Surface Reconstruction of Cobalt-Based Polyoxometalate and CNT Fiber Composite for Efficient Oxygen Evolution Reaction

Abstract

Polyoxometalates (POMs), as carbon-free metal-oxo-clusters with unique structural properties, are emerging water-splitting electrocatalysts. Herein, we explore the development of cobalt-containing polyoxometalate immobilized over the carbon nanotube fiber (CNTF) (Co4POM@CNTF) towards efficient electrochemical oxygen evolution reaction (OER). CNTF serves as an excellent electron mediator and highly conductive support, while the self-activation of the part of Co4POM through restructuring in basic media generates cobalt oxides and/or hydroxides that serve as catalytic sites for OER. A modified electrode fabricated through the drop-casting method followed by thermal treatment showed higher OER activity and enhanced stability in alkaline media. Furthermore, advanced physical characterization and electrochemical results demonstrate efficient charge transfer kinetics and high OER performance in terms of low overpotential, small Tafel slope, and good stability over an extended reaction time. The significantly high activity and stability achieved can be ascribed to the efficient electron transfer and highly electrochemically active surface area (ECSA) of the self-activated electrocatalyst immobilized over the highly conductive CNTF. This research is expected to pave the way for developing POM-based electrocatalysts for oxygen electrocatalysis.

Nickel‐Foam‐ and Carbon‐Nanotubes‐Fiber‐Supported Bismuth Oxide/Nickel Oxide Composite; Highly Active and Stable Bifunctional Electrocatalysts for Water Splitting in Neutral and Alkaline Media

“…Using the well‐known Debye Scherer equation ( D avg = ), the average crystallite size ( D avg ) of Bi 2 O 3 /NiO and Bi 2 O 3 /NiO‐CNTF is calculated to be 34.4 and 37.8 nm, respectively. Figure 1b depicts the PXRD spectra of Bi 2 O 3 /NiO‐CNTF, which shows that due to amorphous phase of CNTF from 20° to 30°, [ 26 ] some prominent peaks of Bi 2 O 3 /NiO are suppressed. However, the major peaks with planes (120), (200), (302), (242), and (220) confirm its deposition onto CNTF.…”

“…[25] Herein, we have reported the synthesis of NiO/Bi 2 O 3 -based material through a facile solution mixing method and used it as electrocatalyst for water splitting by depositing it over nickel foam (NF) and quasi-1D carbon nanotube fiber (CNTF) through our previously reported drop-casting method. [26] NF and CNTF increased the electrical conductivity of the composite by increasing the charge-carrier density and Bi 2 O 3 /NiO served as the active sites by providing synergistic effect for the electrochemical water splitting. The oxidized NiOOH plays an important role for the excellent catalytic activity, whereas Bi 2 O 3 has large surface area and helps to gain stability during electrocatalysis.…”

Optimized mass transfer in a Pt-based cathode catalyst layer for PEM fuel cells

“…Covalent organic frameworks (COFs) are emerging porous materials with adjustable pores that allow faster gas delivery to the catalyst with excellent chemical stability. [86][87][88] A recent work shows that the porosity, chemical stability, and mass transfer performance of ionomers could be elevated by adding a COF material to the ionomer. 44 A mesoporous (2.8 to 4.1 nm) sulfonic acid-based COF was incorporated into the ionomer, which improved the TPB by reducing O 2 transport resistance in the CL, resulting in enhanced power density (Fig.…”

A Cluster-Type Self-Healing Catalyst for Stable Saline–Alkali Water Splitting

“…A comprehensive understanding of surface reconstruction processes plays a crucial role in establishing a clear structure-composition-property relationship to pursue highly efficient electrocatalysts. Therefore, structural reconstruction has emerged as a promising strategy for enhancing the catalytic activity of electrocatalysts [51,52]. Hence, highly active NC and high CV potential (1.5-1.7 V vs. RHE) create a fast and strong oxidative environment for the reconstruction of NiFe-MOF, providing thermodynamic conditions for Fe to undergo adaptive strong oxidation.…”