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Two-dimensional transition metal hydroxides are greatly limited in the application of the electrocatalytic oxygen evolution reaction (OER) due to its large and inert basal planes. Herein, we report a one-step in situ etching hydrothermal method to construct Co(OH)2 and Ni(OH)2 heterostructure nanomaterials, successfully activating the basal plane of Co(OH)2. The abundant lattice strains that appear at heterogeneous interfaces cause a downshift of the d-band center of Co in Co(OH)2 and promote the desorption of oxygen during the OER process, which accelerates reaction kinetics of the OER and improves catalytic activity effectively. Furthermore, the electron interaction at the Co(OH)2/Ni(OH)2 interfaces leads to charge polarization, which will regulate the adsorption and dissociation of H2O molecules and enhances mass and electron transfer. Owing to the above advantages of Co(OH)2/Ni(OH)2 interfaces, the as-prepared composite catalysts show an excellent OER catalytic performance with a low overpotential of only about 270 mV at 20 mA cm−2, maintaining long-term catalytic stability for more than 24 h at 20 mA cm−2. [ABSTRACT FROM AUTHOR]

The integration of Fe dopant and interfacial FeOOH into Ni-MOFs [Fe-doped-(Ni-MOFs)/FeOOH] to construct Fe-O-Ni-O-Fe bonding is demonstrated and the origin of remarkable electrocatalytic performance of Ni-MOFs is elucidated. X-ray absorption/photoelectron spectroscopy and theoretical calculation results indicate that Fe-O-Ni-O-Fe bonding can facilitate the distorted coordinated structure of the Ni site with a short nickel-oxygen bond and low coordination number, and can promote the redistribution of Ni/Fe charge density to efficiently regulate the adsorption behavior of key intermediates with a near-optimal d-band center. Here the Fe-doped-(Ni-MOFs)/FeOOH with interfacial Fe-O-Ni-O-Fe bonding shows superior catalytic performance for OER with a low overpotential of 210 mV at 15 mA cm -2 and excellent stability with ≈3 % attenuation after a 120 h cycle test. This study provides a novel strategy to design high-performance Ni/Fe-based electrocatalysts for OER in alkaline media., (© 2022 Wiley-VCH GmbH.)

The intrinsic activity of NiFe layer double hydroxides (LDHs) for the oxygen evolution reaction (OER) suffers from its predominantly exposed (003) basal plane, which is thought to have poor activity. Herein, we construct a hierarchal structure of NiFe LDH nanosheet-arrays-on-microplates (NiFe NSAs-MPs) to elevate the electrocatalytic activity of NiFe LDHs for the OER by exposing a high-activity plane, such as the (012) edge plane. It is surprising that the NiFe NSAs-MPs show activity of 100 mA cm -2 at an overpotential ( η ) of 250 mV, which is five times higher than that of (003) plane-dominated NiFe LDH microsheet arrays (NiFe MSAs) at the same η , representing the excellent electrocatalytic activity for the OER in alkaline media. Besides, we analyzed the OER activities of the (003) basal plane and the (012) and (110) edge planes of NiFe LDHs by density functional theory with on-site Coulomb interactions (DFT+U), and the calculation results indicated that the (012) edge plane exhibits the best catalytic performance among the various crystal planes because of the oxygen coordination of the Fe site, which is responsible for the high catalytic activity of NiFe NSAs-MPs., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Porous CoFe 2 O 4 /C NRAs supported on nickel foam@NC (denoted as NF@NC-CoFe 2 O 4 /C NRAs) are directly fabricated by the carbonization of bimetal-organic framework NRAs grown on NF@poly-aniline(PANI), and they exhibit high electrocatalytic activity, low overpotential, and high stability for the oxygen evolution reaction in alkaline media., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)