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ZnO Quantum Dots Coupled with Graphene toward Electrocatalytic N 2 Reduction: Experimental and DFT Investigations
Author(s) -
Liu Yaping,
Li Yubiao,
Huang Dajian,
Zhang Hu,
Chu Ke
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201902156
Subject(s) - graphene , faraday efficiency , catalysis , materials science , electrochemistry , redox , quantum dot , oxide , adsorption , quantum yield , chemical engineering , yield (engineering) , nanotechnology , inorganic chemistry , chemistry , electrode , organic chemistry , composite material , metallurgy , physics , quantum mechanics , engineering , fluorescence
Electrochemical reduction of N 2 to NH 3 is a promising method for artificial N 2 fixation, but it requires efficient and robust electrocatalysts to boost the N 2 reduction reaction (NRR). Herein, a combination of experimental measurements and theoretical calculations revealed that a hybrid material in which ZnO quantum dots (QDs) are supported on reduced graphene oxide (ZnO/RGO) is a highly active and stable catalyst for NRR under ambient conditions. Experimentally, ZnO/RGO was confirmed to favor N 2 adsorption due to the largely exposed active sites of ultrafine ZnO QDs. DFT calculations disclosed that the electronic coupling of ZnO with RGO resulted in a considerably reduced activation‐energy barrier for stabilization of *N 2 H, which is the rate‐limiting step of the NRR. Consequently, ZnO/RGO delivered an NH 3 yield of 17.7 μg h −1 mg −1 and a Faradaic efficiency of 6.4 % in 0.1 m Na 2 SO 4 at −0.65 V (vs. RHE), which compare favorably to those of most of the reported NRR catalysts and thus demonstrate the feasibility of ZnO/RGO for electrocatalytic N 2 fixation.