Fine-tuning Ru nanocatalyst size in UiO-66-NH2-derived carbon nitride for efficient hydrogen production from ammonia borane

Ammonia borane (AB) is a highly promising hydrogen carrier with significant potential for safe and efficient hydrogen storage and transportation. However, its high chemical stability poses considerable challenges for hydrogen release, emphasizing the importance of highly efficient catalysts. In this study, we present Ru nanocatalysts supported on UiO-66-NH 2 -derived carbon nitride (Ru/CN) as high-performance catalysts for AB hydrolysis. A facile pyrolysis-impregnation method was employed to synthesize highly dispersed Ru nanoparticles with tunable sizes, while retaining the octahedral morphology of the MOF-derived support. Detailed characterizations revealed tunable Ru nanoparticle sizes achieved by simply adjusting the Ru loading. Among the catalysts, the 2.5Ru/CN, featuring Ru nanoparticles with an average size of 2.2 nm, achieved an impressive turnover frequency of 493 mol H 2 (mol Ru −1 ·min −1 ) at 30 °C, demonstrating exceptional catalytic activity. Density functional theory (DFT) calculations confirmed that the optimized Ru cluster size enhances key catalytic steps, including H 2 O dissociation, AB activation, and H 2 desorption. This study highlights the critical role of fine-tuning nanoparticle sizes and provides valuable insights into the rational design of advanced catalysts for more efficient hydrogen production.