Highly Enhanced OER Performance by Er-Doped Fe-MOF Nanoarray at Large Current Densities.

Yan Ma,Dunmin Lin,Guomei Mu,Yujie Miao,Fengyu Xie,Chenggang Xu,Wen Zeng

doi:10.3390/nano11071847

Yan Ma, Dunmin Lin + Show 5 more

Open Access

https://doi.org/10.3390/nano11071847

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Journal: Nanomaterials	Publication Date: Jul 16, 2021
Citations: 10	License type: CC BY 4.0

Affiliation: Sichuan Normal University, Chongqing University

Abstract

Great expectations have been held for the electrochemical splitting of water for producing hydrogen as a significant carbon-neutral technology aimed at solving the global energy crisis and greenhouse gas issues. However, the oxygen evolution reaction (OER) process must be energetically catalyzed over a long period at high output, leading to challenges for efficient and stable processing of electrodes for practical purposes. Here, we first prepared Fe-MOF nanosheet arrays on nickel foam via rare-earth erbium doping (Er0.4 Fe-MOF/NF) and applied them as OER electrocatalysts. The Er0.4 Fe-MOF/NF exhibited wonderful OER performance and could yield a 100 mA cm−2 current density at an overpotential of 248 mV with outstanding long-term electrochemical durability for at least 100 h. At large current densities of 500 and 1000 mA cm−2, overpotentials of only 297 mV and 326 mV were achieved, respectively, revealing its potential in industrial applications. The enhancement was attributed to the synergistic effects of the Fe and Er sites, with Er playing a supporting role in the engineering of the electronic states of the Fe sites to endow them with enhanced OER activity. Such a strategy of engineering the OER activity of Fe-MOF via rare-earth ion doping paves a new avenue to design other MOF catalysts for industrial OER applications.

Highlights

As a form of clean energy, hydrogen energy is of crucial importance in addressing the global energy crisis and greenhouse gas issues caused by increased consumption of fossil fuels sources
0.4 Fe-metal organic frameworks (MOFs) and Fe-MOF were characterized via X-ray diffraction
The structure of Er0.4 Fe-MOF and Fe-MOF were characterized via X-ray diffraction (XRD),as asshown shownininFigure

Summary

Introduction

As a form of clean energy, hydrogen energy is of crucial importance in addressing the global energy crisis and greenhouse gas issues caused by increased consumption of fossil fuels sources. Most reported MOF electrocatalysts have been evaluated in accordance with overpotentials and long-term stability under low current density, mostly less than 100 mA cm−2 , and these assessment criteria are not realistic for industrial applications [15]. To be used for industrial applications, OER catalysts must deliver large-current-density (500 mA cm−2 ) OER at low overpotentials. Nanomaterials 2021, 11, 1847 al applications, OER catalysts must deliver large-current-density (500 mA cm−2) OER at low overpotentials. OER electrocatalysts based on earth-abundant MOF alternatives at large current densities. There still are few reports about enhancing the intrinsic reports about enhancing the intrinsic OER activity of MOFs by rare-earth element dopactivity of MOFs by large rare-earth element doping, especially under large currents [23,24]. Schematic illustrating the fabrication process for Er0.4 Fe-MOF/NF

Methods

Preparation of RuO2 on NF

Electrochemical Measurements

Characterizations

Results

The spectra

Conclusions