Green synthesis of water splitting electrocatalysts: IrO<sub>2</sub> nanocages <i>via</i> Pearson's chemistry

Elmaalouf, Marine; Silva, Alexandre da; Durán, Silvia; Tard, Cédric; Comesaña‐Hermo, Miguel; Derouich, Sarra Gam; Briois, Valérie; Alloyeau, Damien; Giraud, Marion; Piquemal, Jean‐Yves; Péron, Jennifer

doi:10.1039/d2sc03640a

Cited by 3 publications

(2 citation statements)

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“…Electrochemical reduction of nitrate to ammonia goes through an eight-electron pathway, where a side reaction to generate other N-containing products or competitive hydrogen evolution can dominate, resulting in low Faradic efficiency and product selectivity. − Decades of effort have been invested to develop catalysts with high selectivity for the desired products. − Noble metal such as Pt has been considered a typical heterogeneous catalyst for nitrate reduction. − For nonprecious metals, Cu is considered a potential candidate for nitrate reduction to ammonia. − In a 1 M KOH solution, Cu can reach a Faradic efficiency of greater than 90% for nitrate reduction into ammonia . However, Cu tends to be deactivated due to cathodic corrosion in alkaline.…”

Section: Introductionmentioning

confidence: 99%

Synergy between Cu and Co in a Layered Double Hydroxide Enables Close to 100% Nitrate-to-Ammonia Selectivity

Wang,

Chen,

Tse

2023

J. Am. Chem. Soc.

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Nitrate electroreduction (NO 3 RR) holds promise as an energy-efficient strategy for the removal of toxic nitrate to restore the natural nitrogen cycle and mitigate the adverse impacts caused by overfertilization from suboptimal agricultural practices. However, existing catalysts suffer from limited electrocatalytic activity, poor selectivity, inadequate durability, and low scalability. To address this quadrilemma, in this study, we developed a cost-effective layered double hydroxide (LDH) electrocatalyst with a lamellar structure that presents trimetallic CuCoAl active sites on the nanomaterial surface. This codoping design enabled electrochemical upcycling of nitrate into ammonia exclusively and efficiently with an onset potential at 0 V vs RHE, where the electrocatalytic process is less energy intensive and has a lower carbon footprint than conventional practices. The synergistic interaction among Cu, Co, and Al further afforded a 99.5% Faradic efficiency (FE) and a yield rate of 0.22 mol h −1 g −1 for nitrate-to-ammonia electroreduction, surpassing the performance of state-of-the-art nonprecious metal NO 3 RR electrocatalysts over an extended operation period. To gain insights into the origin of the catalytic performance observed on LDH, control materials were employed to elucidate the roles of Cu and Co. Cu was found to improve the NO 3 RR onset potential despite displaying limited FE for ammonia synthesis, while Co was discovered to suppress the formation of nitrite byproduct though requiring large overpotential. Simulated wastewater containing phosphate and sulfate, which are typically present in industrial effluents, was used to further investigate the effect of electrolytes on NO 3 RR. Intriguingly, the use of phosphate buffer resulted in a superior yield rate and FE for ammonia production while simultaneously inhibiting nitrite byproduct formation compared with the sulfate case. These experimental findings were supported by density functional theory (DFT) calculations, which explored the adsorption strength of nitrate adducts adjacent to coadsorbed electrolytes on the LDH surface. Additionally, the relative free energies of NO 3 RR species were also computed to examine the proton-coupled electron transfer (PCET) mechanism on CuCoAl LDH, shedding light on the potential-dependent step (PDS) and the exclusive selectivity for nitrate-to-ammonia conversion. The CuCoAl LDH developed here offers scalability by eliminating the need for precious metals, rendering this earth-abundant catalyst particularly appealing for sustainable nitrate electrovalorization technology.

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Section: Introductionmentioning

confidence: 99%

Synergy between Cu and Co in a Layered Double Hydroxide Enables Close to 100% Nitrate-to-Ammonia Selectivity

Wang,

Chen,

Tse

2023

J. Am. Chem. Soc.

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“…[25][26][27][28][29] Lot of efforts have been invested to develop catalysts with high selectivity for desired products. [29][30][31][32][33][34] Noble metal such as Pt has been considered as a typical heterogeneous catalyst for nitrate reduction. [35][36][37] For non-precious metals, Cu is considered as a potential candidate for nitrate reduction to ammonia.…”

Section: Introductionmentioning

confidence: 99%

Selective Electroreduction of Nitrate into Ammonia on CuCoAl Layered Double Hydroxide for Sustainable Resourcification

Wang

Chen

Tse

2023

Preprint

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One-step nitrate electroreduction (NO3RR) is a promising strategy to generate ammonia in a straightforward and environmentally friendly manner. However, most catalysts suffer from limited electrocatalytic activity as well as poor selectivity. In this work, a tunable trimetallic CuCoAl layered double hydroxide (LDH) catalyst was designed to generate ammonia exclusively and efficiently with an onset potential at 0.13 V vs. RHE. The synergy among Cu, Co, and Al bestowed a 99.5 % Faradaic efficiency (FE) for ammonia with a yield rate of 0.22 mol h-1 g-1, rivaling the performance of state-of-the-art non-precious metal NO3RR electrocatalysts. Control materials were employed to elucidate the roles of Cu, Co, and Al toward lowering the overpotential and suppressing the formation of nitrite byproduct. DFT calculations were performed to further investigate the adsorption strength of anionic adducts and electrolytes on LDH surface to unravel the effects of buffer conditions on NO3RR performance. The scalable nature of our earth-abundant catalysts is particularly attractive due to the intrinsic low costs of the raw materials. We envision that this precious-metal-free catalyst can be generally applicable to other resourcification processes to achieve a future sustainable society.

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Synthesis of Silver(I) Complexes through In Situ Reactions of dppeda with dmp in the Presence of Silver Halides for Photocatalysis

Gao,

Li,

Mou

et al. 2024

Inorg. Chem.

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Due to the unique photosensitivity of silver compounds, they exhibit good photocatalytic activity as photocatalysts in the degradation of water pollutants. However, silver compounds have poor cycling stability and are prone to decomposition and reaction under light to form metallic silver, which greatly limits their practical application. Herein, a (2-(2-(diphenylphosphaneyl)ethyl)-9-methyl-1.10-phenanthroline (PSNNP)) pincer ligand was designed for stabilizing the central metal. The in situ-formed PSNNP ligand could be readily generated in one pot with the participation of silver halides. The reaction of silver halides with dppeda (N,N,N′,N′-tetra-(diphenylphosphanylmethyl)ethylene diamine) in the presence of dmp (2,9-dimethyl-1,10-phenanthroline) in acetonitrile afforded complexes Ag 2 X 2 (PSNNP) 2 (complexes 1, 2) (X = Cl, Br). Singlecrystal X-ray diffraction shows that the tridentate coordination of the pincer ligand provides strong binding with metal centers and leads to high stability of the pincer metal unit. The removal rate of rhodamine B (RhB) by complexes 1 and 2 can reach up to 100%, demonstrating an excellent photocatalytic degradation performance for organic dyes. The important effect of PSNNP ligands on photocatalytic properties after coordination with central metals was studied through experiments and discrete Fourier transform (DFT) calculations. The photocatalytic reaction mechanism of complexes 1 and 2 was also studied. This result provides an effective pathway for the first synthesis of PSNNP and interesting insights into photocatalytic degradation chemistry.

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Green synthesis of water splitting electrocatalysts: IrO₂ nanocages via Pearson's chemistry

Abstract: Highly porous iridium oxide structures are particularly well-suited for the preparation of porous catalyst layers needed in proton exchange membrane water electrolyzers. Herein, we report the formation of iridium oxide...

Cited by 3 publications

References 59 publications

Synergy between Cu and Co in a Layered Double Hydroxide Enables Close to 100% Nitrate-to-Ammonia Selectivity

Synergy between Cu and Co in a Layered Double Hydroxide Enables Close to 100% Nitrate-to-Ammonia Selectivity

Selective Electroreduction of Nitrate into Ammonia on CuCoAl Layered Double Hydroxide for Sustainable Resourcification

Synthesis of Silver(I) Complexes through In Situ Reactions of dppeda with dmp in the Presence of Silver Halides for Photocatalysis

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Green synthesis of water splitting electrocatalysts: IrO2 nanocages via Pearson's chemistry

Abstract: Highly porous iridium oxide structures are particularly well-suited for the preparation of porous catalyst layers needed in proton exchange membrane water electrolyzers. Herein, we report the formation of iridium oxide...

Cited by 3 publications

References 59 publications

Synergy between Cu and Co in a Layered Double Hydroxide Enables Close to 100% Nitrate-to-Ammonia Selectivity

Synergy between Cu and Co in a Layered Double Hydroxide Enables Close to 100% Nitrate-to-Ammonia Selectivity

Selective Electroreduction of Nitrate into Ammonia on CuCoAl Layered Double Hydroxide for Sustainable Resourcification

Synthesis of Silver(I) Complexes through In Situ Reactions of dppeda with dmp in the Presence of Silver Halides for Photocatalysis

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Product

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Green synthesis of water splitting electrocatalysts: IrO₂ nanocages via Pearson's chemistry