CeO_x-Decorated NiFe-Layered Double Hydroxide for Efficient Alkaline Hydrogen Evolution by Oxygen Vacancy Engineering

Abstract

As a promising bifunctional electrocatalyst for water splitting, NiFe-layered double hydroxide (NiFe LDH) demonstrates an excellent activity toward oxygen evolution reaction (OER) in alkaline solution. However, its hydrogen evolution reaction (HER) activity is challenged owing to the poor electronic conductivity and insufficient electrochemical active sites. Therefore, a three-dimensional self-supporting metal hydroxide/oxide electrode with abundant oxygen vacancies is prepared by electrodepositing CeO nanoparticles on NiFe LDH nanosheets. According to the density functional theory calculations and experimental studies, the oxygen vacancies at the NiFe LDH/CeO interface can be introduced successfully because of the positive charges accumulation resulting from the local electron potential difference between NiFe LDH and CeO . The oxygen vacancies accelerate the electron/ion migration rates, facilitate the charge transfer, and increase the electrochemical active sites, which give rise to an efficient activity toward HER in alkaline solution. Furthermore, NF@NiFe LDH/CeO needs a lower potential of 1.51 V to drive a current density of 10 mA cm in overall water splitting and demonstrates a superior performance compared with the benchmark Pt/C and RuO, which is indicated to be a promising bifunctional electrode catalyst.

Recent Progress of Vacancy Engineering for Electrochemical Energy Conversion Related Applications

“…It is well known that layered double hydroxide (LDH)‐based nanomaterials are efficient electrocatalysts for OER, but the catalytic activities for HER are unsatisfactory due to their inferior in converting the absorbed H to hydrogen gas. [ 149 ] To overcome this challenge, Zhao and co‐workers [ 135 ] prepared CeO x nanoparticles on NiFe LDH nanosheets (NiFe LDH/CeO x ) via electrodeposition process (Figure 14c). EIS measurement demonstrated that the designed NiFe LDH/CeOx exhibited the lowest charge‐transfer resistance relative to other measured samples because of the oxygen vacancies at their interface between NiFe LDH and CeO x changed the charge distribution, local electric field and increased the charge carrier concentration.…”

“…Reproduced with permission. [ 135 ] Copyright 2018, American Chemical Society. d) Adsorption energies of H 2 O molecules on the surfaces of Ni 3 N and Ni 3 N 1 −x .…”

Three‐Dimensional Graphene‐Foam‐Supported Hierarchical Nickel Iron Phosphide Nanosheet Arrays as Efficient and Stable Bifunctional Electrocatalysts for Overall Water Splitting

“…The intermediate product of NiFe‐LDH@3DGF (Figure b) exhibit that the NiFe‐LDH nanosheets directly grow on the porous channels of graphene foam and uniformly form an intersected network. The phase information of NiFe‐LDH@3DGF can be obtained by XRD pattern (Figure S2), which corresponds to the structure of NiFe‐LDH (PDF#40‐0215) . Through the low‐temperature phosphating reaction, NiFe‐LDH was converted into phosphide NiFe‐P, without any morphological change and destruction (Figure c, d).…”

“…The phase information of NiFe-LDH@3DGF can be obtained by XRD pattern ( Figure S2), which corresponds to the structure of NiFe-LDH (PDF#40-0215). [43,44] Through the low-temperature phosphating reaction, NiFe-LDH was converted into phosphide NiFe-P, without any morphological change and destruction (Figure 2c, d). The XRD pattern of NiFe-P@3DGF shown in Figure S3 reveals that the peaks at 40.8°, 44.5°, 47.6°, 54.3°, and 54.8°are indexed to (111), (201), (210), (300), and (211) facets, very close to that of Ni 2 P (PDF#74-1385), which indicates that NiFe-P component actually can be confirmed to be the Fe doped Ni 2 P single-phase substance due to the introduction of Fe atoms, rather than multiphase structure.…”

One-step electrodeposition of cerium-doped nickel hydroxide nanosheets for effective oxygen generation

“…[21][22][23][24][25][26] Recently, several groups reported the improvement of the performance of catalysts in hydrogen and oxygen generation by doping cerium into the host catalyst or constructing a heterogeneous structure between CeO 2 and the active catalysts. [27][28][29][30][31][32][33][34] For instance, CeO 2 -cluster-doped NiO shows better performance in the OER than CeO 2 cluster surface-loaded NiO, due to promoted oxygen storage capacity and modied electronic structure of the active sites. 35 The promotion of FeOOH catalysts for OER by the integration of CeO 2 has been demonstrated due to the larger oxygen storage capacity of CeO 2 and electron interaction between CeO 2 and electrocatalysts.…”