Fe–Ni Layered Double Hydroxide Arrays with Homogeneous Heterostructure as Efficient Electrocatalysts for Overall Water Splitting

Abstract

Design and synthesis of highly efficient, stable, and low-cost catalysts have a crucial role in the study of electrolytic water. In this work, a novel Fe–Ni layered double hydroxide (LDH) material with homogeneous heterostructures is successfully synthesized by a two-step hydrothermal method. Compared with the ordinary Fe–Ni LDH arrays prepared by one step, this structure has a rougher surface, so it has a more extensive active area, thus providing more active sites. Due to the synergistic effect of different elements and more exposure of active sites, the catalytic effect of this material for water splitting is outstanding. The post-optimized FeNi@FeNi electrode exhibits extraordinary OER (oxygen evolution reaction) and HER (hydrogen evolution reaction) performance with OER overpotentials of 193, 231, and 306 mV and HER overpotentials of 127, 173, and 253 mV when the current density is 10, 20, and 50 mA·cm–2, respectively. The improved electrolytic water performance reveals that the design of homogeneous heterostructures is maybe an alternative route to exploit high-efficiency catalysts and promote the application of nonprecious metal catalytic materials.

In Situ Growth of 3D NiFe LDH‐POM Micro‐Flowers on Nickel Foam for Overall Water Splitting

“…Earth‐abundant transition metal layered double hydroxides (LDHs) have been recognized as promising electrocatalysts for overall water splitting in alkaline media. [ 5–8 ] Stahl and co‐workers [ 9 ] found that in NiFe LDH electrocatalysts, water oxidation occurred at reactive Fe 4+ species generated at edge, corner, or defect sites within Fe‐doped NiOOH lattice. However, their relatively inferior conductivity, sparse catalytic edge sites, and surface electronic structure and density limit the electrocatalytic performance.…”

“…As a result, the catalyst achieved a voltage of 1.88 V at the current density of 50 mV cm −2 toward overall water splitting. [ 6 ]…”

“…As a result, the catalyst achieved a voltage of 1.88 V at the current density of 50 mV cm −2 toward overall water splitting. [6] In addition, by tailoring the surface electronic structure of metal sites in NiFe LDH, the adsorption energies (ΔG) of reaction intermediates can be tuned effectively, which may lead to boost kinetics of electrocatalytic process. [16] In this regard, the element doping has demonstrated an effective way.…”

Nickel-iron layered double hydroxides for an improved Ni/Fe hybrid battery-electrolyser

“…However, in this work, OER has become an asset next to the battery functionality which makes other cation choices interesting. Iron offers the advantage of a good stability at the trivalent state 30 ; as well as a high OER catalytic behaviour when combined with Ni as Fe-NiOOH [31][32][33][34][35] . Indeed, recently NiFe-LDH has gained increasing attention in the water oxidation field and is now recognized as one of the most promising OER catalysts for alkaline media 36,37 .…”

Synergetic Engineering of High‐Oxidation‐State Cations on Phase Boundaries toward High‐Efficiency Water Splitting

“…Tremendous research efforts have been devoted to the design and development of transition metal‐based substances for water decomposition catalysis, e. g. sulfides, [17,18] carbides, [19] phosphates, [3,20,21] borides, [22] hydroxides, [23–25] metal oxides [26] and so on [27,28] . Well‐known layered double hydroxides (LDHs) such as NiFe‐LDH, [29–31] NiCo‐LDH, [32,33] NiMn‐LDH, [34] NiTi‐LDH, [35] NiV‐LDH [36,37] have also been deemed as “star materials” for many years with impressive catalytical performances due to their large surface area and the adjustable chemical composition in layered structure. Puzzlingly, NiAl LDH as a host material towards water decomposition did not inherit the excellent catalytical ability but with sluggish water‐decomposition kinetics and relatively poor electrocatalytic activity [38] .…”