基于抑制Ti基体氧化的不连续薄膜形稳阳极

Developing of anodes with long lifetime has been one of the major challenges for the chlor-alkali process. For dimensionally stable anodes (DSA), the anodic reaction mainly consists of the chlorine evolution reaction (CER) accompanied by a small oxygen evolution reaction (OER) contribution. When the OER is competing with the CER, the efficiency of Cl2 production decreases, whereas the OER increases gradually, which facilitate the formation of a passivating film (TiO2) between the Ti substrate and the coating catalyst, resulting in the deactivation of DSA. In this application, non-continuous film of metal oxides (IrO2 and IrO2-MO, MO=MnO2、Co3O4、CuxCoyO4) will be deposited on the surface of the Ti substrate by regulating the parameters of magnetron sputtering. The presence of non-continuous film on the Ti substrate can effectively prevent the growth of a TiO2 insulating layer between the Ti substrate and the coated catalysts. The addition of an appropriate amount of Sn and Sb could also form a substitution solid solution due to the Sn4+ and Sb3+ ions having ionic radii similar to those of Ru4+ and Ti4+, which increase the potential difference between the CER and OER. Therefore, it will suppress the OER and further reduce the intermediate species produced by water oxidation over the oxidation of the Ti substrate. The obtained anodes display higher lifetime during the chlor-alkali electrolysis.

研制长效的氯化钠电解形稳阳极对氯碱工业具有重要的意义。针对现有形稳阳极（DSA）存在Ti基体与涂层界面间易生成TiO2钝化膜，氯氧电位差逐渐减小等问题，本研究通过在Ti基体表面沉积不连续的IrO2或IrO2-MO（MO=MnO2、Co3O4、NixCoyO4）薄膜，将水氧化的中间物种催化氧化为氧气离开电极进入溶液，抑制这些中间物种对Ti基体氧化，形成TiO2钝化膜。通过改变溅射参数和溅射条件，调控薄膜的厚度、形貌和组成，形成不连续多孔结构，提高表面粗糙度，并结合烧结方法将离子半径与RuO2相近的锡、锑氧化物掺杂到RuO2涂层中，形成固溶体氧化物，使阳极催化剂具有较大的析氯析氧电位差，析氧反应得到明显抑制，进而减少水氧化形成的中间物种对Ti基底的氧化，延长电极的使用寿命。

氯碱工业作为国民经济的基础产业，其耗能巨大，严重制约了该行业的发展。目前广泛使用的金属阳极是以钛为基体，RuO2和TiO2为电催化剂基本组分的一种形稳阳极（DSA），其存在涂层表面裂纹较大，Ti基体与涂层界面间易生成TiO2钝化膜，经过长期工作后，析氯过电位开始逐渐增大，氯氧电位差减小，导致电极催化析氯反应的选择性下降。因此，如何提高Ti基体的抗氧化性能，增加DSA电极的使用寿命，是实现高效、节能、长效的氯碱工业的必由之路。课题组采用磁控溅射、热分解、静电纺丝、水热合成等多种方法设计、制备了一系列抑制Ti基氧化的不连续薄膜形稳阳极DSA材料；通过材料测试表征手段和电化学测试方法考察阳极催化剂的表面组成、结构、价态以及微观形貌等因素对阳极析氯选择性和稳定性的影响，揭示了金属氧化物对电解析氯反应的选择性影响因素，建立了电极几何及电子结构、多元复合组分之间相互键合及协同作用等对其活性和稳定性的影响关系；筛选出的形稳阳极催化剂具有最优的析氯选择性，在电流密度150 mA/cm2时，析氯析氧电位差450 mV, 较对比电极增大了约150mV；制备了符合实验室小试的氯碱电解槽，选取所制备的最优析氢、析氯电极进行测试，探讨了实际工作状态电极的催化性能，并在相同条件下与工业电极进行对比，槽电压降低约200 mV，理论电解能耗降低超过10%，达到预期目标。