Molybdenum based materials have recently emerged as highly active electrocatalysts for the hydrogen evolution reaction (HER) [1, 2]. Molybdenum borides in contrary have not been extensively studied for their HER activity at the nanoscale, however they were recently shown to be already efficient HER catalysts in the bulk (microscale) . Recently, we reported the first nanoscale molybdenum boride, MoB2 nanospheres, which outperformed the microscale sample greatly . This prompted us to search for a general method for the synthesis of these materials at the nanoscale. Indeed, we have discovered a simple, one-step, low temperature solid state reaction capable of producing such nanocrystalline molybdenum borides. The structural and morphological characterizations were studied using XRD, XPS and electron microscopy. The obtained molybdenum borides nanostructures were tested for their electroactivity for HER in acidic conditions. We found a boron- and structural dependency of these nanoborides for the HER. Also, the obtained HER activity values represent a significant improvement from those observed for the already highly active bulk borides, thus opening a new avenue for inexpensive nanoscale metal boride nanomaterials s highly efficient HER catalysts.
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