Understanding the relationship between the structural evolution of electrocatalysts and their catalytic activity is important but challenging. Based on this,King Abdullah University of Science and TechnologyProfessor Zhang Huabin et alThe effect of structural disorder on the activity of Fe-Ni hydroxide catalyst OER during dynamic structural evolution was studied by using Oprando X-ray absorption spectroscopy and other experimental and theoretical calculations under oxygen evolution reaction (OER) conditions, and this correlation was studied. The Debye-Waller factor obtained from the extended X-ray absorption fine structure analysis reflects the degree of structural disorder and shows a strong correlation with the intrinsic OER activity of the electrocatalyst.
VASP Interpretation
Using spin-polarized DFT calculations, the authors investigated the OER activity mechanism between catalysts. Firstly, the effect of structural disorder on the charge transfer of the catalyst is studied, and the results show that compared with the D-Fe-Ni-OOH model, the D(S)-Fe-Ni-OOH model has more electron consumption accumulation, i.e., more efficient charge transfer. The band structure simulations of the two models show that the D(S)-Fe-Ni-OOH catalyst has better conductivity than the D-Fe-Ni-OOH catalyst. The calculated total density of states (TDOS) revealed the electron transfer rate sequence: d(se)-fe-ni-ooh d(s)-fe-ni-ooh d(o)-fe-ni-ooh d-fe-ni-ooh d(o)-fe-ni-ooh d-fe-ni-ooh, indicating that the more disordered the structure of the catalyst has easier charge transfer and better electronic conductivity, which helps to improve its catalytic activity against OER.
The authors also calculated the free energy maps of OER at Fe and Ni sites in different models, and the thermodynamic overpotentials of the D-Fe-Ni-OOH and D(O)-Fe-Ni-OOH catalysts OER were 930 mV and 560 mV, respectively, both at the Ni site. The nine active sites of D(S)-Fe-Ni-OOH and D(Se)-Fe-Ni-OOH were Fe sites, and the corresponding overpotentials were 500 mV and 490 mV, respectively. The theoretically calculated overpotential trends are d(se)-fe-ni-ooh < d(s)-fe-ni-ooh < d(o)-fe-ni-ooh < d-fe-ni-ooh, and the results show that the higher the structural disorder, the higher the oer activity.
correlating structural disorder in metal (oxy)hydroxides and catalytic activity in electrocatalytic oxygen evolution. angew. chem. int. ed.,, doi: ht-tps: