School of Basic Sciences, Indian Institute of Technology , Bhubaneswar, Odisha, India -751013.
CSIR-Institute of Minerals and Materials Technology , Bhubaneswar, Odisha, India -751013.
ACS Appl Mater Interfaces. 2017 Mar 22;9(11):9640-9653. doi: 10.1021/acsami.6b16250. Epub 2017 Mar 10.
Room-temperature stabilization of metastable β-NiMoO is achieved through urea-assisted hydrothermal synthesis technique. Structural and morphological studies provided significant insights for the metastable phase. Furthermore, detailed electrochemical investigations showcased its activity toward energy storage and conversion, yielding intriguing results. Comparison with the stable polymorph, α-NiMoO, has also been borne out to support the enhanced electrochemical activities of the as-obtained β-NiMoO. A specific capacitance of ∼4188 F g (at a current density of 5 A g) has been observed showing its exceptional faradic capacitance. We qualitatively and extensively demonstrate through the analysis of density of states (DOS) obtained from first-principles calculations that, enhanced DOS near top of the valence band and empty 4d orbital of Mo near Fermi level make β-NiMoO better energy storage and conversion material compared to α-NiMoO. Likewise, from the oxygen evolution reaction experiment, it is found that the state of art current density of 10 mA cm is achieved at overpotential of 300 mV, which is much lower than that of IrO/C. First-principles calculations also confirm a lower overpotential of 350 mV for β-NiMoO
通过尿素辅助水热合成技术实现了亚稳相β-NiMoO 的室温稳定。结构和形态研究为亚稳相提供了重要的见解。此外，详细的电化学研究展示了其在储能和转换方面的活性，得出了有趣的结果。与稳定的多晶型相α-NiMoO 的比较也支持了所获得的β-NiMoO 的增强的电化学活性。观察到约 4188 F g 的比电容（在 5 A g 的电流密度下），表现出其出色的法拉第电容。我们通过从第一性原理计算中获得的态密度（DOS）的分析定性和广泛地证明，与 α-NiMoO 相比，价带顶部附近的 DOS 和费米能级附近的 Mo 的空 4d 轨道的增强使β-NiMoO 成为更好的储能和转换材料。同样，从析氧反应实验中发现，在 300 mV 的过电势下实现了 10 mA cm 的艺术级电流密度，远低于 IrO/C 的过电势。第一性原理计算也证实了β-NiMoO 的过电势低 350 mV。
