ZnO/Co-doped Polyhistidine As an Efficient Bioelctrocatalyst for Hydroxyl Radical Generation: Fabrication, Characterization and Application for Microbial Inactivation

The hydroxyl radical (& BULL;OH) is a well-known powerful oxidizing agent that can react unselectively with the environmental contaminants. Electrochemical radical generation has been regarded as a promising choice to enable H2O2 formation and its converting to & BULL;OH. Here, by modifying of zinc oxide with cobalt doped poly-histidine (Co:pHis), we succeeded in fabricating a new, efficient, and stable bioelectrocatalyst for converting the two-electron water oxidation reaction (2e-WOR) product to & BULL;OH. The structural, morphological and electro-chemical properties of fabricated bioelectrocatalyst were investigated by different characterization techniques. The functional groups of pHis increased the rate of 2e-WOR due to the formation of hydrogen bonding with H2O2. The presented bioelectrocatalyst gives an overpotential of 2.6 V (vs. RHE) at 0.2 mA/cm2 and peak Faradaic efficiency of 57% toward & BULL;OH generation. The electrogenerated & BULL;OH by the proposed new bio-electrocatalyst was successfully applied for the inactivation of E. coli (>95%) as a typical microbial contaminant.