Nanocrystalline Mo2C as a Bifunctional Water Splitting Electrocatalyst

Mo2C is a well-known low cost catalyst for the hydrogen evolution reaction (HER), but the other water splitting half reaction, the oxygen evolution reaction (OER), has not been previously reported. To investigate both reactions and the origin of the catalytic sites, four synthesis methods were employed to prepare hexagonal Fe2N type Mo2C. A comparison of the HER activities in acidic and alkaline electrolyte and OER activities in alkaline electrolyte revealed that changes in synthesis route leads to morphological and surface composition variations resulting in different catalytic activities. In general, the trend in HER and OER activities show remarkably similar trends across the carbides synthesized via different routes irrespective of either electrolyte employed or reaction probed for electrocatalytic activities. Mo2C templated on multiwalled carbon nanotubes demonstrated the highest bifunctional catalytic activities, as well as superior electrochemical stability for both HER and OER.