Overall Water‐Splitting Electrocatalysts Based on 2D CoNi‐Metal‐Organic Frameworks and Its Derivative. Issue 21 (16th August 2018)

• Record Type: Journal Article
• Authors: Liu, Mengjie; Zheng, Weiran; Ran, Sijia; Boles, Steven T.; Lee, Lawrence Yoon Suk
• Is Part Of: Advanced materials interfaces. Volume 5:Issue 21(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-08-16
• Subjects: 2D metal–organic frameworks -- bimetallic metal–organic frameworks -- electrocatalyst -- nanoplate array -- water splitting; Materials science -- Periodicals; 620.11
• DOI: 10.1002/admi.201800849
• Languages: English
• ISSNs: 2196-7350

Abstract

Abstract: Efficient electrocatalysts composed of non‐precious elements are central to the development of overall water‐splitting system. Herein, it is demonstrated that 2D CoNi‐metal‐organic framework (CoNi‐MOF) array grown directly on a Cu substrate is a highly efficient and stable electrocatalyst for oxygen evolution reaction with a low overpotential (265 mV at 10 mA cm −2 ) in alkaline medium. With the combination of in situ conducting atomic force microscopy and two‐point conductivity measurements, it is revealed that the electron transfer is facilitated along the Z ‐axis better than the other directions, which can lead to an enhanced catalytic activity. In addition, a simple annealing treatment converts this 2D CoNi‐MOF to a hybrid nanoplate array of metallic nitrides on an amorphous carbon network, which catalyzes the hydrogen evolution reaction with a compatible overpotential of 120 mV (at 10 mA cm −2 ) and excellent stability. The overall water splitting using these 2D CoNi‐MOF‐based catalysts shows a 99% Faradaic efficiency at 1.64 V, suggesting a promising pathway forward for the commercial realization of complete water‐splitting systems. Abstract : 2D bimetallic CoNi‐metal‐organic framework (CoNi(1:1)‐MOF) with the (2 2 ¯ 0) crystalline facets exposed catalyzes oxygen evolution at a low overpotential of 265 mV. CoNiN@C prepared using CoNi‐MOF as a precursor shows comparable hydrogen evolution rate in alkaline solution. Using CoNi(1:1)‐MOF and CoNiN@C, overall water splitting is achieved with 99.0% (hydrogen evolution reaction) and 98.9% (oxygen evolution reaction) Faradaic efficiencies.