Highly Dispersed Pd-CeO_x Nanoparticles in Zeolite Nanosheets for Efficient CO₂-Mediated Hydrogen Storage and Release

Formic acid (FA) dehydrogenation and CO₂ hydrogenation to FA/formate represent promising methodologies for the efficient and clean storage and release of hydrogen, forming a CO₂-neutral energy cycle. Here, we report the synthesis of highly dispersed and stable bimetallic Pd-based nanoparticles, immobilized on self-pillared silicalite-1 (SP-S-1) zeolite nanosheets using an incipient wetness co-impregnation technique. Owing to the highly accessible active sites, effective mass transfer, exceptional hydrophilicity, and the synergistic effect of the bimetallic species, the optimized PdCe_0.2/SP-S-1 catalyst demonstrated unparalleled catalytic performance in both FA dehydrogenation and CO₂ hydrogenation to formate. Remarkably, it achieved a hydrogen generation rate of 5974 mol_H2 mol_Pd⁻¹ h⁻¹ and a formate production rate of 536 mol_formate mol_Pd⁻¹ h⁻¹ at 50 °C, surpassing most previously reported heterogeneous catalysts under similar conditions. Density functional theory calculations reveal that the interfacial effect between Pd and cerium oxide clusters substantially reduces the activation barriers for both reactions, thereby increasing the catalytic performance. Our research not only showcases a compelling application of zeolite nanosheet-supported bimetallic nanocatalysts in CO₂-mediated hydrogen storage and release but also contributes valuable insights towards the development of safe, efficient, and sustainable hydrogen technologies.