Molybdenum based materials have recently emerged as highly active non-noble metal electrocatalysts for hydrogen evolution reaction (HER) [1, 2]. Molybdenum borides in contrary have not been studied for their HER activity at the nanoscale, however, they were recently shown to be already efficient HER catalysts in the bulk [3]. In this study, we have successfully synthesized nanocrystalline molybdenum boride nanowires (MoB) and nanospheres (MoB₂) using a simple, one-step, solid state reaction. The structural and morphological characterizations were studied using XRD, XPS and electron microscopy. The obtained molybdenum borides nanostructures were tested for their electrocatalytic activity for HER in acidic conditions. We found that, nanoscale MoB₂ exhibits a low onset overpotential and low Tafel slope value compared to nanoscale MoB indicating a boron- and structural dependency of these nanoborides for the HER. Also, the onset overpotential and Tafel slope values obtained represent a significant improvement from those observed for the already highly active bulk borides [3], thus opening a new avenue for inexpensive nanoscale metal boride nanomaterials as highly efficient non-noble metal HER catalysts.

References:

1. H. Vrubel and X. L. Hu, Angew. Chem. Int. Ed., 55 (2012) 12703-12706.
2. P. Xiao, M. A. Sk, L. Thia, X. M. Ge, R. J. Lim, J. Y. Wang, K. H. Lim and X. Wang, Energy Environ. Sci., 7 (2014) 2624-2629.
3. H. Park, A. Encinas, J. P. Scheifers, Y. Zhang and B. P. T. Fokwa, Angew. Chem. Int. Ed., 56 (2017) https://doi.org/10.1002/anie.201611756.