Surface evolution of Zn doped-RuO under different etching methods towards acidic oxygen evolution

The exact role of atom etching in the surface properties and electrocatalytic oxygen evolution reaction (OER), which is a dynamic system, still remains unclear. Hence, to gain a deeper insight into the structure-activity relationship of acidic OER catalysts, we fabricated Zn-doped RuO 2 (Zn-RuO 2 ) nanospheres to trace their structure evolution by actively strengthening the etching process of Zn-RuO 2 during the catalytic process. We found that compared to pure pickling (C-Zn-RuO 2 ), in situ electrochemical etching (E-Zn-RuO 2 ) enables a more thorough surface evolution of the Ru center, ensuring superior OER activity through well-dispersed nanocrystals, more defects and an appropriate electronic structure. The resulting E-Zn-RuO 2 only requires 190 mV at a current density of 10 mA cm −2 . Furthermore, E-Zn-RuO 2 underwent a pre-oxidation and irreversible surface reconstruction to form a stable active surface, thus it can steadily operate for 60 h at the constant 10 mA cm −2 , obviously surpassing C-Zn-RuO 2 (15 h). Here, Zn atoms can not only promote the change of electronic structure during electrical activation, but they also elevate the OER activity in acidic media. Theoretical calculation confirms that the Ru-O band has been shortened after Zn doping, which is conducive to a longer lifetime. Besides, the water oxidation proceeds via a new mechanism, where the deprotonation of the -OH species can stabilize the -OO groups on the Ru sites. Compared to pure pickling, in situ electrochemical etching enables RuO 2 a more thorough surface evolution of the Ru center, ensuring superior OER activity through well-dispersed nanocrystals, more defects and an appropriate electronic structure.