Facile synthesis of nanometer-sized NiFe layered double hydroxide/nitrogen-doped graphite foam hybrids for enhanced electrocatalytic oxygen evolution reactions

One‐Step Synthesis of NiFe Layered Double Hydroxide Nanosheet Array/N‐Doped Graphite Foam Electrodes for Oxygen Evolution Reactions

“…With further addition of urea, NH 3 was not consumed off after hydrolysis process, thus allowing considerable N doping. As a result, N element was observed in NiFe LDH/NGF‐4, and the ratio of Ni/Fe was calculated to be 3.95, which is consistent with the raw solution and in the optimal composition range for NiFe LDH as OER catalysts . In addition, NiFe LDH/NGF‐4 exhibited relatively uniform nanosheet arrays during the equilibrium of LDH sheets precipitation/dissolution process due to the strong interaction between uniformly dispersed N dopants and LDH sheets.…”

“…LDH structure by excessive urea content shows negligible Ni 2+ /Ni 3+ redox peak and much reduced catalytic activity (see NiFe LDH/NGF‐10 and 20). We also examined the influence of Ni/Fe ratio on the OER activity, and adopted an optimized Ni/Fe ratio of 4 : 1 (Figure S11), in consistence with the previous reports …”

“…Obviously, the NiFe LDH/NGF‐4 exhibits the smallest diameter, which is calculated to be 0.24 Ω cm 2 (0.26, 0.29, 0.41, 0.47 Ω cm 2 for NiFe LDH/NGF‐1, 2, 10, and 20, respectively), implying high charge transport efficiency. This enhanced kinetic should be ascribed to the strong interaction between N dopants and NiFe LDH nanosheets, the highly conductive self‐supporting substrate without other additives, and the accelerated diffusion of electrolyte and gas bubbles …”

“…To enhance the diffusion of liquid reactants and gas products, directly fabricating the active species with three dimensional (3D) architecture on free‐standing conductive substrates as integrated electrodes has been explored . Concomitantly, the active sites are adequately exposed by constructing 3D nanostructures; the electrochemically active surface area, penetration of electrolyte, and transportation of electron are also increased by the binder‐free characteristic . Considering these aforementioned factors, it would be of substantial significance to develop a facile and efficient strategy for loading NiFe LDHs with 3D architectures on a free‐standing nitrogen‐doped substrate for OER.…”

“…[39][40][41][42] Concomitantly, the active sites are adequately exposed by constructing 3D nanostructures; [43][44][45][46] the electrochemically active surface area, penetration of electrolyte, and transportation of electron are also increased by the binder-free characteristic. [47] Considering these aforementioned factors, it would be of substantial significance to develop a facile and efficient strategy for loading NiFe LDHs with 3D architectures on a free-standing nitrogen-doped substrate for OER.…”