Abstract
Oxygen evolution reaction (OER) is key for electrochemical water splitting. Catalysts minimized in single-atom level (SACs) anchored on two-dimensional substances are highly active for various electrocatalytic reactions, but so far represent the limited performance for OER. Herein we report a general strategy for the fabrication of bi-metal Ni and Fe SACs loaded on graphene to significantly boost the OER activity. Notably, this unique structure of single Ni and Fe atoms co-existed on graphene has a strong synergetic effect, which can substantially elevate the charge transfer of catalysts. As a result, the obtained bi-metal SACs with the appropriate ratio of 4 for single Ni and Fe atoms show a small overpotential of 247 mV at 10 mA·cm−2 of OER current density in KOH electrolyte, outperforming individual-metal Ni (329 mV) or Fe (384 mV) SACs. Furthermore, such catalyst exhibits excellent stability without significant decay with increasing time at high current of 20 mA·cm−2 continuously for 48 hours. This work provides a new avenue for regulating the properties of transition metal SACs on graphene for water electrolysis.
Highlights
Water splitting utilized by electric energy is an efficient way for the store of discontinuous and sustainable energies (Fan et al, 2016; Seitz et al, 2016; Zhang B. et al, 2016)
To improve the Oxygen evolution reaction (OER) activity of single atom catalysts (SACs), we considered whether the synergetic effect of dual-metal SACs could be applied on OER
Since graphene oxide (GO) are rich in hydroxyl and carboxyl groups, Ni2+ and Fe3+ ions were readily adsorbed on the surface of GO sheets via the functional oxygenated groups, e.g., hydroxyls and carboxyls (Gao et al, 2017)
Summary
Water splitting utilized by electric energy is an efficient way for the store of discontinuous and sustainable energies (Fan et al, 2016; Seitz et al, 2016; Zhang B. et al, 2016). The coupling effect of Ni, Fe single atoms could efficiently boost the activity and charge transfer of Ni, Fe-O-G SACs by tuning the Ni/Fe ratio.
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