NiFe-Layered Double Hydroxide Synchronously Activated by Heterojunctions and Vacancies for the Oxygen Evolution Reaction

Abstract

The development of earth-abundant transition-metalbased electrocatalysts with bifunctional properties (oxygen evolution reaction (OER) and hydrogen evolution reaction (HER)) is crucial to commercial hydrogen production. In this work, layered double hydroxide (LDH)-zinc oxide (ZnO) heterostructures and oxygen vacancies are constructed synchronously by plasma magnetron sputtering of NiFe-LDH. Using the optimal conditions, ZnO nanoparticles are uniformly distributed on the NiFe-LDH nanoflowers, which are prepared uniformly on the three-dimensional porous Ni foam. In the LDH-ZnO heterostructures and oxygen vacancies, electrons are depleted at the Ni cations on the NiFe-LDH surface and the active sites change from Fe cations to Ni cations during OER. Our theoretical assessment confirms the change of active sites after the deposition of ZnO and reveals the chargetransfer mechanism. Owing to the significant improvement in the OER dynamics, overall water splitting can be achieved at only 1.603 V in 1 M KOH when the Ni/LDH-ZnO and Ni/LDH are used as the anode and cathode, respectively. The work reveals a novel design of self-supported catalytic electrodes for efficient water splitting and also provides insights into the surface modification of catalytic materials.

3D-printed NiFe-layered double hydroxide pyramid electrodes for enhanced electrocatalytic oxygen evolution reaction

“…S8 and Table S1 ). The XPS peak position of Ni 2p and Fe 2p showed slightly positive change after durability test, which is due to the phase transformation of the catalyst surface into oxyhydroxide in a strong oxidizing environment 48 , 49 .…”

Super‐Stable Mineralization of Ni2+ Ions from Wastewater using CaFe Layered Double Hydroxide

“…A lattice fringe spacing of 0.26 nm for NiCaFe‐LDH‐30, corresponding to the (012) facet of the NiFe‐LDH, can be observed (Figure 3f). [ 14 ] Based on XRD, TEM, and HRTEM images, we preliminarily speculated that the CaFe‐LDH was transformed to NiCaFe‐LDH with isomorphous partial substitution of Ca 2+ by Ni 2+ in the LDH structure.…”

“…A lattice fringe spacing of 0.26 nm for NiCaFe-LDH-30, corresponding to the (012) facet of the NiFe-LDH, can be observed (Figure 3f). [14] Based on XRD, TEM, and HRTEM images, we preliminarily speculated that the CaFe-LDH was transformed to NiCaFe-LDH with isomorphous partial substitution of Ca 2+ by Ni 2+ in the LDH structure. In order to study the fine structure of a series of precipitates (NiCaFe-LDH-0.5, NiCaFe-LDH-5, and NiCaFe-LDH-30) and verify the coordination structure of Ni 2+ ions, X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) were performed.…”

Porous FeP supported on 3D nitrogen-doped carbon fibers as efficient electrocatalysts for wide-pH hydrogen evolution

“…The TOF was derived from CV curves at a scanning rate of 50 mV s À1 in 1.0 M PBS (pH ¼ 7) buffer solution and was calculated by the formula (3) and (4), 37,38 where, n is active site density, S is the integral area obtained from CV curves, F is Faradic constant, and J is the current density in the LSV plots, m is scanning rate of 50 mV s À1 .…”