Towards outstanding performance of direct urea fuel cells through optimization of anode catalyst layer and operating conditions

Kim, Ok-Hee; Choi, Hee Ji; Kang, Sun Kil; Jang, Ga Young; Karuppannan, Mohanraju; Park, Ji Eun; Sung, Yung‐Eun; Kwon, Oh Joong; Cho, Yong‐Hun

doi:10.1016/j.jelechem.2022.116661

Cited by 9 publications

(9 citation statements)

References 34 publications

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“…An excess of ferrous salt was introduced into a suspension of NiOOH/Ni(OH) 2 particles. After reaction, the excess of ferrous salt was titrated by an acidic solution of potassium dichromate in accordance with Equations ( 8) and (9).…”

Section: Characterizationmentioning

confidence: 99%

“…1 Containing urea (40% wt., 2 at around 0.33 mol L À1 ), urine constitutes an important source of nitrogen, accounting for nearly 75% of the nitrogen in watercourses. 3 Electrochemical oxidation of urea is nowadays studied for meeting various targets, such as electrolyzers [4][5][6][7] (producing H 2 as an energy carrier), energy production by urea fuel cells, [8][9][10][11][12][13] or the development of advanced electrode materials. [14][15][16][17] Recent investigations 18,19 have claimed that low-cost electrode materials could be used in alkaline media for efficient urea electrooxidation (UEO), thus opening promising perspectives for UEO implementation on an industrial scale.…”

Section: Introductionmentioning

confidence: 99%

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Indirect urea electrooxidation by nickel(III) in alkaline medium: From kinetic and mechanism to reactor modeling

et al. 2023

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This study consists in the determination of two kinetic laws of urea oxidation (UO) and electrooxidation (UEO) in alkaline media on nickel(III). Two kinds of active sites were examined, the first one derived from a Ni(OH)2 powder and the second from a massive nickel electrode. Partial orders of nickel(III) (two for UO and five UEO) enable to conclude about (i) the urea adsorption on two nickel(III) sites and (ii) that a multistep oxidation of urea occurs involving five nickel(III) site electroregenerations. A multipathway mechanism is also proposed to explain UEO facilitated by the nickel(III)/nickel(II) mediation system, and to predict the by‐products' formation previously identified (). At last, a model combining the UEO kinetic law previously established, with diffusive and convective transport phenomena was developed. A consistent correlation (maximum deviation of 6%) between laboratory electrolysis results with the model' predictions was obtained under different operating conditions, enabling the validation of this model.

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Section: Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Indirect urea electrooxidation by nickel(III) in alkaline medium: From kinetic and mechanism to reactor modeling

et al. 2023

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“…After reaction, the excess of ferrous salt was titrated by an acidic solution of potassium dichromate in accordance with Eqs. ( 8)- ( 9 ).…”

Section: Characterizationmentioning

confidence: 99%

“…2 , at around 0.33 mol.L -1 ), urine constitutes an important source of nitrogen, accounting for nearly 75 % of the nitrogen in watercourses 3 . The urea electrochemical oxidation is nowadays studied for meeting various targets, such as electrolyzers [4][5][6][7] (producing H2 as energy carrier), energy production by urea fuel cells [8][9][10][11][12][13] , or advanced electrode materials development [14][15][16][17] . Recent investigations 18,19 have claimed that low-cost electrode materials could be used in alkaline media for efficient urea electro-oxidation (UEO), thus opening promising perspectives for UEO implementation at industrial scale.…”

Section: Introductionmentioning

confidence: 99%

“…! ] ..0 × [OH ( ] ..S × (S -)-1<,PW-)9 ( Proposed mechanism for the urea complete electrooxidation Based on the current state-of-art, Figure4-a-b propose an overall mechanism for urea degradation involving electrochemically generated nickel(III) sites. The reaction scheme is composed of different pathways leading to the formation of by-products previously identified in the liquid phase27 .The urea degradation mechanism from electrogenerated nickel(III) site can be classified into the nucleophilic oxidation reaction class38,39 (as for the methanol oxidation on nickel(III)40 ), involving two pathways: successive (i) electrogenerated Ni(OH)2 catalyst dehydrogenation reaction followed by (ii) a spontaneous nucleophilic dehydrogenation reaction.…”

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confidence: 99%

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Urea indirect electrooxidation by nickel(III) in alkaline medium: from kinetics and mechanisms to reactor modeling

Hopsort

Latapie²,

Serrano

et al. 2022

Preprint

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This paper presents an innovative approach to determine and model the kinetics of the catalytic oxidation of urea in alkaline medium on nickel(III) sites. Firstly, the kinetic law is established by considering two types of active sites, either from a chemically synthesized Ni-based powder or from a massive nickel electrode. Thus, the electrochemical regeneration kinetics of nickel(III) can be differentiated from the kinetics of the purely chemical pathway of NiOOH solid particles consumption by urea. Secondly, a mechanism for the urea indirect oxidation mediated by the nickel(III)/nickel(II) system is proposed to predict the formation of all the by-products, contained in the liquid phase that have been experimentally identified in our previous work. Finally, a model combining kinetic laws with diffusive and convective transport phenomena is constructed. The robustness and relevance of the latter are proven by comparing the experimental results obtained during laboratory-scale electrolyzes with those predicted by the model.

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Unlocking the potential of Pt-based and metal oxides catalysts in liquid fuel cells technologies: Performance and challenges

Che Ramli,

Pasupuleti,

Zainoodin

et al. 2024

Ain Shams Engineering Journal

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Towards outstanding performance of direct urea fuel cells through optimization of anode catalyst layer and operating conditions

Cited by 9 publications

References 34 publications

Indirect urea electrooxidation by nickel(III) in alkaline medium: From kinetic and mechanism to reactor modeling

Indirect urea electrooxidation by nickel(III) in alkaline medium: From kinetic and mechanism to reactor modeling

Urea indirect electrooxidation by nickel(III) in alkaline medium: from kinetics and mechanisms to reactor modeling

Unlocking the potential of Pt-based and metal oxides catalysts in liquid fuel cells technologies: Performance and challenges

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