Joint Study on the Photochemical and Catalytic Conversion of the Gases Causing the Rise in Earth's Temperature and the Decomposition of Ozone Layr to Innocuouc Species

如前所述，将引起地球温度上升和臭氧层分解的气体转化为无害物质是一个紧迫而重要的课题。从发达国家的能源状况和不发达国家的经济状况来看，用法律来控制这些有害气体的排放几乎是不可能的。因此，本研究开发了一种光催化和/或电催化的方法将这些气体转化为无害的物质，这种方法可以在低输入能量下进行，而电化学方法将CO_2转化为更复杂的化合物是很有前途的，因为这种反应在室温下进行，并且有可能发展成类似于光合作用的过程。然而，该技术的缺点是需要高度负的过电位。为了降低CO_2还原所需的过电位，我们开发了由无机导体和导电聚合物（如普鲁士蓝和聚苯胺）组成的双层膜修饰电极的电催化过程。该电极在较低的过电位下产生甲酸和乳酸的还原产物，并在H_2O存在下光解了CFC-113、CHCl_3和CCl_4，其分解产物用金属粉末清除。这些有害化合物的分解几乎是100%。所有氯原子都以金属氯化物的形式固定下来，除CO_2外没有气态产物存在。所产生的活性物质的清除反应是由金属的氧化引起的，因此二价和三价金属化合物仅显示出不显著的清除效率。

As pointed out, the conversion of the gases causing the rise in earth's temperature and the decomposition of ozone layr to innocuous species is a pressing and important subject. Taking thought for energy situation of advanced countries and the economical stuation of underdeveloped countries, it is almost imposible to control the discharge of these noxious gases by law. Accordingly, in the present study, a photocatalytic and/or a electrocatalytic processes to convert these gases to innocuous spesies, which can take place under low input energy, has been developed.The electrochemical conversion of CO_2 to more complex compounds is assumed to be promising since this reaction occurs at room temperature and has the possibility of being developed into a process similar to photosynthesis. However, a fault of this technique is requirement of a highly negative overpotential. In order to mitigate the overpotential required for the reduction of CO_2, we have developed the electrocatalytic process at the modified electrode having two laminated films consisting of an inorganic conductor and a conducting polymer such as Prussian blue and polyaniline, respectively. This electrode gave the reduction products involving formic and lactic acids at a much lower overpotential than that hitherto acieved.Chlorofluorocarbon (CFC-113), CHCl_3 and CCl_4 have been photolysed in the presence of H_2O,and the decomposed species scavenged by the reaction with a metal powder. The decomposition of these hazardous compounds was almost 100%. All chlorine atoms were fixed in the form of metal chloride, and no gaseous product existed except CO_2. The scavenging reaction of generated reactive species was brought about by the oxidation of the metal, and hence divalent and trivalent metal compounds showed only insignificant scavenging efficiency.