The electrochemical behaviour of isopoly- and heteropolyoxomolybdates formed during anodicoxidation of molybdenum in seawater at constant current intensity was investigated in this work. Theresults supported by spectrophotometry clearly indicate the formation of mixed valence molybdates(V/VI) during this process. The electrochemical behaviour of isopolyoxomolybdates shows a typicalquasi-reversible mass-transport limited system coupled with an adsorption of reduced species andunder some kinetic limitations. For heteropolyoxomolybdates a reversible mass-transport limitedsystem coupled with an homogeneous chemical reaction was found. The coupled reaction, probablyprotonation, prevents a rapid heterogeneous electron transfer for heteropolyoxomolybdate complex.The phenomenon is more noticeable for the phosphomolybdate complex since the protonation step hasa greater influence on the registered voltammograms. The presented results have a great importance inresearch areas where molybdate chemistry is used in detection of silicate and phosphate, namely inseawater.
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