Saito Kenji, Jinushi Takahiro, Soga Itsuki
Department of Materials Science and Technology, Faculty of Engineering, Niigata University, 8050 Ikarashi 2-no-cho, Nishi-ku, Niigata 950-2181, Japan.
ACS Omega. 2024 Jan 31;9(6):7069-7074. doi: 10.1021/acsomega.3c09045. eCollection 2024 Feb 13.
Solid-state reaction (SSR) is a widely adopted method for functional inorganic material syntheses. Unlike intricate systems emerging from chemically unstable precursor usage, the SSR can proceed from stable precursor couples using simple apparatuses. However, this reaction is associated with high temperatures that overcome solid-state diffusion. Moreover, solid-state syntheses of technologically crucial carbides lead to greenhouse gas emissions. Therefore, exploring an extrinsic component to suppress these challenges is vital to confronting global energy and environmental issues. This study reports that the presence of an ordinary element, vanadium (V), changes the routes of the SSR of niobium carbide (NbC), producing NbC efficiently and cleanly. 1000 °C is far below the temperature required to obtain NbC from a precursor couple of NbO and C, i.e., approximately 1500 °C is required. However, a carbon substitute, vanadium carbide, completely consumed NbO before reaching 1000 °C and consummated NbC crystallization for 10 h. Furthermore, NbC crystallites were observed using X-ray diffraction from 770 °C, and their formation was primarily accompanied by VNbO, rather than being routed through NbO produced for the NbO-C combination. The obtained NbC contained V as a dopant in the 15-50% range (NbC:V), and the relative abundance was correlated with the preparation temperature. Mass analyses revealed that the formation of NbC/V is barely associated with greenhouse gas emissions because of the sizable thermodynamic driving force for primarily forming vanadium oxide byproducts. Device performance using NbC/V was also assessed for a standard electrochemical hydrogen evolution reaction.
固态反应（SSR）是一种广泛应用于功能性无机材料合成的方法。与使用化学性质不稳定的前驱体所产生的复杂体系不同，SSR可以使用简单的设备，从稳定的前驱体对开始进行反应。然而，这种反应与克服固态扩散所需的高温有关。此外，技术上至关重要的碳化物的固态合成会导致温室气体排放。因此，探索一种外在成分来抑制这些挑战对于应对全球能源和环境问题至关重要。本研究报告称，普通元素钒（V）的存在改变了碳化铌（NbC）的SSR路径，能够高效且清洁地生产NbC。1000℃远低于从NbO和C的前驱体对中获得NbC所需的温度，即大约需要1500℃。然而，一种碳替代物碳化钒在达到1000℃之前就完全消耗了NbO，并在10小时内完成了NbC的结晶。此外，在770℃时使用X射线衍射观察到了NbC微晶，其形成主要伴随着VNbO出现，而不是通过NbO-C组合产生的NbO路径。所获得的NbC含有15%-50%范围的V作为掺杂剂（NbC:V），且相对丰度与制备温度相关。质量分析表明由于主要形成钒氧化物副产物的巨大热力学驱动力，NbC/V的形成几乎与温室气体排放无关。还针对标准电化学析氢反应评估了使用NbC/V的器件性能。
