Sugar Acid–Assisted Thermolysis of All-Solid-State Ammonia Borane Hydrogen Fuel

An all-solid-state hydrogen fuel composite composed of ammonia borane (AB), a chemical hydride containing 19.6 wt% hydrogen, and mucic acid (MA) is used as a hydrogen fuel source in thermal dehydrogenation. AB thermolysis provides a hydrogen-driven proton-exchange membrane fuel cell with selective, on-demand hydrogen generation by simply heating the pellet-type composite. MA, a six-carbon sugar acid containing two carboxylic acid groups at the C1 and C6 positions and four hydroxyl groups at the C2, C3, C4, and C5 positions, forms an optimized composite with AB (AB:MA = 8:2) to undergo a thermal dehydrogenation reaction to produce 10.77 wt% pure H₂ at 80 °C in 1 min. Adipic acid (AA), a six-carbon dioic acid without hydroxyl groups, is used as an analogue of MA and shows no catalytic effect in the AB+AA thermolysis process. It is believed that the AB+MA composite obeys the conventional alcoholysis mechanism in the thermolysis process.