Enhanced electrocatalytic oxygen evolution of α-Co(OH)₂nanosheets on carbon nanotube/polyimide films

Abstract

The future of energy supply depends on innovative breakthroughs in the development of highly efficient, sustainable and low-cost systems for renewable energy conversion and storage. Water splitting is a promising and appealing solution. In this work, we report Co(OH)2 on the carbon nanotube/polyimide film (PI/CNT-Co(OH)2) as an efficient electrocatalyst for the oxygen evolution reaction (OER). The PI/CNT film allows intimate growth of Co(OH)2 nanosheets on its surface. The nanosheet structure of Co(OH)2 and the underlying PI/CNT film facilitate the good OER performance of the PI/CNT-Co(OH)2 film. Co(OH)2 nanosheets on the PI/CNT film afford an earlier onset of oxygen evolution, a low overpotential of 317 mV and a small Tafel slope of 49 mV per decade in alkaline media. This work applies the PI/CNT film in water splitting to enhance the OER electrocatalytic activity of Co(OH)2, which opens up a promising avenue for the exploration of highly active electrocatalysts that can replace noble-metal based catalysts for the OER.

Electrochemical Water Oxidation Catalyzed by an In Situ Generated α‐Co(OH)2 Film on Zeolite‐Y Surface

“…[31] Herein, we report an in situ generated zeolite-Y-supported a-Co(OH) 2 film as aC o-OECw ith enormous stability and good efficiency.W er eport av ery simple but unique technique to generate at hin-film of a-Co(OH) 2 of a-Co(OH) 2 on the surface of zeolite-Y also remains the same. Moreover,t he efficiency of this heterogeneous electrocatalytic system is highert han for the existing, previously reported, aCo(OH) 2 -based electrocatalysts operating at alkalinep H. [29,30,32] Results and Discussion Figure 1c ompares 6 (Figure 1) matches well with that of previously reported Co II -exchanged zeolite-Y. [33] As shown in Figure 1, the relative intensities of the diffraction peaks at 10.1 and 11.88 are found to be reversed in Y-Co II (H 2 O) 6 .T his could be attributed to ac hange in the structure factor of zeolite-Y upon exchange with ar elatively heavier ion (Co II ), as has been reportedf or Cs I -exchanged zeolite-Y.…”

“…[28] Recently, a-Co(OH) 2 film deposited on carbon nanotubes and Ag-nanowires has been shown to act as efficient electrocatalyst for oxygen evolution from water at alkaline pH. [29,30] Zeolite-Y supported b-Co(OH) 2 has also been shownt ob ean efficient catalystf or photochemical water oxidation. [31] Herein, we report an in situ generated zeolite-Y-supported a-Co(OH) 2 film as aC o-OECw ith enormous stability and good efficiency.W er eport av ery simple but unique technique to generate at hin-film of a-Co(OH) 2 of a-Co(OH) 2 on the surface of zeolite-Y also remains the same.…”

“…As imilar type of morphology was observed for aCo(OH) 2 deposited on carbon nanotubes and Ag-nanowires. [29,30] To gain more insight into the morphology of the a-Co(OH) 2 film, TEM analysisw as performed on all samples. Figure3a-d depicts the TEM images of a-Co(OH) 2 coveringz eolite-Y.T hese images clearly showablack zeolite core, and at hin curved film/sheet can be observed at the periphery of the zeolite crystal surface owing to the formation of a-Co(OH) 2 upon dipping at hin layer of Y-Co II (H 2 O) 6 ,p repared with 0.5 wt %N afion, in 0.1 m KOH.…”

Liquid Exfoliated Co(OH)2 Nanosheets as Low‐Cost, Yet High‐Performance, Catalysts for the Oxygen Evolution Reaction

“…[28,29] Empirically, it has been shown that, like many other layered materials, Co(OH)2 performance improves when exfoliated into thin 2D nanosheets. [28,30,31] However, in the past, LDH nanosheets have been produced by relatively complex methods such as hydrothermal synthesis coupled with exfoliation by ion exchange. [6,7,24,32] Here we take a simpler approach, using LPE as a top-down method to produce Co(OH)2 nanosheets directly from the parent layered crystal.…”

“…This performance is not exceptional: Co(OH)2 electrocatalysts reach 10 mA cm -2 at overpotentials in the range 300 -450 mV. [28,30,45] However, LPE-based samples have a significant advantage in that production and processing is very simple. This will facilitate electrode optimisation leading to significant improvements in the OER performance.…”