As a rule, most catalyst materials deteriorate during repeated catalytic cycles—they age. But there are also compounds that increase their performance over the course of catalysis. One example is the mineral erythrite, a mineral compound comprising cobalt and arsenic oxides with a molecular formula of (Co3(AsO4)2∙8H2O). The mineral stands out because of its purple color. Erythrite lends itself to accelerating oxygen generation at the anode during electrolytic splitting of water into hydrogen and oxygen.
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Source: Phys.org