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 [ Time:2020/5/12 ]
Scientists Develop New Approach to Efficiently Reduce Nitrogen to Ammonia
Author :ZHANG Shengbo

Scientists from the Institute of Solid State Physics under Hefei Institutes of Physical Science demonstrated for the first time of an oxygen-coordinated single-atom site with exceptional electrocatalytic nitrogen (N2) reduction reaction (NRR) activity toward ammonia (NH3) production.

Electrosynthesis of NH3 from the NRR at ambient conditions has been widely regarded as a green NH3 synthesis technology to replace traditional energy- and capital-intensive Haber-Bosch process.

The single-atom catalysts have emerged as a new form of catalysts with enormous potentials and superiorities over other forms of catalysts for numerous important reactions, including the NRR to produce ammonia. To date, however, the reported NRR single-atom electrocatalysts exclusively anchor the metal atoms to various supports via metal-nitrogen or metalcarbon coordination bonds and use them as the active sites.

The biomass-based precursors possess rich and uniformly distributed chemical functional groups (e.g., N- and O-containing functional groups) that can be readily used to regulate the metal ion impregnation and controllably anchor single-atoms to carbon supports via new coordination bonds to form new types of catalytic active coordination configurations.

In this work, a Fe single-atom electrocatalyst (Fe-SAs/LCC) was fabricated utilising lignocellulose surface oxygen functional groups to regulate Fe3+ impregnation and carbothermal reduction to create atomically dispersed Fe-(O-C2)4 sites on graphitic carbons.

Importantly, this work indicated that the NRR performances of Fe-SAs/LCC were very different using carbon cloth (CC) and glassy carbon (GC) electrodes.

This work confirmed the electrocatalytic NRR activity of oxygen-coordinated single-atom sites that enriched the functionality and application domain of single-atom catalysts. This work demonstrated the use of biomass derived lignocellulose for facile synthesis of single-atom catalysts opens a new avenue to large-scale synthesise carbon supported single-atom catalysts. These new findings would be of highly interest to the broad catalysis communities.

link to the paper: Electrocatalytically Active Fe-(O-C2)4 Single-Atom Site forEfficient Reduction of Nitrogen to Ammonia

(a) SEM images of LC. (b) TEM image and (c) the aberration-corrected HAADF-STEM image of Fe-SAs/LCC. (d) Optimised Fe-(O-C2)4 configuration. (e) End-on and side-on N2 adsorption on Fe-(O-C2)4 and corresponding Bader charge distribution of *N2 (yellow and blue represent charge accumulation and depletion, respectively. The charge density difference is computed as (N2- Fe-(O-C2)4)(Fe-(O-C2)4)(N2)). (f) Fe K edge XANES spectra of Fe-SAs/LCC, Fe foil and Fe2O3. (g) Fourier-transformed k3-weighted EXAFS spectra of Fe-SAs/LCC, Fe foil and Fe2O3 (Noting that the Fe foil is transformed by 0.7). (h) Dependence of RNH3 and FE on the applied potential for Fe-SAs/LCC/GC (the error bar represents three replicated experiments). (Image by ZHANG Shengbo)

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