| Institution: | 1. National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029 Anhui, P. R. China
These authors contributed equally to this work.;2. National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, 230029 Anhui, P. R. China;3. School of Chemistry and Chemical Engineering, Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, Shihezi University Shihezi, 832003 Xinjiang, P. R. China |
| Abstract: | Synthesis of highly active and durable oxygen evolution reaction (OER) catalysts applied in acidic water electrolysis remains a grand challenge. Here, we construct a type of high-loading iridium single atom catalysts with tunable d-band holes character (h-HL?Ir SACs, ～17.2 wt % Ir) realized in the early OER operation stages. The in situ X-ray absorption spectroscopy reveals that the quantity of the d-band holes of Ir active sites can be fast increased by 0.56 unit from the open circuit to a low working potential of 1.35 V. More remarkably, in situ synchrotron infrared and Raman spectroscopies demonstrate the quick accumulation of *OOH and *OH intermediates over holes-modulated Ir sites in the early reaction voltages, achieving a rapid OER kinetics. As a result, this well-designed h-HL?Ir SACs exhibits superior performance for acidic OER with overpotentials of 216 mV @10 mA cm?2 and 259 mV @100 mA cm?2, corresponding to a small Tafel slope of 43 mV dec?1. The activity of catalyst shows no evident attenuation after 60 h operation in acidic environment. This work provides some useful hints for the design of superior acidic OER catalysts. |
