Enhancing activity, selectivity and stability of palladium catalysts in formic acid decomposition: Effect of support functionalization

Synthesis of Pd/Carbon Hollow Spheres by the Microwave Discharge Method for Catalytic Debenzylation

Pd/C catalysts have been widely applied in the debenzylation process due to their excellent ability of hydrogenolysis. However, they have been suffering from the problems of agglomeration and loss of active components, which lead to decreased and unstable activity. Thus, it is still a challenge to achieve Pd/C catalysts with high activity and stability. Herein, we propose a strategy for preparing Pd/C catalysts on porous carbon hollow spheres by a microwave discharge method. Due to the high-temperature property and reducibility of microwave discharge, Pd precursors can be rapidly reduced, resulting in well-dispersed Pd nanoparticles with a small size on the carbon carrier. Besides, the matched mesopores in the carbon hollow spheres can anchor Pd nanoparticles and effectively reduce the agglomeration and loss of Pd nanoparticles during the catalytic reaction. As a result, the as-prepared Pd/mesoporous carbon hollow spheres exhibit high and stable activity in the debenzylation reaction.

Enhanced stability of sub-nanometric iridium decorated graphitic carbon nitride for H2 production upon hydrous hydrazine decomposition

Stabilizing metal nanoparticles is vital for large scale implementations of supported metal catalysts, particularly for a sustainable transition to clean energy, e.g., H₂ production. In this work, iridium sub-nanometric particles were deposited on commercial graphite and on graphitic carbon nitride by a wet impregnation method to investigate the metal-support interaction during the hydrous hydrazine decomposition reaction. To establish a structure-activity relationship, samples were characterized by transmission electron microscopy and X-ray photoelectron spectroscopy. The catalytic performance of the synthesized materials was evaluated under mild reaction conditions, i.e. 323 K and ambient pressure. The results showed that graphitic carbon nitride (GCN) enhances the stability of Ir nanoparticles compared to graphite, while maintaining remarkable activity and selectivity. Simulation techniques including Genetic Algorithm geometry screening and electronic structure analyses were employed to provide a valuable atomic level understanding of the metal-support interactions. N anchoring sites of GCN were found to minimise the thermodynamic driving force of coalescence, thus improving the catalyst stability, as well as to lead charge redistributions in the cluster improving the resistance to poisoning by decomposition intermediates.