Abstract
Developing low-cost electrocatalysts to replace precious Ir-based materials is key for oxygen evolution reaction (OER). Here, we report atomically dispersed nickel coordinated with nitrogen and sulfur species in porous carbon nanosheets as an electrocatalyst exhibiting excellent activity and durability for OER with a low overpotential of 1.51 V at 10 mA cm−2 and a small Tafel slope of 45 mV dec−1 in alkaline media. Such electrocatalyst represents the best among all reported transition metal- and/or heteroatom-doped carbon electrocatalysts and is even superior to benchmark Ir/C. Theoretical and experimental results demonstrate that the well-dispersed molecular S|NiNx species act as active sites for catalyzing OER. The atomic structure of S|NiNx centers in the carbon matrix is clearly disclosed by aberration-corrected scanning transmission electron microscopy and synchrotron radiation X-ray absorption spectroscopy together with computational simulations. An integrated photoanode of nanocarbon on a Fe2O3 nanosheet array enables highly active solar-driven oxygen production.
Highlights
Developing low-cost electrocatalysts to replace precious Ir-based materials is key for oxygen evolution reaction (OER)
To improve the overall catalytic activity, more efforts should be devoted to clarify the active sites of transition metal (TM)–Nxdoped nanocarbons involved in the OER process for deciphering their actual catalytic mechanisms
Further theoretic investigations have demonstrated that the TM atom shows a high-reaction free energy for the adsorption of intermediate products owing to the strong electronegativity of neighboring N atoms, which increases the potential barriers in the reaction processes[26]
Summary
Developing low-cost electrocatalysts to replace precious Ir-based materials is key for oxygen evolution reaction (OER). We report atomically dispersed nickel coordinated with nitrogen and sulfur species in porous carbon nanosheets as an electrocatalyst exhibiting excellent activity and durability for OER with a low overpotential of 1.51 V at 10 mA cm−2 and a small Tafel slope of 45 mV dec−1 in alkaline media. Such electrocatalyst represents the best among all reported transition metal- and/or heteroatom-doped carbon electrocatalysts and is even superior to benchmark Ir/C. The achieved S|NiNx−PC/EG nanosheets delivers a high OER performance with a low overpotential of 1.51 V at 10 mA cm−2 and a small Tafel slope of 45 mV dec−1 and are superior to all reported transition metal- and/or heteroatom-doped carbon catalysts and even the commercial Ir/C benchmark catalyst (1.59 V at 10 mA cm−2) in alkaline media
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