Taking cues from nature: Hemoglobin catalysed oxygen reduction

Boosting the electrochemical oxygen reduction activity of hemoglobin on fructose@graphene-oxide nanoplatforms

“…In addition, an evident increase of the limiting current density can be observed for both composites, being the best electrocatalytic performance for the one prepared under higher temperature, which can be attributed to the increased number of superficial pyridinic N active sites induced by the additional conformational changes. Both the resulting onset potential and limiting current density values for the GO-Fruc-Hb composites were very close to the ones previously reported for pyridine functionalized MWCNTs 24 and even surpassed by far some of the most proficient N-doped nanocarbons obtained from proteins, 27 demonstrating both the suitability of this novel alternative approach and the strong influence of pyridine-like nitrogens belonging to histidine residues on the final electrocatalytic yields. Figure 4D shows the obtained Koutecky-Levich (K-L) plots from the Figure S2 at -0.75 V. The excellent linearity demonstrates first-order reaction toward dissolved O2 for all samples.…”

“…Indeed, Figure 4B demonstrates that the corresponding ORR cathodic peaks were not presented under saturated N2 environment. It is worth to note that unlike previous works, 24 the electrocatalytic performance of the covalently attached hemoglobins is not related with the iron active sites owed to they were totally removed from the protein structure after the immobilization process. Therefore, although the electron donating effect of amine groups of protein framework cannot be rule out, we attributed the main electrocatalytic response to the role of pyridine-like nitrogens belonging to histidine residues, which are disposed in highly accessible positions at the electrochemical interface and in turn are able to transform the neighboring carbon atoms (carbon atoms next to pyridinic N) in ORR highly efficient catalytically active sites.…”

Thermal and light irradiation effects on the electrocatalytic performance of hemoglobin modified Co3O4-g-C3N4 nanomaterials for the oxygen evolution reaction

“…Hb is a tetrameric redox protein formed by four polypeptide chains in which each polypeptide domain encloses at least one iron active redox centre that provides both hierarchically structure and porous framework to the whole. This redox protein has been previously reported by Compton et al 35 and Franco et al 36 as an outstanding electrocatalytic biomaterial for ORR. Our characterization results demonstrate the beneficial effect between three components (i.e.…”

The mechanism of electrochemical reduction of hydrogen peroxide on silver nanoparticles

“…Figure 1 shows two example cyclic voltammograms and the corresponding scan rate dependence simulated from the above model. The disproportionation rate constant of hydrogen peroxide decomposition at the electrode is set to be 10 -5 m s -1 (see below); the initial concentration of hydrogen peroxide is 1.0 mM; the diffusion coefficients of hydrogen peroxide and oxygen are found in the literature to be 1.43 x 10 -9 and 1.96 x 10 -9 m 2 s -1 in room temperature, respectively; [28][29][30] as oxygen reduction reaction is irreversible, the effective electron transfer k 0 is set to be 10 -7 m s -1 , the transfer coefficient is 0.3 and each oxygen transfers two electrons during the reduction. In Figure 1a, the waiting times before commencing the linear potential sweep to the electrode t wait are set to be 20 s (the blue line)…”