Evidence of hydroxyl adsorption promotion by FeOOH. (a) Illustration of the mechanism of hydroxyl adsorption with structure change. (b) Time-dependent ICP-MS and ICP-AES of LNO and Fe-LNO; test with chronopotentiometry holds at 10 mA/cm2. (c) Hydroxyl adsorption experiment by pH study. (d) O 2p XPS spectra of the Fe-LNO and LNO. (e) Cyclic voltammograms and hydroxyl adsorption voltage ranges by DFT calculations; the solid line represents the cyclic voltammograms of samples, and the dashed line is the prediction voltage ranges. (f) In situ Raman spectra of Fe-LNO and LNO at 1.23 V vs. RHE. (g) In situ Raman spectra of Fe-LNO and LNO in different voltages.