Highly Active Trimetallic NiFeCr Layered Double Hydroxide Electrocatalysts for Oxygen Evolution Reaction

Abstract

rechargeable metal-air batteries. [1,2] This reaction demands efficient electrocatalysts that can accelerate the reaction rate, lower the overpotential, and remain stable over time. Currently, noble-metal-based compounds such as IrO 2 and RuO 2 provide good OER performance under alkaline conditions, but their large-scale application is restricted by their scarcity and high cost. [3] Accordingly, much research effort has been devoted to the development of high-performance earth-abundant OER electrocatalysts based on transition-metal elements, usually in the form of metal oxides or metal (oxy)hydroxides, that are inexpensive and stable upon prolonged exposure under oxidizing conditions. [4][5][6][7] In addition to the synergistic effects of transition metals and electrical conductivity, the intrinsic activities of these transition metal oxide or (oxy)hydroxide OER catalysts are closely connected to the number of 3d electrons of the metals; the surface transition-metal ions exhibited e g orbitals which could bond with surfaceanion adsorbates and then influence the binding of oxygenic intermediates. [8,9] The binding strength of these intermediates is thought to dictate catalytic activity. [10] Identifying the relationship between OER activity and the catalyst electronic structure can provide a simple rationale for gaining mechanistic insights and finding new design strategies for the earth-abundant OER catalysts.Among various transition metal-based OER catalysts, metal layered double hydroxides (LDHs) and oxyhydroxides have attracted much attention because of their abundance in the earth's crust and their considerable catalytic activity. [5,6,[11][12][13][14][15][16][17][18][19][20][21] NiFe LDH and more generally NiFe (oxy)hydroxides have emerged as the most active OER catalyst compared to other bimetallic earth-abundant LDHs under basic conditions, [6,15,17,22] and several studies have been directed at understanding the role of Fe in increasing the OER intrinsic activity of NiFe-containing (oxy) hydroxide materials. [23] Boettcher and co-workers demonstrated that Fe incorporation into NiOOH lattice enhances the electronic conductivity in the film and Fe exerts a partial-chargetransfer activation effect on Ni centers throughout the catalyst film, but the enhanced catalytic efficiency cannot be completely explained. [17] To better understand the role of Fe, they further studied other incorporated metal cations (Mn, Ti, Ce, Fe, and La) in NiO x H y , finding that only Fe permanently increases the OER The development of efficient and robust earth-abundant electrocatalysts for the oxygen evolution reaction (OER) is an ongoing challenge. Here, a novel and stable trimetallic NiFeCr layered double hydroxide (LDH) electrocatalyst for improving OER kinetics is rationally designed and synthesized. Electrochemical testing of a series of trimetallic NiFeCr LDH materials at similar catalyst loading and electrochemical surface area shows that the molar ratio Ni:Fe:Cr = 6:2:1 exhibits the best intrinsic OER catalytic activity ...

Large‐Scale, Bottom‐Up Synthesis of Binary Metal–Organic Framework Nanosheets for Efficient Water Oxidation

“…Thedouble layer capacitance (C dl ) values were obtained by measuring the change of current within apotential period without the Faradaic process,which can be represented by the plots of Dj = (ja-jc)/2 at 1.0744 V vs.RHE against the scan rate (Figure 3b). [28] TheN yquist plots revealed that the semicircular diameter of Ni-Fe-MOF NSs was smaller than that of XPS was carried out to understand the effect of mixed metals on OER catalysis.C ompared with the Ni-MOF NSs, the peaks of Ni 2p 3/2 and Ni 2p 1/2 in the high-resolution Ni 2p spectrum of the Ni-Fe-MOF NSs shifted to as lightly higher binding energy (a shift of approximately 0.3 eV), indicating amodified local electronic structure of Ni (Figure 3d). [28] TheN yquist plots revealed that the semicircular diameter of Ni-Fe-MOF NSs was smaller than that of XPS was carried out to understand the effect of mixed metals on OER catalysis.C ompared with the Ni-MOF NSs, the peaks of Ni 2p 3/2 and Ni 2p 1/2 in the high-resolution Ni 2p spectrum of the Ni-Fe-MOF NSs shifted to as lightly higher binding energy (a shift of approximately 0.3 eV), indicating amodified local electronic structure of Ni (Figure 3d).…”

Towards Long‐Term Photostability of Nickel Hydroxide/BiVO4 Photoanodes for Oxygen Evolution Catalysts via In Situ Catalyst Tuning

“…X‐ray diffraction (XRD) patterns of V‐NiOOH displayed a weak intensity of peaks compared to NiOOH (Figure c), implying that the defects or amorphous phase were existed in OEC after treatment. X‐band electron paramagnetic resonance (EPR) spectroscopy of V‐NiOOH showed a stronger g signal intensity than NiOOH (Figure f), indicative of the modulating effect of plasma etching on the electronic structure of NiOOH …”

Tungsten‐Doped CoP Nanoneedle Arrays Grown on Carbon Cloth as Efficient Bifunctional Electrocatalysts for Overall Water Splitting

“…Non-noble metal phosphides, [5] chalcogenides, [6] carbides, [7] nitrides [8] have been explored as electrocatalysts for HER in acidic media and metal oxides [9] or hydroxide [10] are widely investigated as OER catalysts in basic media. Although these HER and OER electrocatalysts often function well in acidic or alkaline solutions, respectively, it is difficult to couple HER and OER catalysts in an integrated electrolyzer in the same electrolyte with good overall water splitting performance because of the incompatibility between stability and activity.…”