Robust electrolytic oxygen evolution at nanostructured NiFe LDH@ in-situ functionalized graphite felt

Abstract

NiFe layered double hydroxide (LDH) is among the most effective electrocatalysts for oxygen evolution reaction (OER). Tailor-designed NiFe LDH with high electronic conductivity assists in facile hydrogen production with marked energy-saving. Graphite felt (GF), a 3-D porous substrate with excellent conductivity is used herein. However, its low hydrophilicity calls for pretreatment. Herein, the potential strength of electrochemistry is applied to enhance the hydrophilicity of GF surface during the deposition of homogenous uniform distributed NiFe LDH electrocatalyst. GF is sequentially modified by sweeping the potential from the oxidative to the reductive region in a solution containing 100 mM NiSO4 and 30 mM FeCl3. Carbon structure flaws are introduced at the positive potential region. whereas during the negative potential scan, hydrogen evolution occurs with simultaneous uniform and homogeneous deposition of NiFe LDH. SEM, HR-TEM, mapping EDX, XPS, XRD, and contact angle measurements are utilized to reveal the features of the functionalized GF with NiFe LDH deposits. Furthermore, FeOOH/GF and Ni(OH)2/GF electrodes are prepared to highlight the advantages of the binary NiFe LDH/GF electrode toward the OER. Interestingly, the NiFe LDH/GF enhances the OER in an alkaline medium by throwing up a low overpotential of 273 mV to support a current density of 10 mA cm−2 alongside a Tafel slope of 48.5 mV dec−1. Furthermore, the NiFe LDH shows marked stability for 24 h of ongoing electrolysis. Therefore, the designed catalyst can be worked as an efficient anode for water electrolysis.