Progress in understanding hematite electrochemistry through computational modeling

Snir, Nadav; Yatom, Natav; Toroker, Maytal Caspary

doi:10.1016/j.commatsci.2019.01.001

Cited by 16 publications

(9 citation statements)

References 34 publications

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“…9) from p-type to n-type. This is because the concentration of electrons is not enough to compensate the majority holes in the NiO lattice [28][29][30] , as evidenced by the nearly same work function before and after C doping ( Supplementary Fig. 10).…”

Section: Synthesis and Structural Characterization Of C-doped Niomentioning

confidence: 99%

Carbon doping switching on the hydrogen adsorption activity of NiO for hydrogen evolution reaction

et al. 2020

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Hydrogen evolution reaction (HER) is more sluggish in alkaline than in acidic media because of the additional energy required for water dissociation. Numerous catalysts, including NiO, that offer active sites for water dissociation have been extensively investigated. Yet, the overall HER performance of NiO is still limited by lacking favorable H adsorption sites. Here we show a strategy to activate NiO through carbon doping, which creates under-coordinated Ni sites favorable for H adsorption. DFT calculations reveal that carbon dopant decreases the energy barrier of Heyrovsky step from 1.17 eV to 0.81 eV, suggesting the carbon also serves as a hot-spot for the dissociation of water molecules in water-alkali HER. As a result, the carbon doped NiO catalyst achieves an ultralow overpotential of 27 mV at 10 mA cm −2 , and a low Tafel slope of 36 mV dec −1 , representing the best performance among the state-of-theart NiO catalysts.

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Section: Synthesis and Structural Characterization Of C-doped Niomentioning

confidence: 99%

Carbon doping switching on the hydrogen adsorption activity of NiO for hydrogen evolution reaction

et al. 2020

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“…These results suggest that the slowest step in the POER on hematite is probably step 10a in scheme 2. As noted in section 4, Snir et al [30] find that the DOS for the Fe (IV)=O state is located around 0.4 eV above the valence band of hematite, and they suggest that the observed absorption in the visible region is associated with excitation from this state to the conduction band.…”

Section: Reaction Mechanisms and Reaction Ordersmentioning

confidence: 81%

“…The molecular identity of species such as *O formed in reaction 9a can be confirmed by suitable in situ spectroscopic methods, as discussed later in this review, or suggested by DFT calculations. In the case of hematite, for example, Snir et al [30] have used DFT + U to show that the *O intermediate corresponds to a Fe(IV)=O state located 0.4 eV above the valence band.…”

Section: The Oxygen Evolution Reaction At Photoanodesmentioning

confidence: 99%

Fundamental aspects of photoelectrochemical water splitting at semiconductor electrodes

Peter

2021

Current Opinion in Green and Sustainable Chemistry

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“…To obtain the activation energy ( E a ) with the Arrhenius equation, we need to measure reaction rate constants ( k ) first. In the alkaline OER, the main reaction is given by eq . , Thus, the reaction rates can be expressed as oxygen gas production in a unit of time, as a function of hydroxide ion concentration (eq ). The production rate of oxygen gas is directly proportional to the quantity of current generated through the number of electron transfers per unit area (eq ) where i / A is the current density obtained from the LSV curve at different applied potentials (V vs. RHE), n is the number of electron transfers during the OER ( n = 4), F is the Faraday constant (96485 C mol –1 ), and x is the order of the catalytic reaction.…”

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confidence: 99%

Activation Energy Assessing Potential-Dependent Activities and Site Reconstruction for Oxygen Evolution

et al. 2022

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We demonstrated the activation energy approach to evaluate oxygen evolution performance and to probe active site reconstruction at different potentials. Activation energies are acquired following the Arrhenius equation by monitoring the current densities under varied hydroxide concentrations and temperatures. Our complex oxide electrocatalysts (Ag-and Ce-bidoped iron manganese oxyhydroxide) exhibit a much smaller activation energy of 19.12 kJ mol −1 in comparison to FeMnOH (60.01 kJ mol −1 ) at 1.7 V. The higher numbers of doped metal cations show smaller activation energy values corresponding to the higher activities, yet site reconstruction is less likely to occur. Through operando Raman studies, site reconstruction may not be absolutely required to reach a high-performance OER, in contrast to the general recognition. By knowing the potential-dependent activation energy, a quantitative OER activity comparison among reconstructed sites is possible. A substrate with a low background current is useful to experimentally acquire iR-corrected activation energies over a wide potential window.

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Progress in understanding hematite electrochemistry through computational modeling

Cited by 16 publications

References 34 publications

Carbon doping switching on the hydrogen adsorption activity of NiO for hydrogen evolution reaction

Carbon doping switching on the hydrogen adsorption activity of NiO for hydrogen evolution reaction

Fundamental aspects of photoelectrochemical water splitting at semiconductor electrodes

Activation Energy Assessing Potential-Dependent Activities and Site Reconstruction for Oxygen Evolution

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