Kang Ho-Young, Nam Dae-Hyun, Yang Ki Dong, Joo Wonhyo, Kwak Hoyoung, Kim Hyung-Ho, Hong Seong-Hyeon, Nam Ki Tae, Joo Young-Chang
Department of Materials Science & Engineering , Seoul National University , 1 Gwanak-ro , Gwanak-gu, 151-744 Seoul , Republic of Korea.
Research Institute of Advanced Materials , Seoul National University , 1 Gwanak-ro , Gwanak-gu, 151-742 Seoul , Republic of Korea.
ACS Nano. 2018 Aug 28;12(8):8187-8196. doi: 10.1021/acsnano.8b03293. Epub 2018 Aug 7.
Precise control of the oxidation state of transition-metal oxides, such as copper, is important for high selectivity of CO reduction in an aqueous condition to compete with the reduction of water. The phase of copper oxide nanofibers was controlled by predictive synthesis, which controls the nanoscale gas-solid reaction by considering thermodynamics and kinetics. The driving force of the phase transformation between the different oxidation states of copper oxide is calculated by comparing the Gibbs free energy of each of the oxidation states. From the calculation, the kinetically processable window for the fabrication of CuO in which monophase CuO can be fabricated in a reasonable reaction time scale is discovered. Herein, we report the monophase CuO nanofiber photocathode, which photoelectrochemically converted CO into methanol with over 90% selectivity in an aqueous electrolyte, and a hierarchical structure is developed to optimize the photoactivity and stability of the electrode. Our work suggests a rational design of the calcination strategy for precisely controlling the oxidation states of transition metals that can be applied to various applications in which the phase of the materials plays an important role.
精确控制过渡金属氧化物（如铜）的氧化态，对于在水性条件下实现一氧化碳还原的高选择性以与水的还原竞争至关重要。通过预测合成来控制氧化铜纳米纤维的相，这种方法通过考虑热力学和动力学来控制纳米级气固反应。通过比较氧化铜不同氧化态的吉布斯自由能，计算出氧化铜不同氧化态之间相变的驱动力。通过计算，发现了制备单相氧化铜的动力学可处理窗口，在此窗口内可以在合理的反应时间尺度内制备单相氧化铜。在此，我们报道了单相氧化铜纳米纤维光阴极，其在水性电解质中能将一氧化碳光电化学转化为甲醇，选择性超过90%，并且开发了一种分级结构以优化电极的光活性和稳定性。我们的工作提出了一种合理设计煅烧策略的方法，用于精确控制过渡金属的氧化态，该方法可应用于材料相起重要作用的各种应用中。
