Trinary Layered Double Hydroxides as High‐Performance Bifunctional Materials for Oxygen Electrocatalysis

Abstract

show superb activities than either of the parent metal catalyst, and comparable to the best noble catalysts (e.g., IrO 2 and RuO 2 ) [ 12 ] for oxygen evolution reaction (OER), which is a key component for a number of energy storage and conversion processes. [ 13 ] However, the lack of investigations on the oxygen reduction reaction (ORR) activities of LDHs greatly limits their further application in rechargeable metal-air battery and unitized regenerative fuel cell. Thus it is intriguing to evaluate the bifunctional performance of LDH-based materials in order to broadening the usages in electrochemistry.The specifi c activity of the material for the target reaction is usually highly dependent on the chemical composition and their electronic structures. [ 14,15 ] For OER, it is found that a small amount of Fe doping was effective for enhancing the OER activities of Ni hydroxides or oxides, possibly due to the enhanced structure disorder and conductivity. [ 16 ] Recently, an excellent OER performance was observed on amorphous NiCoFe oxides which were prepared by a photochemical route. [ 17 ] As to the ORR, Co and Fe ions are believed to be the active center with specifi c crystal and electronic structures. [ 18,19 ] Moreover, Co-based compounds have been widely studied recently as bifunctional materials for oxygen electrocatalysis. [ 20 ] LDHs, which offer a wide tunability of diverse metal species and ratios in the intralayer as well as a large interlayer spacing which may accelerate the ion diffusion, should be of great potential with high bifunctional performance.In this work, the ORR and OER activities of trinary NiCoFe-LDHs have been systematically investigated. It is observed that the NiCoFe-LDH showed a reasonable bifunctional performance while the sample after preoxidation treatment (denoted as O-NiCoFe-LDH) would lead to a signifi cant enhancement. This improvement was attributed to the formation of Co 3+ in the intralayer, result in the conductivity improvement of the material. To demonstrate the practical application of the LDH catalyst, the O-NiCoFe-LDH loaded on Tefl on-treated carbon fi ber paper (T-CFP) only required a potential hysteresis of ≈800 mV to achieve stable current densities of ≈20 mA cm −2 for ORR and OER for matching the current requirement of rechargeable zinc-air batteries, [ 21 ] much smaller than those of the commercial 60 wt% Pt/C and 20 wt% Ir/C catalysts. This fi rst investigation on the bifunctional performance of LDHs not Layered double hydroxides (LDHs) are a family of high-profi le layer materials with tunable metal species and interlayer spacing, and herein the LDHs are fi rst investigated as bifunctional electrocatalysts. It is found that trinary LDH containing nickel, cobalt, and iron (NiCoFe-LDH) shows a reasonable bifunctional performance, while exploiting a preoxidation treatment can signifi cantly enhance both oxygen reduction reaction and oxygen evolution reaction activity. This phenomenon is attributed to the partial conversion of Co 2+ to Co 3+ state in the pr...

Promoting charge carrier utilization by integrating layered double hydroxide nanosheet arrays with porous BiVO4 photoanode for efficient photoelectrochemical water splitting

“…In addition, the nanosheets are layer-like with a layer thickness of sub-10 nm (Fig. S2) and the interface spacing between the layers may accelerate the ion diffusion [23]. A cross-section view SEM image in Fig.…”

“…Incorporation of a third metal ion has been proposed as a strategy to improve the activity of NiFe-LDH by affecting the conductivity and the structure of the binary catalyst [23,24,59]. Thus, we select Co 2+ as a third metal ion to synthesize ternary NiFeCo-LDH anchoring on porous BiVO4 photoanode (BiVO4/NiFeCo-LDH).…”

“…However, the instability and/or competing light absorbance in the visible light region of non-noble-metal OER electrocatalysts limit their applications in photoelectrocatalysis [7]. Currently, it has been found that layered double hydroxide (LDH) materials show surprisingly high OER performance [21][22][23][24][25]. They may serve as promising OEC candidates for PEC water splitting.…”

“…In addition, the LDHs are synthesized simply and grow on substrate easily in the form of nanostructure [22]. They also offer wide tunability of diverse metal species or ratios and a large interface spacing which may accelerate the ion diffusion [23]. These features guarantee that LDHs could be of wide potential as OECs for fabricating photoanodes with highly efficient PEC performance.…”

Recent Progress on Multimetal Oxide Catalysts for the Oxygen Evolution Reaction

“…[27,64,[78][79][80][81][82][83][84][85] In particular, 3d transition metals such as Zn, Mn, Fe, and Ni have been mixed with Co for the improvement of the catalytic activity. Zou et al reported Zn-Co LDH prepared by a simple coprecipitation method as an efficient water and alcohol oxidation catalyst.…”