On the role of Fe species in NiOOH for oxygen evolution reaction
The Pourbaix diagram of Ni electrodes under reaction conditions presents several metastable NiOx Hy phases and Fe doping enlarges the stability area of oxyhydroxo nature. For the Ni-only phase water adsorption and intercalation can significantly lower both the surface and interface energies, and even introduce so-called negative surface energy. Thus, water can exfoliate layers leading to Fe ion adsorption on inner layers as demonstrated by ab initio molecular dynamics. These single atoms have been carefully speciated (i.e. initially prepared as Fe 2+ and Fe 3+ ) and hydrogen transfer between the H 2 O?Fe and lattice oxygen ions was observed in all ab initio molecular dynamics simulations, which is attributed to the Fe incorporation as no hydrogen transfer occurs in free water conditions. Furthermore, twelve possible oxygen evolution reaction mechanisms near Fe ions show that the main active species corresponds to the Ni 2+ , which is reduced from Ni 3+ by H transfer when a Fe 2+ adsorbs nearby, the overpotential can be significantly reduced to 0.23 V.
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Please use this identifier to cite or link to this collection:doi:10.19061/iochem-bd-1-147
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Manuscript title: On the role of Fe species in NiOOH for oxygen evolution reaction
Journal: ACS Catal.