Abstract
Multiscale engineering of efficient catalysts to optimize the adsorption energy of intermediates (atomic level) and achieve rapid mass transfer (three-dimensional (3D) bulk level) is crucial for boosting overall water splitting. In this work, we first create oxygen vacancies in nickel–iron hydroxide and then transform the hydroxide into NiFe-Vo-P having a nanoarray morphology via phosphorization. During the oxygen evolution reaction, Ni(Fe)OOH and phosphate anions can be in situ formed on the NiFe-Vo-P surface and optimize the adsorption strength of the intermediates. Consequently, NiFe-Vo-P could achieve a high current density of 1.5 A cm−2 at an overpotential of 289 mV. Moreover, the superhydrophilic/superaerophobic nanoarray morphology of NiFe phosphide effectively facilitates the mass transfer, and NiFe-Vo-P achieves current densities of 580 mA cm−2 and 1.0 A cm−2 at a cell voltage of ∼2.0 V at 25 and 70°C, respectively, over twice those of its counterpart without the superaerophobic morphology.
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