TAILORING NOVEL MATERIALS FOR GLOBAL CO_2 RECYCLING

结合人类活动的发展，为防止二氧化碳排放引起的全球变暖，我们提出了一个二氧化碳回收系统。该系统由二氧化碳的甲烷化组成，这些二氧化碳在燃料消耗点（如发电厂）回收。甲烷化需要高活性催化剂和氢气，而氢气可从太阳能电解海水中获得。为了在全球范围内实现这一体系，我们需要开发低成本、高效率的催化剂和电极，用于海水电解的析氢和析氧反应。本研究的目的是开发这种新的催化剂和电极物质。我们发现非晶Ni-Zr合金制备的甲烷化催化剂具有较高的甲烷化活性。以Ni-Zr-Sm非晶态合金为前驱体，成功研制出活性更高的催化剂。结果表明，钐稳定了氧化锆的四方相，在其上Ni - p - p的分散性也得到了增强。气雾化Ni-Zr-Sm合金制备的催化剂也具有较高的活性。溅射沉积制备的Ni-Mo和Co-Al-Mo合金电极具有较高的析氢活性。电弧离子镀不仅提高了Ni-Mo合金电极与基体的附着力，而且提高了电极的析氢效率；在电流密度为4×10^3A/m^2时，Ni-(10-20)和%Mo-(5-10)在%O时的析氢过电位小于100 mV。将MnO_2型氧化物电极安装在钛柱上，成功制备出100%析氧效率的海水电解电极。制备的电极结构为化学均匀的γ-MnO_2结构的纳米氧化锰，含有固溶六价钨。在海水电解过程中，Mo和W的联合添加对选择性析氧更有效，并且我们能够成功地降低电解电压。少

We are proposing a CO_2 recycling system for preventing global warming caused by CO_2 emissions in conjunctions with development of human activities. The system contsists of methanation of CO_2 which are recovered at fuel consumers sites such as power plants. Methanation needs highly active catalysts and hydrogen which can be obtained from seawater electrolysis using solar energy. To substantiate this system global scale, we need to develop low cost catalysts and electrode with high efficiency for hydrogen evolution and oxygen evolution reactions at seawater electrolysis. The objectives of this investigation are to develop such new catalysts and electrode substances.We have found methanation catalysts prepared from amorphous Ni-Zr alloys have high activity for methanation. We have also succeeded in develop more active catalyst using amorphous Ni-Zr-Sm alloys as precursors of the catalysts. It was clarified that samarium stabilize tetragonal phase of zirconia on which dispersion of Ni p … More articles are also enhanced. Catalysts prepared from gas-atomized Ni-Zr-Sm alloys also had high activity.Ni-Mo and Co-Al-Mo alloy electrode fabricated by sputter-deposition showed high activity for hydrogen evolution reaction. By using arc-ion-plating method, not only adhesiveness to the substrate but also hydrogen evolution efficiency of Ni-Mo alloy electrode was improved ; the most effective composition was Ni-(10-20)at%Mo-(5-10)at%O with the overpotential for hydrogen evolution lower than 100 mV at the cuurent density of 4×10^3A/m^2.It was succeeded to prepare an electrode with 100% oxygen evolution efficiency for seawater electrolysis using MnO_2 type oxide electrode installed on titanium stubstrate. The structure of the prepared electrode consisted of chemically homogeneous nanocrystalline manganese oxide with γ-MnO_2 structure containing solid-solved hexavalent tungsten. It was also found combined addition of Mo and W is more effective for selective oxygen evolution at seawater electrolysis and we were able to reduce electrolysis voltage successfully. Less