Electric field polarized sulfonated carbon dots/NiFe layerd double hydroxide as highly efficient electrocatalyst for oxygen evolution reaction

Abstract

The SO 3 -CDs/NiFe LDH was synthesized through electrochemical and hydrothermal methods. The P-SO 3 -CDs/NiFe LDH catalyst work electrode was obtained via polarized by an electric field of 10,000 V/cm for 30 mins. After that, sulfonate functional groups selectively enrich at the surface of catalysts. Such sulfonate functional groups have a strong ability to capture proton, exhibit excellent OER performances as confirmed by DFT calculation and experimental results. • NiFe LDH/CDs composite was employed as OER catalysts. • Electric field polarization is used to regulate the exposed functional groups. • H + captured from *OH or *OOH species by the sulfonated groups on CDs. • The overpotential is 200 mV@10 mA cm −2 and Tafel slope is 55.2 mV dec −1 . • Polarized catalysts reach a high current density than the unpolarized one. Interfacial design and regulation for electrocatalysts can effectively enhance the performance of oxygen evolution reaction (OER). It is still a challenge to search for a simple and easy way to controllably adjust the interface of catalysts. Here we report a new strategy, electric field polarization to regulate the charged functional groups of nickel–iron layered double hydroxide (NiFe LDH)/carbon dots (CDs) composite catalysts. The selectively exposed sulfonate functional groups on CDs under the electric field have regulated the interfacial environment of the composite catalyst. The density function theory (DFT) calculation also reveals that the high electrocatalytic activity can be attributed to H + capture from *OH or *OOH species by the sulfonated groups on the surface of CDs. Thus, the synergistic effect between the catalytic activity of NiFe LDH and the functional group-modified CDs enhances the OER performance of the composite catalyst, showing low overpotential of 200 mV at 10 mA cm −2 and outstanding kinetics with Tafel slope of 55.2 mV dec −1 . Moreover, the polarized composite catalysts can reach a high current density of 51.7 mA cm −2 at 1.46 V vs. reversible hydrogen electrode (RHE), which is 9.2 times higher than the unpolarized one (5.6 mA cm −2 ).