In‐situ One‐Step Preparation of Nickel‐Tipped N‐doped Carbon Nanotubes for Oxygen Reduction

Huai, Jie; Ma, Kongshuo; Lu, Yizhong; Chen, Tao; Zhao, Zhenlu

doi:10.1002/cctc.201901239

Cited by 9 publications

(6 citation statements)

References 43 publications

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“…Occasionally, we have found in experiments that Ni electrodes (Ni foam or Ni mesh, widely exploited as the supporting substrate for nanostructured electrocatalysts toward nitrate, ,, carbon dioxide, , or oxygen reduction − ) can be self-activated after consecutive cycles during NO 3 RR, exhibiting outstanding performance in nitrate-to-ammonia conversion with appreciably high selectivity, longevity, and Faradaic efficiency. Its role in facilitating NO 3 RR has been generally overlooked.…”

Section: Introductionmentioning

confidence: 99%

Self-Activated Ni Cathode for Electrocatalytic Nitrate Reduction to Ammonia: From Fundamentals to Scale-Up for Treatment of Industrial Wastewater

Zheng

Zhu

Zhang

et al. 2021

Environ. Sci. Technol.

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Electrocatalytic reduction has recently received increasing attention as a method of converting waste nitrate into value-added ammonia, but most studies have focused on complex strategies of catalyst preparation and little has been done in the way of large-scale demonstrations. Herein, we report that in situ activation of a pristine Ni electrode, either on a lab scale or a pilot scale, is effective in facilitating nitrate reduction to ammonia, exhibiting extraordinarily high activity, selectivity, and stability. The self-activated Ni cathode has a robust capacity to reduce nitrate over a wide range of concentrations and achieves great conversion yield, NH4 +–N selectivity, and Faradaic efficiency, respectively, 95.3, 95.5, and 64.4% at 200 mg L–1 NO3 ––N and 97.8, 97.1, and 90.4% at 2000 mg L–1 NO3 ––N, for example. Fundamental research indicates that Ni(OH)2 nanoparticles are formed on the Ni electrode surface upon self-activation, which play crucial roles in governing nitrate reduction reaction (NO3RR) through the atomic H*-mediated pathway and accordingly suppressing hydrogen evolution reaction. More importantly, the self-activated Ni(OH)2@Ni cathode can be easily scaled up to allow large volumes of real industrial wastewater to be processed, successfully transferring nitrate into ammonia with high yields and Faradaic efficiency. This study demonstrates a new, mild, and promising method of cleaning nitrate-laden wastewater that produces ammonia as a valuable byproduct.

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Section: Introductionmentioning

confidence: 99%

Self-Activated Ni Cathode for Electrocatalytic Nitrate Reduction to Ammonia: From Fundamentals to Scale-Up for Treatment of Industrial Wastewater

Zheng

Zhu

Zhang

et al. 2021

Environ. Sci. Technol.

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“…Very recent studies on metal and N‐codoped graphene/carbon nanostructures showed great promise that these materials can replace Pt in fuel cell ORR catalysis [10,14] . Various experimental and theoretical studies have been performed on PGM‐free nanostructure with Mn, Fe, Co, Ni, and Cu metal centers, and the observed activities have been found to be comparable to that obtained with the standard Pt catalyst [10,14–25] . However, the durability of PGM‐free systems is still significantly lower than that of Pt catalysts [26,27] .…”

Section: Introductionmentioning

confidence: 99%

“…[ 10 , 14 ] Various experimental and theoretical studies have been performed on PGM‐free nanostructure with Mn, Fe, Co, Ni, and Cu metal centers, and the observed activities have been found to be comparable to that obtained with the standard Pt catalyst. [ 10 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ] However, the durability of PGM‐free systems is still significantly lower than that of Pt catalysts. [ 26 , 27 ] Most studies of PGM‐free ORR catalysts have focused on Fe‐ and Co‐based nitrogen‐doped carbons obtained by pyrolysis from molecular precursors.…”

Section: Introductionmentioning

confidence: 99%

Origin of the Rarely Reported High Performance of Mn‐doped Carbon‐based Oxygen Reduction Catalysts

Samala

Grinberg

2022

ChemSusChem

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Recent efforts to develop durable high‐performance platinum‐group metal (PGM)‐free oxygen reduction reaction (ORR) electrocatalysts have focused on Fe‐ and Co‐based molecular and pyrolyzed catalysts. While Mn‐based catalysts have advantages of lower toxicity and higher durability, their activity has been generally poor. Nevertheless, several examples of high‐performance Mn‐based catalysts have been reported. Thus, it is necessary to understand why Mn‐based materials much more rarely show high catalytic ORR performance and to determine the factors that can lead to the achievement of such high performance in these rare cases. We have studied the effects of the changes in the macrocycle structure, axial ligand, distance between the active sites, interactions with the dopant N atoms and the presence of an extended carbon network on the ORR catalysis of various Mn‐, Fe‐, and Co‐based systems through the comparison of the adsorption energies of the ORR intermediates. We find that the sensitivity to the local environment changes is the largest for Mn and is the smallest for Co, with Fe between Mn and Co. Our results showed that the strong binding of OH by Mn and the strong sensitivity of the Mn to the modification of its environment necessitate a precise combination of local environment changes to achieve a high onset potential (Vonset) in Mn‐based catalysts. By contrast, the weaker binding of OH by Fe and Co and their weaker sensitivity to local environment changes lead to a wide variety of local environments with favorable catalytic activity (Vonset>0.7 V) for Co‐ and Fe‐based systems. This explains the scarcity of reported Mn‐based pyrolyzed catalysts and suggests that precise material synthesis and engineering of the active site can achieve high‐performance Mn‐based ORR electrocatalysts with high activity and durability.

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“…S4a‐d). [ 42 ] Additionally, E‐NiCo 2 S 4 /SBS‐NCNTs have rigid characteristics, a distinct bamboo shape, and more uniform diameter of carbon nanotube. Due to the possible synergistic effect between melamine and surface‐nanosized nickel foamed, uniform encapsulated NiCo 2 S 4 ‐based nitrogen‐doped carbon nanotubes with straight bamboo shape can still be obtained in the absence of exogenous reducing gas, such as H 2 .…”

Section: Resultsmentioning

confidence: 99%

Encapsulated NiCo₂S₄‐based straight bamboo‐shaped N‐CNT as efficient and stable oxygen electrocatalysts

Gao

Zhao

2021

Electrochemical Science Adv

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Developing highly effective and stable non-precious bifunctional oxygen electrocatalysts is crucial and challenging. Herein, we report nano-mediated straight bamboo-shaped nitrogen-doped carbon nanotubes modified with encapsulated NiCo 2 S 4 -based nanoparticles (E-NiCo 2 S 4 /SBS-NCNTs) by electrodeposition and procedural calcination strategy, in which nitrogen-doped carbon nanotubes with straight bamboo shape (SBS-NCNTs) show more average diameter and encapsulated NiCo 2 S 4 -based nanoparticles (E-NiCo 2 S 4 ) are coated by carbon, and what makes us even more excited is that they are evenly dispersed on SBS-NCNTs surface, not just at the tip or inside. When applied for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), E-NiCo 2 S 4 /SBS-NCNTs show excellent catalytic activity, and onset potential (E onset ) in OER and ORR is only 1.52 V and 0.95 V (vs. RHE) in 0.1 M KOH, respectively. More importantly, the hybrids exhibit good methanol tolerance, with almost unchanged for ORR performance after adding 0.5 M methanol, and it has highly stability, the current density dropped by 22% after 7 h of reaction. The interaction of NiCo 2 S 4 with the external carbon layer can greatly enhance the electrocatalytic activity toward the OER and it has a complete 4ereaction process toward the ORR. The excellent electrocatalytic activity is mainly due to synergistic enhancement effect, in which SBS-NCNTs with highly catalytic activity provide good conductivity, expose more active sites and promotes fast mass transfer; Carbon-coated NiCo 2 S 4 -based nanoparticles can improve the local work function of SBS-NCNT through synergistic electronic interaction, promoting O 2 adsorption, ensure rapid electron transport, and enable SBS-NCNT to improve its electrocatalytic activity. Because of the weakness of Ostwald effect and synergistic enhancement, the stability and catalytic activity of NiCo 2 S 4 -based nanoparticles can be greatly improved. All these advantages can synergistically improve the electrocatalytic efficiency and make it become one of the most promising bifunctional oxygen electrocatalysts.

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In‐situ One‐Step Preparation of Nickel‐Tipped N‐doped Carbon Nanotubes for Oxygen Reduction

Cited by 9 publications

References 43 publications

Self-Activated Ni Cathode for Electrocatalytic Nitrate Reduction to Ammonia: From Fundamentals to Scale-Up for Treatment of Industrial Wastewater

Self-Activated Ni Cathode for Electrocatalytic Nitrate Reduction to Ammonia: From Fundamentals to Scale-Up for Treatment of Industrial Wastewater

Origin of the Rarely Reported High Performance of Mn‐doped Carbon‐based Oxygen Reduction Catalysts

Encapsulated NiCo₂S₄‐based straight bamboo‐shaped N‐CNT as efficient and stable oxygen electrocatalysts

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In‐situ One‐Step Preparation of Nickel‐Tipped N‐doped Carbon Nanotubes for Oxygen Reduction

Cited by 9 publications

References 43 publications

Self-Activated Ni Cathode for Electrocatalytic Nitrate Reduction to Ammonia: From Fundamentals to Scale-Up for Treatment of Industrial Wastewater

Self-Activated Ni Cathode for Electrocatalytic Nitrate Reduction to Ammonia: From Fundamentals to Scale-Up for Treatment of Industrial Wastewater

Origin of the Rarely Reported High Performance of Mn‐doped Carbon‐based Oxygen Reduction Catalysts

Encapsulated NiCo2S4‐based straight bamboo‐shaped N‐CNT as efficient and stable oxygen electrocatalysts

Contact Info

Product

Resources

About

Encapsulated NiCo₂S₄‐based straight bamboo‐shaped N‐CNT as efficient and stable oxygen electrocatalysts