Electrocatalytic study of carbon dots/ Nickel iron layered double hydroxide composite for oxygen evolution reaction in alkaline medium

[Display omitted] •Facile synthesis of NiFe LDH@NDCDs composites with stacked nanosheets structure.•Superior electrocatalytic potential of the composite evidenced by lower over potential and have smaller Tafel slope values.•Enhanced electrochemical stability of the composite even at a high current density of 10 mA cm−2 for 6 h.•Enhancement of OER activity due to faster electron transfer from NDCDs to NiFe LDH. The synthesis and strategic deployment of inexpensive, efficient, and robust catalysts for the oxygen evolution reactions (OER) has assumed importance due to their key role in energy conversion and storage. In this work, Cyamopsis tetragonoloba extract derived nitrogen doped carbon dots (NDCDs) supported NiFe layered double hydroxide stacked sheets (NiFe LDH@NDCDs) had been successfully synthesized by easy solvothermal method. Structural morphology and crystalline nature of the synthesized NiFe LDH@NDCDs were characterized by Scanning electron microscopy (SEM), High resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction spectroscopy. The performance of the synthesized NiFe LDH@NDCDs in electrocatalytic oxygen evolution reaction (OER) was estimated by linear sweep voltammetry (LSV), Tafel, Electrochemical Impedance spectroscopy (EIS), cyclic voltammetry, and chronopotentiometry measurements in 0.1 M KOH. The synthesized NiFe LDH@NDCDs demonstrated the small overpotential of 0.385 VRHE to attain current density of 10 mA/cm2, which was lesser than NiFe LDH (0.425 VRHE), the state of the art (RuO2 = 0.422 VRHE), NDCDs (0.534 VRHE) and Bare Ni foam (0.541 VRHE). The calculated Tafel slopes of synthesized NiFe LDH@NDCDs showed smaller value (93 mV/dec) than NiFe LDH, RuO2, and Bare Ni foam. The EIS studies exposed that the total resistance (R1 + R2) of NiFe LDH@NDCDs (63.85 Ω/cm2) was lower than the total resistance of NiFe LDH (82.58 Ω/cm2) and resistance of Bare Ni foam (123.8 Ω/cm2), which revealed the good conductivity and electro activity of NiFe LDH@NDCDs. Moreover, the stability of the synthesized NiFe LDH@NDCDs was analyzed by chronopotentiometry for 6 h at a constant current density of 10 mA/cm2. Thus the results of the present study established NiFe LDH@NDCDs as an efficient electrocatalyst for the OER in alkaline medium.