Electrocatalytic activity of water oxidation by coordination polymer Copentacyanidoferrate(ll)

Strategies to develop new sources of green and sustainable energy to attend the global demand is a challenge for the scientific community. A promising alternative is the production of hydrogen from the process of water splitting. Water is an abundant molecule on Earth and can be decomposed into H2 and 0 2. Although the process seems simple, the water oxidation is thermodynamically and kinetically unfavorable and therefore requires a catalyst to overcome the energetic barrier. The challenges in the development of catalysts for water oxidation are: design of materials that operate under conditions of low overpotential; stability under conditions of strong oxidation; composition based on abundant elements in nature; high stability and robustness. Thus, the goal of this work was to evaluate the electrocatalytic properties for water oxidation by the coordination polymer produced by the reaction between cobalt(ll) and [Fe(CN)5(isn)]4·, (isn =isonicotinate). The films were deposited on FTO-electrodes. First the cobalt was reduced on the electrode and after this, the complex was deposited electrochemically (+0.3 V-vs-SCE for 6 hours). Figure-A presents the cyclic voltammograms of the Co-[Fe(CN)5(isn))4- (Prussian blue analogous) in different pH. Efficiency of the catalysis supported in the FTO substrates was evaluated by obtaining the Tafel plots of water oxidation and the determination of the over potential that were 146 mVdec-1 and 0.46 mV, respectively (Figure-B). The observed performance values are compatible with the best results described in the literature for this class of catalyst.