Alfke Jan L, Müller Andreas, Clark Adam H, Cervellino Antonio, Plodinec Milivoj, Comas-Vives Aleix, Copéret Christophe, Safonova Olga V
Department of Chemistry and Applied Biosciences, ETH Zurich, Vladimir Prelog Weg 2, Zurich, Switzerland.
Paul Scherrer Institute, Forschungsstrasse 111, CH-5232 Villigen, Switzerland.
Phys Chem Chem Phys. 2022 Oct 12;24(39):24429-24438. doi: 10.1039/d2cp03593f.
Metallic copper generally adopts an FCC structure. In this work, we detect highly unusual BCC-structured Cu nanoparticles as a transient intermediate during the H reduction of a Cu precursor, [CuOBu], grafted onto the surface of partially dehydroxylated silica. The Cu BCC structure, assigned by Cu K-edge XANES and EXAFS, as well as synchrotron PXRD, converts upon heating into the most commonly found FCC allotrope. DFT calculations show that the BCC-Cu phase is in fact predicted to be more stable for small particles, and that their stability increases at lower H concentrations. Using this knowledge, we show that it is possible to synthesize BCC-structured Cu nanoparticles as a stable allotrope by reduction of the same grafted precursor either in 10% H diluted in Ar or 100% H at low temperature.
金属铜通常采用面心立方（FCC）结构。在本研究中，我们检测到高度不寻常的体心立方（BCC）结构的铜纳米颗粒，它们是在接枝到部分脱羟基二氧化硅表面的铜前驱体[CuOBu]的氢还原过程中的一种瞬态中间体。通过铜K边X射线吸收近边结构（XANES）和扩展X射线吸收精细结构（EXAFS）以及同步辐射粉末X射线衍射（PXRD）确定的BCC结构的铜，在加热时会转变为最常见的FCC同素异形体。密度泛函理论（DFT）计算表明，实际上预测BCC结构的铜相对于小颗粒更稳定，并且在较低氢浓度下其稳定性会增加。利用这一知识，我们表明通过在氩气中稀释10%的氢气或在低温下的100%氢气中还原相同的接枝前驱体，可以合成作为稳定同素异形体的BCC结构的铜纳米颗粒。
