Electrocatalytic Water Oxidation Beginning with the Cobalt Polyoxometalate [Co_4(H_2O)_2(PW_9O_(34))_2]~(10-): Identification of Heterogeneous CoO_x as the Dominant Catalyst

摘要

The question of "what is the true catalyst?" when beginning with the cobalt polyoxometalate (POM) [Co_4(H_2O)_2(PW_9O_(34))_2]~(10-) in electrochemical water oxidation catalysis is examined in pH 8.0 sodium phosphate buffer at a glassy carbon electrode. Is [Co_4(H_2O)_2-(PW_9O_(34))_2] a true water oxidation catalyst (WOC), or just a precatalyst? Electrochemical, kinetic, UV-vis, SEM, EDX, and other data provide four main lines of compelling evidence that, under the conditions used herein, the dominant WOC is actually heterogeneous CoO_x and not homo-geneous [Co_4(H_2O)_2(PW_9O_(34))_2]~(10-).