Nano Mn-Ca oxide surrounded by polypeptides as a biomimetic catalyst for water-splitting systems

Introduction: In view of the increasing energy consumption, finding clean energy sources is a kind of essential demand in the worldwide. Among different compounds, hydrogen has been considered as an energy storing material. A promising way to produce hydrogen is through water splitting by electrochemical reactions [1].Water splitting composed of both hydrogen evolution reaction at cathode and oxygen evolution reaction at anode [2].Water oxidation is a bottleneck for water splitting and efficient catalysts are needed for reduction of oxidation potential.Materials and Methods: The compound was synthesized as follows: To 25 mg engineered polypeptide (Glu-Glu-Glu-Glu-Glu-Glu-Glu-His-Val-Val-Val-Val-Val-Val-Val-Val) in water, Mn(OAc)2 .4H2O and Ca(NO3)2 was added and stirred. Then, a solution of KMnO4 in water containing Ca(OH)2 (pH=9) was added at 4°C and the mixture was stirred for 30 min. A three-electrode system was utilized to survey the electrochemical properties of modified electrodes. Results and Discussion: The result stated that the potential of anodic peak for Mn(III)/Mn(IV) was declined to 1.0 V vs. Ag/AgCl/KClsat in the attendance of the polypeptide. The morphology of compound was containing a dispersed Mn-Ca oxide into an organic matrix. The functional groups in organic matrix cause a decrease in potential for Mn(III)/Mn(IV) oxidation peak. Conclusion: Engineered polypeptides show great promise for making new catalysts at the nanoscale levels for water oxidation. Using an engineered polypeptide, we could synthesize polypeptide/Mn-Ca oxide and applied it as a structural model for the water-oxidizing catalyst in photoststem II.

کلیدواژه ها:

Nano-sized MneCa oxide ، Hydrogen ، Water splitting