本研究以PMOD(Photochemical metal-organic deposition)法製備金屬氧化物觸媒，由於其製備溫度及設備成本低，製程也相當簡單，有助於量產。在產氧觸媒中，大多數催化效率好的電極材料為稀有或貴重金屬，如RuO2。找出在環境中擁有高含量且非貴重或稀有金屬的材料，並提升其產氧催化效率，為此次研究的主要目標。Niobium在地層中被發現擁有高的含量，且具有催化活性，其Corrosion resistance也相當地好，因此在這次電極製備上，添加了少許Niobium在金屬氧化物中。

由Cyclic voltammetry曲線可以了解，在產氧反應中當電流密度到達0.5 mA cm-2時，Nb20Co40Fe40Ox的電位為1.52 V，而CoOx、FeOx及NbOx的電位分別為1.46 V、1.63 V及2.2 V，顯示了CoOx是個不錯的產氧催化材料。在Tafel slope方面，Nb20Co40Fe40Ox的值為31 ± 5 mV dec-1，相較於CoOx的42 ± 2 mV dec-1，顯示了Nb20Co40Fe40Ox擁有高的產氧催化活性。一個優良的產氧電極除了高的產氧催化活性外，也須擁有好的穩定度，為了確認電極在產氧反應中的穩定性，因此做了OER stability tests。在定電流時(1 mA)，當掃描時間過了1800秒，Nb20Co40Fe40Ox及CoOx的potential increased rate分別為3.29 %及39.25 %。此外，利用CV cycling來觀察各個金屬氧化物的穩定度，可得知當第500個cycle時，Nb20Co40Fe40Ox及CoOx的在到達1 mA時的電位附近，Current density loss分別為25.07 %及46.04 %。由上述這些數據顯示了Nb20Co40Fe40Ox在產氧反應中，無論是催化活性或是穩定度都相當地好，可以作為一個優良的產氧觸媒。

Metal oxides are considered as the stable catalysts which have high catalytic activity for oxygen evolution reaction (OER), such as IrO2, spinel solids and amorphous metal oxides. In addition, amorphous metal oxides have been proved that they have potential to replace noble metal as OER materials. Niobium is abundant on earth’s upper crust, and its oxide has been proved to have photochemical ability to produce oxygen in water splitting. Besides, Niobium is recognized for having excellent stabilization capacity. As a result, a system is expected to present an excellent resistance to anodic corrosion.Therefore, this research will focus on the series of Niobium oxides for OER. Photochemical metal-organic deposition (PMOD) is one of the best ways to make amorphous thin films, due to the cost of this process is cheap, operating temperature and pressure are low, equipment is simple and it is suitable for multicomponent amorphous oxides preparation.

In order to check the kinetic performance of catalysts, cyclic voltammetry curve (CV) and Tafel slope is plotted. From the CV curve, as the current density reaches 0.5 mA cm-2, the potential of Nb20Co40Fe40Ox is only required 1.52 V. In addition, cobalt oxide, iron oxide and niobium oxide require potential 1.46 V, 1.63 V and 2.2 V, respectively. It shows that cobalt oxide has high catalytic activity for OER. From Tafel slope, the value of is 31 ± 5 mV dec-1, comparing to the tafel slope of CoOx (42±2 mV dec-1), it shows that Nb20Co40Fe40Ox has a relatively high catalytic activity. Not only high catalytic activity, but stabilty is also an important property of an excellent electrode. Therefore, in this study, I made the OER stability tests for the electrodes. Set the current density at 1 mA cm-2, as the scan time reached 1800 second, the potential increased rate of Nb20Co40Fe40Ox and CoOx are 3.29 % and 39.25 %, respectively. Beside, I used CV cycling to check the OER stability for metal oxides. At 500th cycle, the current density loss of Nb20Co40Fe40Ox and CoOx are 25.07 % and 46.04 %, respectively. From these results, they prove that Nb20Co40Fe40Ox has excellent stability and catalytic activity at oxygen evolution reaction.

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林智仁，場發射式掃描式電子顯微鏡簡介，工業材料雜誌第181期，96頁，民國91年。