with recent reports for selective H 2 generation from FA dehydrogenation 49,73,80–92 . Figure 10 shows that the catalytic activity of Pd/CNS‐800 nanocatalyst is fairly acceptable, with the TOF of 2478 h −1 .…”

“…Then, XPS of Pd/C has also been measured for comparison with Pd/CNS‐800. As shown in Figure , there is a slight shift in the Pd 3d of Pd/CNS‐800 as compared to that of Pd/C, indicating that charge transfer from N sites to Pd occurs via orbital hybridization between N and Pd 71–73 . It appears that graphitic C or N in CNS‐800 is serving as an electron donor to the Pd atom and increases its surface electron density, facilitating the cleavage of the C–H bond upon FA dehydrogenation.…”

“…As shown in Figure S14, there is a slight shift in the Pd 3d of Pd/CNS-800 as compared to that of Pd/C, indicating that charge transfer from N sites to Pd occurs via orbital hybridization between N and Pd. [71][72][73] It appears that graphitic C or N in CNS-800 is serving as an electron donor to the Pd atom and increases its surface electron density, facilitating the cleavage of the C-H bond upon FA dehydrogenation. To test the selectivity of H 2 production upon the FA dehydrogenation, the gas mixture (H 2 and CO 2 ) released from HCOOH dehydrogenation flowed into an NaOH solution for the selective absorption and removal of CO 2 .…”

“…[77][78][79] In addition, the catalytic performance of the Pd/CNS-800 nanocatalyst has also been compared with recent reports for selective H 2 generation from FA dehydrogenation. 49,73,[80][81][82][83][84][85][86][87][88][89][90][91][92] gratefully acknowledged; thanks to eceshi (www.eceshi. com) for the transmission electron microscope test and Yuan Zhou from Shiyanjia Lab (www.shiyanjia.com) for the gas chromatogram analysis.…”

Hydrogen Production via Cerium-Promoted Dehydrogenation of Formic Acid Catalyzed by Carbon-Supported Palladium Nanoparticles

“…As palladium (Pd) is the most active metal for aqueous formic acid dehydrogenation, Pd-based catalysts have been extensively used. Pd alloyed with Ag, Au, Cu, Co, or Ni showed considerably improved activity compared to monometallic Pd catalysts. ,− Adopting novel supports or modifying supports with dopants such as nitrogen, amine-functional groups, and metal oxide also was used in a way to enhance the activity of Pd-based catalysts. − ,− These enhanced catalytic activities were attributed to the particle size of active metals, ligand effect (electronic modification), strain effect (changes in lattice distance), and interaction of dopants with reactants or intermediates, and in most cases, a combination of these effects. Despite the considerable improvement in catalytic activity, ironically, such combined effects make it difficult to understand the independent role of each factor in the formic acid dehydrogenation reaction.…”