Bi‐Functional Fe₃O₄/Au/CoFe‐LDH Sandwich‐Structured Electrocatalyst for Asymmetrical Electrolyzer with Low Operation Voltage

Abstract

The reduction of the overall electrolysis potential to produce hydrogen is a critical target for fabricating applicable hydrogen evolution cells. Sandwich‐structured Fe3O4/Au/CoFe‐LDH is synthesized via a spontaneous galvanic displacement reaction. A series of structural characterizations indicate the successful synthesis of sandwich‐structured Fe3O4/Au/CoFe‐LDH electrocatalyst. The trace amount of Au laying between Fe3O4 and CoFe‐LDH significantly improves the intrinsic conductivity and catalytic activity of the composite catalyst. In‐depth investigations indicate that Fe3O4 and CoFe‐LDH are responsible for the electrocatalytic hydrogen evolution reaction (HER) whereas Au is responsible for the electrocatalytic glucose oxidation (GOR). The electrocatalytic tests indicate Fe3O4/Au/CoFe‐LDH offers excellent electrocatalytic activity and stability for both HER and GOR, even at high current density (i.e., 1000 mA cm−2). Further electrochemistry examinations in a two‐compartment cell with a two‐electrode configuration show that Fe3O4/Au/CoFe‐LDH can significantly reduce the overall potential for this asymmetrical cell, with only 0.48 and 0.89 V required to achieve 10 mA cm−2 current density with and without iR‐compensation, which is the lowest overall potential requirement ever reported. The design and synthesis of Fe3O4/Au/CoFe‐LDH pave a new way to electrochemically produce hydrogen and gluconate under extremely low cell voltage, which can readily match with a variety of solar cells.

CoFe-Layered Double Hydroxide Coupled with Pd Particles for Electrocatalytic Ethanol Oxidation

“…The results indicated that Pd transferred electrons to Co and Fe in the LDH support, which was evidence of the strong interaction of Pd nanoparticles with the LDH substrate. Besides, four distinct components could be seen in the O 1s spectra for Co 1 Fe 3 –LDH/NF and Pd/Co 1 Fe 3 –LDH/NF (Figure d), including the peak located at around 530.2 eV corresponding to oxygen vacancy (V O ), the peak located at around 530.9 eV appertaining to M–O (M = Pd, Co, Fe), the peak at around 531.6 eV belonging to absorbed H 2 O, and the peak at 532.8 eV corresponding to CO 3 2– , which well matched with those reported LDH materials containing interlayer carbonate anions . The relative area ratios of V O to M–O to H 2 O were about 0.21:1.16:1 for Pd/Co 1 Fe 3 –LDH/NF and 0.35:0.92:1 for Co 1 Fe 3 –LDH/NF, proving that Pd nanoparticles anchored on Co 1 Fe 3 –LDH via O atoms and V O sites.…”

“…Pd/Co 1 Fe 3 –LDH/NF and Co 1 Fe 3 –LDH/NF both detected two regions of Co 2p 3/2 and Co 2p 1/2 with their corresponding satellite peaks (Figure b). , In addition, the relative area ratios of Co 2+ to Co 3+ were about 1:0.54 for Pd/Co 1 Fe 3 –LDH/NF and 1:1.08 for Co 1 Fe 3 –LDH/NF, suggesting the reduction of Co species after loading Pd onto Co 1 Fe 3 –LDH/NF. Similarly, the Fe 2p spectra showed two regions of Fe 2p 3/2 and Fe 2p 1/2 with their corresponding satellite peaks from both Pd/Co 1 Fe 3 –LDH/NF and Co 1 Fe 3 –LDH/NF (Figure c), , and the relative area ratios of Fe 2+ to Fe 3+ were about 1:0.67 for Pd/Co 1 Fe 3 –LDH/NF and 1:0.79 for Co 1 Fe 3 –LDH/NF, suggesting the slight reduction of Fe species after loading Pd nanoparticles onto Co 1 Fe 3 –LDH/NF. The results indicated that Pd transferred electrons to Co and Fe in the LDH support, which was evidence of the strong interaction of Pd nanoparticles with the LDH substrate.…”

Surface charge modulation enhanced high stability of gold oxidation intermediates for electrochemical glucose sensors

“…As illustrated in Fig. 5(e), in the absence of glucose, the redox peak of Ni appears for Au300 Ni Foam, while a small oxidation peak, probably corresponding to Au → AuOH, appears near 0 V. 41 The shapes of CV curves change significantly when glucose is present, with all three samples showing sharp oxidation peaks in negative scans. The order of the magnitude of the positions of the oxidation peaks for the three samples is Au300 Cu Foam < Au300 Ni Foam < Au300 Fe Foam.…”

“…According to previous literature, this pair of peaks is the redox peak of Au 0 with Au 1+ (ref. 41). Fig.…”

Recent Progress on Transition Metal Based Layered Double Hydroxides Tailored for Oxygen Electrode Reactions

“…Such a Janus MnO 2 -NiFe air electrode endowed the zinc-air battery with better cycling stability and energy efficiency than the bare MnO 2 and NiFe-LDHs electrodes, as illustrated in Figure 14D. In another interesting example, a bifunctional electrocatalyst: Fe 3 O 4 /Au/CoFe-LDH with sandwich structured, was used for the hydrogen evolution reaction and the electrocatalytic glucose oxidation reaction (GOR) [219]. The combination of structural characterizations with electrochemical characterizations revealed that Fe 3 O 4 and CoFe-LDHs played key roles in catalyzing the HER, whereas metallic Au was responsible for the GOR, Figure 14E.…”