Oxidative dissolution of NiO in aqueous electrolyte: An impedance study

Bonomo, Matteo; Naponiello, Gaia

doi:10.1016/j.jelechem.2018.03.058

Cited by 9 publications

(10 citation statements)

References 95 publications

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“…between 0 and 0.25 V and between 0.5 and 0.7 V for Ni 2+ -> Ni3+ and Ni 3+ -> Ni 4+ reactions, respectively. A similar behaviour has been already reported for NiO when is polarized in aqueous electrolytes34 . Among the various formulations of the nanocomposites in the pristine state, the system NiO_ZrO2_2% showed the lowest RCT (2218 ), and the largest values of the capacitive terms Celectrode and CINTER.…”

supporting

confidence: 87%

Nanocomposites of Nickel Oxide and Zirconia for the Preparation of Photocathodes with Improved Performance in p-Type Dye-Sensitized Solar Cells

Bonomo

Mariani

Mura

et al. 2019

J. Electrochem. Soc.

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In p-type dye sensitized solar cells (p-DSCs) with nickel oxide (NiO) based photocathodes one of the main causes of their relatively poor photoconversion performances is the fast recombination between the photoinjected holes in the valence band of the p-type semiconductor and the reduced form of the redox shuttle (typically I-). As a matter of fact, recombination phenomena at the NiO/electrolyte interface heavily limit both photovoltage and photocurrent. Different approaches have been adopted to minimize such an unwanted process: these range from the pretreatment of the electrode surface with NaOH to the employment of passivating organic molecules (e.g. CDCA) in the sensitizing solution and/or in the electrolyte solution. The present contribution describes the implementation of the addition of zirconia (ZrO2) nanoparticles in nanostructured NiO films as antirecombination agent in p-DSCs due to the electro-inactivity of ZrO2. ZrO2 nanoparticles with diameter, Ø, of 20 nm, and NiO nanoparticles with Ø < 50 nm were dispersed together in the paste precursor for screen-printing. Different compositions of the mixture of NiO and ZrO2 nanoparticles were considered. From the combined analysis of the electrochemical and photoelectrochemical properties of different nanocomposites it was concluded that the molar ratio ZrO2/NiO had the optimal range of 2-5 % for realizing photocathodes more efficacious than sole nanostructured NiO. Among the nanocomposite photoelectrodes the one obtained from the inclusion of 2% of ZrO2 nanoparticles produced the better photoelectrochemical performance being the short-circuit current density JSC = 2.037 mA/cm 2 and the overall efficiency  = 0.088% when P1 is the sensitizer. These results show an increase up to 40% compared to the unmodified NiO electrode. The unexpectedly low efficiency of electrode with molar ratio of zirconia in nickel oxide of 5% was associated to an insufficient dye-loading on NiO, in combination to the increase of the percentage of the photoelectrochemically inert ZrO2 additive. The electrochemical impedance spectroscopy (EIS) data of the complete device under illumination confirmed that the improvement is mainly due to an increase of the recombination resistance, Rrec, ongoing from sole nanostructured NiO (Rrec = 56.3 ) to the electrode obtained from the nanocomposite with molar ratio ZrO2/NiO = 0.02 (Rrec = 70.3 ).

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supporting

confidence: 87%

Nanocomposites of Nickel Oxide and Zirconia for the Preparation of Photocathodes with Improved Performance in p-Type Dye-Sensitized Solar Cells

Bonomo

Mariani

Mura

et al. 2019

J. Electrochem. Soc.

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“…There is a slight tendency of Mo being more present in samples which have been measured in cathodic conditions for all three electrolytes, which is in accordance with the data from EDX maps (Figures S15–S20). Regarding the Ni/Fe ratio, we observe a slight decrease of Ni (from 4.75 to 3.85) after 20 h of operation, which could be attributed both to imprecision of measurement or slight dissolution [56] into the electrolyte up to equilibrium.…”

Section: Resultsmentioning

confidence: 78%

Facing Seawater Splitting Challenges by Regeneration with Ni−Mo−Fe Bifunctional Electrocatalyst for Hydrogen and Oxygen Evolution

et al. 2021

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Hydrogen, produced by water splitting, has been proposed as one of the main green energy vectors of the future if produced from renewable energy sources. However, to substitute fossil fuels, large amounts of pure water are necessary, scarce in many world regions. In this work, we fabricate efficient and earth-abundant electrodes, study the challenges of using real seawater, and propose an electrode regeneration method to face undesired salt deposition. NiÀ MoÀ Fe trimetallic electrocatalyst is deposited on non-expensive graphitic carbon felts both for hydrogen (HER) and oxygen evolution reactions (OER) in seawater and alkaline seawater. Cl À pitting and the chlorine oxidation reaction are suppressed on these substrates and alkalinized electrolyte. Precipitations on the electrodes, mainly CaCO 3 , originating from seawater-dissolved components have been studied, and a simple regeneration technique is proposed to rapidly dissolve undesired deposited CaCO 3 in acidified seawater. Under alkaline conditions, NiÀ MoÀ Fe-based catalyst is found to reconfigure, under cathodic bias, into NiÀ MoÀ Fe alloy with a cubic crystalline structure and Ni : Fe(OH) 2 redeposits whereas, under anodic bias, it is transformed into a follicular Ni: FeOOH structure. High productivities over 300 mA cm À 2 and voltages down to 1.59 V@10 mA cm À 2 for the overall water splitting reaction have been shown, and electrodes are found stable for over 24 h without decay in alkaline seawater conditions and with energy efficiency higher than 61.5 % which makes seawater splitting promising and economically feasible.

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“…A second peak centered at 1.4 V vs SHE has been attributed to the oxidation Ni(III)/Ni(IV). Bonomo et al 35 studied the dissolution of tape cast NiO electrodes in KH 2 PO 4 /K 2 HPO 4 buffer, showing the same reversible peaks as in, 34 even if at different potentials because of different pH. They attribute the two peaks to the following reactions of hydrated NiO…”

Section: Mn Oxides-mn(ii)mentioning

confidence: 99%

Corrosion Study of Cr-Oxide Ceramics Using Rotating Ring Disk Electrode

Fenini¹,

Mogensen

2019

J. Electrochem. Soc.

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Oxidative dissolution of NiO in aqueous electrolyte: An impedance study

Cited by 9 publications

References 95 publications

Nanocomposites of Nickel Oxide and Zirconia for the Preparation of Photocathodes with Improved Performance in p-Type Dye-Sensitized Solar Cells

Nanocomposites of Nickel Oxide and Zirconia for the Preparation of Photocathodes with Improved Performance in p-Type Dye-Sensitized Solar Cells

Facing Seawater Splitting Challenges by Regeneration with Ni−Mo−Fe Bifunctional Electrocatalyst for Hydrogen and Oxygen Evolution

Corrosion Study of Cr-Oxide Ceramics Using Rotating Ring Disk Electrode

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