A major goal within the CO₂ electrolysis community is to replace the generally used Ir anode catalyst with a more abundant material, which is stable and active for water oxidation under process conditions. Ni is widely applied in alkaline water electrolysis, and it has been considered as a potential anode catalyst in CO₂ electrolysis. Here we compare the operation of electrolyzer cells with Ir and Ni anodes and demonstrate that, while Ir is stable under process conditions, the degradation of Ni leads to a rapid cell failure. This is caused by two parallel mechanisms: (i) a pH decrease of the anolyte to a near neutral value and (ii) the local chemical environment developing at the anode (i.e., high carbonate concentration). The latter is detrimental for zero-gap electrolyzer cells only, but the first mechanism is universal, occurring in any kind of CO₂ electrolyzer after prolonged operation with recirculated anolyte.

中文翻译：

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当地化学环境控制 CO2 电解槽中的阳极过程

CO ₂电解界的一个主要目标是用更丰富的材料代替常用的 Ir 阳极催化剂，该材料在工艺条件下对水氧化具有稳定和活性。Ni广泛应用于碱性水电解，被认为是CO _{2 中}潜在的阳极催化剂电解。在这里，我们比较了带有 Ir 和 Ni 阳极的电解槽的运行情况，并证明虽然 Ir 在工艺条件下是稳定的，但 Ni 的降解会导致电池快速失效。这是由两种平行机制引起的：(i) 阳极电解液的 pH 值降低到接近中性值和 (ii) 在阳极处形成的局部化学环境（即高碳酸盐浓度）。后者仅对零间隙电解槽有害，但第一种机制是普遍的，在使用再循环阳极电解液长时间操作后发生在任何类型的 CO ₂电解槽中。