Abstract
Designing efficient single-atom catalysts (SACs) for oxygen evolution reaction (OER) is critical for water-splitting. However, the self-reconstruction of isolated active sites during OER not only influences the catalytic activity, but also limits the understanding of structure-property relationships. Here, we utilize a self-reconstruction strategy to prepare a SAC with isolated iridium anchored on oxyhydroxides, which exhibits high catalytic OER performance with low overpotential and small Tafel slope, superior to the IrO2. Operando X-ray absorption spectroscopy studies in combination with theory calculations indicate that the isolated iridium sites undergo a deprotonation process to form the multiple active sites during OER, promoting the O–O coupling. The isolated iridium sites are revealed to remain dispersed due to the support effect during OER. This work not only affords the rational design strategy of OER SACs at the atomic scale, but also provides the fundamental insights of the operando OER mechanism for highly active OER SACs.
Highlights
Designing efficient single-atom catalysts (SACs) for oxygen evolution reaction (OER) is critical for water-splitting
We identify, by employing operando X-ray absorption spectroscopy (XAS) and density functional theory (DFT) calculations, that the isolated Ir atoms undergo a variation from the single active site to multiple active sites through a deprotonation process during the OER process, which are responsible for the superior catalytic performance
In summary, we developed a novel single-atom Ir incorporated into Ni(Fe) oxyhydroxides catalyst for OER, by utilizing the surface reconstruction of nanoporous Ni (Fe) phosphides
Summary
Designing efficient single-atom catalysts (SACs) for oxygen evolution reaction (OER) is critical for water-splitting. Though great efforts have been made to develop the earth-abundant transition-metalbased catalysts, including metal oxides or hydroxides[5,6,7,8,9,10,11,12,13,14], borides[15,16], phosphides[17,18,19,20,21], sulfides[22,23], and selenides[24,25], as low-cost alternative for OER Their catalytic performance remains far from satisfactory. Using metal phosphides as a support to anchor single-atom are still rare They undergo surface self-reconstruction to form oxyhydroxides under OER conditions, providing abundant oxygen ligands for the anchoring of isolated atoms[18,19]. The surface Ni(Fe) oxyhydroxides can form a shrinkage structure during OER conditions, further fixing the isolated Ir atoms, causing the excellent stability
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