Liquid organic hydrogen carriers (LOHCs): Recent advancements and development in hydrogen storage technology

The global transition to low-carbon energy has positioned hydrogen as a key energy vector, yet safe and efficient storage remains a critical challenge. Liquid Organic Hydrogen Carriers (LOHCs) offer a promising solution, enabling reversible hydrogen storage with gravimetric capacities of 6-8 wt% and volumetric densities up to 70 kg H 2 m −3 . This review examines four principal LOHC families: carbocyclic, heterocyclic, alcohol-based, and formic acid systems. Carbocyclic LOHCs demonstrate high maturity (>95% conversion, >99% selectivity, >10,000-h catalyst lifetimes) but require elevated dehydrogenation temperatures (270-350 °C). Heterocyclic systems such as N-ethylcarbazole operate at lower temperatures (170-270 °C) with >99.99% hydrogen purity. Alcohol-based systems offer high hydrogen content (12.5 wt% for methanol) under mild conditions, though CO generation remains a limitation. Advances in bimetallic, single-atom, and metal–support catalysts have improved performance across all systems. Key challenges, including catalyst deactivation, high energy demands, and low round-trip efficiency, necessitate future focus on low-temperature catalysis, non-noble metal catalysts, and integrated reactor designs.