Polymer electrolyte membrane fuel cells (PEMFCs) running on hydrogen are an attractive proposition, particularly as a power source for motor vehicles. In situ release of the required H 2 from a stable liquid ensures its safe storage and transportation before use. Use of methanol is especially attractive because it can reform itself with water to release H2. However, traditional reforming of methanol steam operates at relatively high temperatures of 200–350°C, and therefore the focus for vehicle and portable PEMFC applications has been on aqueous-phase reforming of methanol (APRM).
Now a group from Peking University (Beijing, China; www.pku.edu.cn) led by professor Ding Ma has reported a new catalyst — platinum atomically dispersed on a-molybdenum carbide (a-MoC) — enables low-temperature (150–190°C) base-free (avoiding the caustic hydroxide) H2 production through APRM, with an average turnover frequency of 18,046 moles of hydrogen per mole of platinum per hour. Ma attributes this to the outstanding ability of a-MoC to induce water dissociation and to the fact that platinum and a-MoC act in synergy to activate methanol and then to reform it.
Ma says that a 50-L tank of methanol and catalyst with 6–10 g of platinum could power a Toyota Mirai for about 690 km. The methanol would cost about $15, and the platinum about $320, but the catalyst is potentially recyclable. Ma says that automobile catalytic converters now contain 1–4 g of recyclable noble metals, so 8 g of platinum is not a comparably large number.
The type of catalyst developed by Ma and co-workers could also be useful for other aqueous-phase reforming processes, such as those involving bio waste or ethanol.