Boosting Reaction Kinetics of N2 Electrocatalysis via Adsorption Enhancement and Confinement of Adsorbates

Boosting Reaction Kinetics of N2 Electrocatalysis via Adsorption Enhancement and Confinement of Adsorbates

Bibliographic Details
Main Author: Tian, Yujing
Language:English
Published: University of Cincinnati / OhioLINK 2020
Subjects:
Chemical Engineering
nitrogen reduction reaction
TiO2 nanotube array
confinement effect
restricted intermediates
NiFeB nanoflowers
boost reaction kinetics
Online Access:http://rave.ohiolink.edu/etdc/view?acc_num=ucin159239534417192
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spelling ndltd-OhioLink-oai-etd.ohiolink.edu-ucin1592395344171922021-08-03T07:15:21Z Boosting Reaction Kinetics of N2 Electrocatalysis via Adsorption Enhancement and Confinement of Adsorbates Tian, Yujing Chemical Engineering nitrogen reduction reaction TiO2 nanotube array confinement effect restricted intermediates NiFeB nanoflowers boost reaction kinetics The synthesis of ammonia (NH3) from artificial N2 fixation is extremely challenging due to the sluggish reaction kinetics associated with six proton-couple electron transfer steps.4 Currently, the industrial production of NH3 heavily relies on the Haber-Bosch process, which operates at high temperatures (300-550 degree C) and pressure (200-350 atm).1 Therefore, it is highly desired to develop an alternative process to synthesize NH3 with renewable energy sources under ambient conditions. Electrochemical synthesis of NH3 from N2 reduction reaction (NRR) using water as the proton source can potentially become a supplementary route to the Haber-Bosch process. The grand challenge of electrocatalytic NRR is to develop active and selective catalysts that yield NH3 at a rate of industrial relevance.2 The search of such catalysts is hindered by the slow reaction kinetics of electrocatalytic NRR under ambient conditions resulting from the high dissociation energy of N?N triple bond, low N2 solubility in water, and weak N2 adsorption on the catalyst surfaces.2 To overcome these limitations, here we demonstrate two strategies to boost reaction kinetics of N2 electrocatalysis.The first strategy is applying confinement of intermediates in blue TiO2 nanotube arrays to boost the reaction rate of nitrogen reduction. The space confinement effect of reactive intermediates in highly ordered blue TiO2 nanotubes (b-TiO2) encapsulating metal oxide can significantly enhance the electrocatalytic NRR activity and selectivity. The restricted local intermediates inside b-TiO2 nanotube can increase the surface coverage of reactive sites, thus promote the reaction rate of NH3 synthesis. Benefiting from confinement effect of intermediates, the b-TiO2 nanotubes encapsulating metal oxide catalysts show both higher production rate and Faradaic efficiency (FE) of NH3 than the combined ones of individual metal oxide and b-TiO2 electrodes.The second strategy focuses on improving N2 adsorption strength by incorporating boron into Ni/Fe metals in amorphous NiFeB nanoflowers. Recent research indicates that hypovalent boron species can mimic TMs (transition metals) with the electron's “acceptance - donation” process. Some studies reported that boron doping could enhance the NRR performance of graphene, in which boron can break the intrinsic equilibrium of graphene molecular orbitals and the positively charged boron is conducive to the adsorption of N2 to improve the NRR activity. A series of amorphous NiFeB nanoflowers were fabricated with varying atomic ratios of Ni/Fe by a facile chemical- reduction method. The increased catalytic activity of NiFeB nanoflowers can be ascribed to B enhanced N2 adsorption and abundant surface defects. 2020-11-04 English text University of Cincinnati / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=ucin159239534417192 http://rave.ohiolink.edu/etdc/view?acc_num=ucin159239534417192 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws.
collection NDLTD
language English
sources NDLTD
topic Chemical Engineering
nitrogen reduction reaction
TiO2 nanotube array
confinement effect
restricted intermediates
NiFeB nanoflowers
boost reaction kinetics
spellingShingle Chemical Engineering
nitrogen reduction reaction
TiO2 nanotube array
confinement effect
restricted intermediates
NiFeB nanoflowers
boost reaction kinetics
Tian, Yujing
Boosting Reaction Kinetics of N2 Electrocatalysis via Adsorption Enhancement and Confinement of Adsorbates
author Tian, Yujing
author_facet Tian, Yujing
author_sort Tian, Yujing
title Boosting Reaction Kinetics of N2 Electrocatalysis via Adsorption Enhancement and Confinement of Adsorbates
title_short Boosting Reaction Kinetics of N2 Electrocatalysis via Adsorption Enhancement and Confinement of Adsorbates
title_full Boosting Reaction Kinetics of N2 Electrocatalysis via Adsorption Enhancement and Confinement of Adsorbates
title_fullStr Boosting Reaction Kinetics of N2 Electrocatalysis via Adsorption Enhancement and Confinement of Adsorbates
title_full_unstemmed Boosting Reaction Kinetics of N2 Electrocatalysis via Adsorption Enhancement and Confinement of Adsorbates
title_sort boosting reaction kinetics of n2 electrocatalysis via adsorption enhancement and confinement of adsorbates
publisher University of Cincinnati / OhioLINK
publishDate 2020
url http://rave.ohiolink.edu/etdc/view?acc_num=ucin159239534417192
work_keys_str_mv AT tianyujing boostingreactionkineticsofn2electrocatalysisviaadsorptionenhancementandconfinementofadsorbates
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