Fig. 5: Theoretical insight for excellent ORR performances.
DFT calculations of the Ni(OH)2 interface. a I, Proton transfer (PT) at U = 0.5 V vs. RHE and U = 0.7 V vs. RHE. II, III, Water dissociation process on the outer surface of Ni(OH)2 and the optimized geometries of the initial, transition and final state. IV, *OOH protonation for 2e– ORR pathway (*OOH + H→H2O2, solid line) and *OOH dissociation for 4e– ORR pathway (*OOH + H→*O + H2O, dotted line) of Ni(OH) at U = 0.5 V and U = 0.7 V vs. RHE. The pink and yellow represent oxygen and hydrogen in water, respectively. b The optimized structure of ORR process. The blue, pink, white and yellow represent nickel, oxygen in Ni(OH)2 and hydrogen in Ni(OH)2 and H in water, respectively. c In situ ATR-SEIRAS spectra for Ni(OH)2/CNT and NiO/CNT at different potentials in O2-saturated 3.6 wt. % NaCl solution. d Intensity ratio of OOH and O2 from ATR-SEIRAS. e FT-IR spectra of Ni(OH)2/CNT before and after oxygen reduction reaction, respectively.
