H2 production: Formulation of catalysts promoting the decomposition of carbon-free hydrogen carriers

In recent years, climate change triggered by carbon dioxide (CO2) emissions has sparked the intense concern of the entire human society. Dependable and economic hydrogen energy technology is significant to achieve the net-zero emission goal. Nitrogen-based fuels offer high hydrogen capacities and safety as a chemical hydrogen storage medium, which is expected to solve the problem of hydrogen storage and transportation. The effective nitrogen-based fuels’ reforming needs high-performance and affordable catalysts, and they are critical for clean and efficient utilization. This work mainly presents computational studies of transition metals, defective and doped graphene, and single-atom catalysts in terms of their electronic structures and catalytic performances. In chapter 3, the catalytic decomposition of hydrazine, the poisoning oxidation of Ir catalyst was identified and the hydrazine decomposition mechanism leading to NH3 and H2 was understood. Carbon defects and doped materials as non-metal catalysts were studied to catalyze NH3 reforming; the reaction mechanisms were resolved as a function of the defect type in chapter 4. In chapter 5, transition metal catalysts with typical catalytic performance were selected, and DFT calculations and micro-kinetic models were employed to track the surface species and product composition during the reaction process, revealing the internal relationship between the surface species, catalytic activity, and reaction conditions. Based on the above work, single-atom transition metal catalysts with specific structures were modeled, and DFT calculations and micro-kinetic models were applied to study the catalytic performance of NH3 reforming in chapter 6. And the efficient and stable single-atom catalysts are explored to improve metal atom utilization efficiency and reduce catalyst cost. This work aims at improving the understanding of the structure and catalytic behaviors of these materials and exploring their applications in hydrogen energy, which contributes to the construction of a net-zero global society