High-valence metals improve oxygen evolution reaction performance by modulating 3d metal oxidation cycle energetics

Zhang, Bo; Wang, Lie; Cao, Zhen; Kozlov, Sergey M.; Arquer, F. Pelayo Garcı́a de; Dinh, Cao-Thang; Li, Jun; Wang, Ziyun; Zheng, Xueli; Zhang, Longsheng; Wen, Yunzhou; Voznyy, Oleksandr; Comin, Riccardo; Luna, Phil De; Regier, Tom; Bi, Wenli; Ercan, E.; Pao, Chih‐Wen; Zheng, Lirong; Hu, Yongfeng; Ji, Yujin; Li, Youyong; Zhang, Ye; Cavallo, Luigi; Peng, Huisheng; Sargent, Edward H.

doi:10.1038/s41929-020-00525-6

Cited by 517 publications

(370 citation statements)

References 31 publications

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“…When the etching depth increases, the signals of Ni 2+ gradually weaken and finally disappear, only metallic Ni signals exist (Figure 2c). The Fe 2p profile shows a similar trend that the signals of Fe 3+ , which supposedly come from Fe‐doped Ni(OH) 2 [short as NiFe(OH) 2 ], [ 23 ] gradually weaken and those of the metallic Fe (peaks at 706.6 and 719.8 eV) keep increasing from the surface to the interior of activated NiFe‐ONCAs. [ 14a ] The broad peak at around 711.5 eV can be attributed to the Auger peak of Auger Ni LMM.…”

Section: Figurementioning

confidence: 69%

Tip‐Enhanced Electric Field: A New Mechanism Promoting Mass Transfer in Oxygen Evolution Reactions

et al. 2021

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The slow kinetics of oxygen evolution reaction (OER) causes high power consumption for electrochemical water splitting. Various strategies have been attempted to accelerate the OER rate, but there are few studies on regulating the transport of reactants especially under large current densities when the mass transfer factor dominates the evolution reactions. Herein, NixFe1–x alloy nanocones arrays (with ≈2 nm surface NiO/NiFe(OH)2 layer) are adopted to boost the transport of reactants. Finite element analysis suggests that the high‐curvature tips can enhance the local electric field, which induces an order of magnitude higher concentration of hydroxide ions (OH−) at the active sites and promotes intrinsic OER activity by 67% at 1.5 V. Experimental results show that a fabricated NiFe nanocone array electrode, with optimized alloy composition, has a small overpotential of 190 mV at 10 mA cm−2 and 255 mV at 500 mA cm−2. When calibrated by electrochemical surface area, the nanocones electrode outperforms the state‐of‐the‐art OER electrocatalysts. The positive effect of the tip‐enhanced local electric field in promoting mass transfer is also confirmed by comparing samples with different tip curvature radii. It is suggested that this local field enhanced OER kinetics is a generic effect to other OER catalysts.

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Section: Figurementioning

confidence: 69%

Tip‐Enhanced Electric Field: A New Mechanism Promoting Mass Transfer in Oxygen Evolution Reactions

et al. 2021

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“…Notably, recent research has reported that Mo 5+ and W 6+ can also improve the OER activity of NiFe-LDHs by lowering the valence state of Ni and Fe prior to the OER. 154 On the other hand, redox inert homovalent metal cations such as Mg 2+ and Ca 2+ can reduce the intrinsic OER activity of NiFe-LDHs due to the decreased number of available active sites, although some recent reports show that doping Mg 2+ and Ca 2+ into NiFe-LDHs can improve the OER activity in neutral medium by enhancing the water dissociation process.…”

Section: Modulation Of the Compositions Of Ldh Nanosheetsmentioning

confidence: 99%

Layered double hydroxide-based electrocatalysts for the oxygen evolution reaction: identification and tailoring of active sites, and superaerophobic nanoarray electrode assembly

et al. 2021

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“…Fe 2p XPS unveils partial Fe 3+ transfer to Fe 2+ , which promotes the cycling of Ni and Co between the 2+ and 3+ oxidation states. [ 23 ] As for Cr XPS spectra, the (CrFeCoNi) 97 O 3 and (CrFeCoNiMn) 97 O 3 O‐HEA are displayed in Figure 4b and Figure S16, Supporting Information. We find that Cr exhibits different valence states in the (CrFeCoNi) 97 O 3 O‐HEA by fitting the peak, that is, Cr 0 (573.34 eV), Cr 3+ (576.14 eV), and Cr 6+ (578.05 eV), respectively.…”

Section: Resultsmentioning

confidence: 99%

“…Nevertheless, other systems exhibit the best catalytic activity with oxygen content of 1 at% and 2 at%, which might be due to the different oxygen affinity [ 12c,22 ] and the interaction between atoms. [ 14a,23 ] When the current density rises to 100 mA cm −2 , the overpotential of 255 mV can be obtained indicating it has a potential in practical application, as displayed in Figure S19c, Supporting Information.…”

Section: Resultsmentioning

confidence: 99%

Engineering Microdomains of Oxides in High‐Entropy Alloy Electrodes toward Efficient Oxygen Evolution

et al. 2021

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One important goal of the current electrocatalysis is to develop integrated electrodes from the atomic level design to multilevel structural engineering in simple ways and low prices. Here, a series of oxygen micro‐alloyed high‐entropy alloys (O‐HEAs) is developed via a metallurgy approach. A (CrFeCoNi)97O3 bulk O‐HEA shows exceptional electrocatalytic performance for the oxygen evolution reaction (OER), reaching an overpotential as low as 196 mV and a Tafel slope of 29 mV dec−1, and with stability longer than 120 h in 1 m KOH solution at a current density of 10 mA cm−2. It is shown that the enhanced OER performance can be attributed to the formation of island‐like Cr2O3 microdomains, the leaching of Cr3+ ions, and structural amorphization at the interfaces of the domains. These findings offer a technological‐orientated strategy to integrated electrodes.

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High-valence metals improve oxygen evolution reaction performance by modulating 3d metal oxidation cycle energetics

Cited by 517 publications

References 31 publications

Tip‐Enhanced Electric Field: A New Mechanism Promoting Mass Transfer in Oxygen Evolution Reactions

Tip‐Enhanced Electric Field: A New Mechanism Promoting Mass Transfer in Oxygen Evolution Reactions

Layered double hydroxide-based electrocatalysts for the oxygen evolution reaction: identification and tailoring of active sites, and superaerophobic nanoarray electrode assembly

Engineering Microdomains of Oxides in High‐Entropy Alloy Electrodes toward Efficient Oxygen Evolution

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