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Journal of Photocatalysis

Editor-in-Chief

ISSN (Print): 2665-976X
ISSN (Online): 2665-9778

Research Article

Enhancing Electrocatalytic N2 Conversion to NH3 by MnO2 Ultralong Nanowires with Oxygen Vacancies

Author(s): Guangbin Wang, Renna Zhao, Fahao Ma, Zeyan Wang, Peng Wang, Yuanyuan Liu, Hefeng Cheng, Ying Dai, Zhaoke Zheng* and Baibiao Huang*

Volume 2, Issue 2, 2021

Published on: 07 April, 2021

Article ID: e070421192730 Pages: 7

DOI: 10.2174/2665976X02666210407142545

Abstract

Background: At present, industrial synthesis of NH3 mainly relies on the Haber-Bosch process, which is characterized by harsh reaction conditions and high energy consumption. Electrochemical nitrogen reduction is considered to be a mild and sustainable alternative method for producing NH3, but efficient electrocatalyst under ambient conditions is the prerequisite for NH3 production.

Objective: To demonstrate that CP@MnO2 ultralong nanowires are a highly-efficient electrocatalyst for N2 reduction reaction (NRR) under ambient conditions.

Methods: The α-phase MnO2 synthesized by one-step hydrothermal method has an ultralong nanowires structure and oxygen vacancy defects. The catalysts were characterized by XRD, TEM, XPS, etc. The produced NH3 was estimated by indophenol blue method by UV-vis absorption spectra.

Results: Such catalyst attains high Faradaic efficiency (FE) of 8.8% and a large NH3 yield of 1.13×10−10 mol cm−2 s−1 at −0.7 V versus reversible hydrogen electrode in 0.1 M Na2SO4. In addition, the catalyst also shows high electrochemical stability and selectivity for NH3 formation.

Conclusion: MnO2 ultralong nanowires can expose higher density of active sites and the spontaneously formed oxygen vacancies can manipulate the electronic structure of manganese oxides and provide coordination unsaturation sites (CUS) to enhance the adsorption of N2, which is the main reason for the high activity of the catalyst.

Keywords: MnO2 ultralong nanowires, N2 reduction reaction, electrocatalysis, oxygen vacancies, ambient conditions, active sites.

Graphical Abstract

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