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 [ Time:2020/3/4 ]
A New Method for constructing high formation energy anion vacancy
Author :JIN Meng

Scientists from the Institute of Solid State Physics, Hefei Institutes of Physical Science have synthesized a novel partially reduced Cu3P catalyst rich in phosphorus vacancy defects by using doped-oxygen induced strategy and have made progress in investigating the performance and mechanism of electrocatalytic nitrogen fixation.

This work provides a promising strategy to design and construct efficient nitrogen reduction reaction (NRR) catalysts with anion vacancy defects for good theoretical and experimental guidance.

Engineering vacancy defects attract attention because it can adjust the chemical and physical properties of various materials and the defect sites would serve as the active center for enhancing the catalytic performance.

Especially the anion vacancy defects can be used as electrophilic centers to facilitate the combination with electron-rich nitrogen and activate nitrogen molecules to enhance the nitrogen reduction process.

However, most studies have concentrated on oxygen vacancy defects considering the low formation energy. Sulfur, nitrogen, and phosphorus anion vacancy defects with higher formation energy are rarely reported which deserves an in-depth investigation.

In this new work, the researchers found that phosphorus vacancy defects generated by utilizing the doped-oxygen induced strategy can be employed as high catalytic active species for electrochemical NRR process.

An ammonia yield of 28.12 g h-1 cm-2 with a high Faradaic efficiency of 17.5% was achieved at ambient conditions for partially reduced Cu3P electrode with abundant phosphorus vacancies (RO-Cu3P), about 3.4 times higher than that for prepared pure Cu3P electrode.

By using DFT method, the NRR reaction mechanism and the effect of doping concentration on performance were also studied.

This work was supported by the young project of Anhui Provincial Natural Science Foundation (Grant no.1908085QB83) and China Postdoctoral Science Foundation funded project (No. 2019M652224). The work was carried out at LvLiang Cloud Computing Center of China, and the calculations were performed on TianHe-2.

(a) Production yield of the NH3 and N2H4 on different electrode
(b) The proposed reaction pathway for formation of NH3 and N2H4 from molecular dinitrogen by using RO-Cu3P electrode as catalysts
(c) Free-energy diagrams of NRR on the surface vacancy of RO-Cu3P catalyst with different concentrations of doped oxygen (Image by JIN Meng)


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