Phosphate Coordination in a Water-Oxidizing Cobalt Oxide Electrocatalyst Revealed by X-ray Absorption Spectroscopy at the Phosphorus K-Edge
Round 1
Reviewer 1 Report
The authors put together a clear manuscript with sound analysis of what is often very challenging data to both collect and analyse. The reviewer found the results interesting and appreciated the concise presentation.
The measurements performed here appear to be limited to an ex situ characterisation of as preprared materials. From these the authors discount to role of P in the Co redox processes. However, under OER conditions the state of the catalysts dynamically changes likely forming a new phase on the surface, often considered to be an oxyhydroxide. Did the authors measure the samples in-situ or post mortem after OER? If not, it might be too simplistic to fully discount redox processes being influenced by the presence of P as the active surfaces are only formed during electrochemical reactions and the as prepared materials are often not representative of the electrocatalytic surfaces.
As a general comment, to perform in situ/operando, non-resonant X-ray emission spectroscopy could be a method that can provide information pertaining the the restructuring of the P in a technically less demanding configuration. This may be a direction to explore.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript by Liu et al. provided a cobalt‐phosphate catalyst for OER. Authors used X‐ray absorption spectroscopy experiments at the P K‐edge and analyze corresponding XANES and EXAFS spectra. The relations of catalyst‐internal phosphate ions to cobalt redox‐state changes, proton transfer, and catalytic activity are discussed. The manuscript might be accepted after some minor revisions.
1. In table 1, authors should add error values into Table.
2. Why authors fixed parameter for the CN of the first and second shell for P-O and P-O-Oms.
3. The CN = 0.1 for P-Co shell doesn’t make sense. Why that value is 0.1?
4. Overall, the readability of this work is not strong. Authors should polish their written.
normal level
Author Response
See attached file.
Author Response File: Author Response.pdf
