Hydrogen production by ammonia decomposition: A strategy to enhance the activity and stability of metal catalysts

Hydrogen, as an emerging clean energy source, confronts various technical challenges in storage and transportation, notably high costs and operational complexity. With a hydrogen content of up to 17.6 wt%, ammonia is recognized as an exceptionally promising hydrogen storage medium. Its decomposition produces only nitrogen and hydrogen, and its ease of liquefaction at room temperature greatly enhances the ease of storage and transportation. To achieve large-scale ammonia decomposition for hydrogen production, there is an urgent requirement to develop catalysts that are highly active and stable. Although ruthenium-based catalysts currently demonstrate the greatest catalytic activity, their high cost and limited availability impede their widespread commercial application. To tackle this issue, researchers have been dedicated to developing non-precious metal catalysts and synthetic metallic catalysts that are based on more sustainable practices. Nickel and cobalt-based catalysts, in particular, have garnered significant interest due to their relatively lower costs. The current research is focused on enhancing the performance of non-precious metal catalysts by refining their preparation methods and optimizing reaction conditions. In this paper, we outline the fundamental principles of catalytic ammonia decomposition and provide a comprehensive review of the latest advancements in various types of catalysts, with a detailed summary of the findings related to non-precious metal catalysts. It analyzes the performance strengths and limitations of various types of catalysts and offers insights into future research directions.