Liu Xiyan, Gong Yu
Department of Radiochemistry, Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China.
School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, China.
Inorg Chem. 2021 Dec 6;60(23):18075-18081. doi: 10.1021/acs.inorgchem.1c02684. Epub 2021 Nov 9.
Molybdenum borides have been of interest due to their potential applications as electrocatalysts for the hydrogen evolution reaction (HER). As one of the common molybdenum borides, β-MoB is deemed to exhibit low electrocatalytic activity due to the presence of puckered B layers, and improvement of its behavior is hindered by the lack of convenient synthetic methods. Herein, we report the synthesis of crystalline β-MoB for the first time via the simple reaction of MoCl and B at 850 °C in LiCl-KCl. The as-prepared β-MoB sample was shown to exhibit a nanosheet structure with a large Brunauer-Emmett-Teller surface area of 48 m/g. Such β-MoB nanosheets exhibit promising HER activity in acidic medium with an overpotential of 187 mV at a current density of 10 mA/cm and a Tafel slope of 49.3 mV/decade, which is much better than that of the known bulk β-MoB and even close to the results of α-MoB that is commonly recognized as the best molybdenum boride electrocatalyst for HER. The high HER activity of β-MoB nanosheets results from the large surface area that allows more active sites to be exposed, which compensates for the disadvantage arising from the intrinsic structure of β-MoB.
硼化钼因其作为析氢反应（HER）电催化剂的潜在应用而备受关注。作为常见的硼化钼之一，β-MoB由于存在褶皱的B层而被认为具有较低的电催化活性，并且缺乏便捷的合成方法阻碍了其性能的改善。在此，我们首次报道了通过MoCl和B在850℃的LiCl-KCl中进行简单反应合成结晶β-MoB。所制备的β-MoB样品显示出具有48 m/g的大比表面积的纳米片结构。这种β-MoB纳米片在酸性介质中表现出有前景的HER活性，在电流密度为10 mA/cm时过电位为187 mV，塔菲尔斜率为49.3 mV/decade，这比已知的块状β-MoB要好得多，甚至接近通常被认为是HER最佳硼化钼电催化剂的α-MoB的结果。β-MoB纳米片的高HER活性源于大表面积，这使得更多活性位点得以暴露，弥补了β-MoB固有结构带来的劣势。
