State-of-the-Art review of liquid organic hydrogen carriers for hydrogen storage and transport: challenges and perspectives

Despite the difficulty of creating safe and effective hydrogen storage technologies, liquid organic hydrogen carriers (LOHCs) technology offers promise for stable and effective hydrogen storage and transportation, allowing for long-cycle hydrogen storage and safe and affordable large-scale transoceanic transportation. This research is a bibliometric and systematic review regarding research trends from the year 2000 to 2024 on LOHCs. The analysis reveals a significant increase in the output of global scientific literature on the topic, with a growth rate of 38.67 and an average citation rate of 29.69, indicating that the LOHCs have had increasing attention in terms of their possible solutions for hydrogen storage and transportation. The focus areas included hydrogenation/dehydrogenation processes, important studies on the development of efficient carrier molecules (dibenzyl-toluene, N-ethylcarbazole), optimization of catalyst systems (mostly platinum and ruthenium), and confirmation of thermodynamic characterization, thermal integration, and reactor efficiencies in the area. The thematic mapping is indicative of crossovers between molecular innovation and wider system energy strategies. Life cycle analysis and techno-economic assessments showed that LOHC systems today cannot be sustained and are expensive. Future research should therefore focus on quantum chemical simulations, life cycle assessments, and their coupling to green hydrogen integration and hybrid reactor designs. The proposed activities toward CO2-neutral and bio-feedstock-compatible multifunctional LOHCs, as well as more low-cost and thermally stable options, are needed to adapt LOHC technologies for a scalable sustainable hydrogen economy.