The role of phosphorus in catalytic processes of hydrogen energy technology: a perspective.

The pursuit of hydrogen energy presents a promising path toward meeting growing energy needs sustainably while addressing urgent climate issues. However, developing a hydrogen economy demands significant investments in advanced infrastructure for production, storage, and transportation. The use of critical minerals is essential at nearly every stage of hydrogen technology to ensure efficiency. Consequently, one of the key future challenges will be managing these minerals responsibly to prevent depletion. Phosphorus, for instance, plays a crucial role in research on liquid organic hydrogen storage systems and is becoming increasingly important in catalyst development for water splitting. As research in this field expands rapidly, the demand for phosphorus in hydrogen technology will inevitably rise. This review highlights phosphorus' significance in advancing hydrogen technology, covering its applications in heterogeneous photocatalysis, including black phosphorus, red phosphorus, transition metal phosphides, and emerging high-entropy phosphide materials, as well as phosphorus-doped supports for ammonia borane hydrolysis. In homogeneous catalysis, the review examines the role of phosphorus-based ligands in designing catalysts for liquid organic hydrogen carrier (LOHC) systems, particularly those involving carbon dioxide conversion into formic acid, formate, amides, and methanol. The review also addresses catalyst deactivation mechanisms, theoretical descriptors for rational catalyst design, and sustainable phosphorus management strategies including immobilization, durability, recovery, and efficiency metrics. By emphasizing phosphorus' vital contributions, this article aims to raise awareness of its role in the hydrogen economy, encourage its thoughtful integration into future technologies, and promote sustainable practices in its use.