Platinum Nanoparticles Decorated IrO₂@MWCNT as an Improved Catalyst for Oxygen Evolution Reaction

Abstract

In this paper, IrO2 nanoparticles supported on multi‐walled carbon nanotubes (MWCNTs) are synthesized via a facile hydrothermal method and calcination process at different temperature. Platinum nanoparticles decorated IrO2@MWCNT‐400 °C are prepared by chemical reduction method. The influence of MWCNTs and Pt on physicochemical properties and oxygen evolution reaction (OER) activity of IrO2@MWCNT composites were studied via transmission electron microscope (TEM), X‐ray diffraction (XRD), Raman spectra, thermogravimetric analysis (TGA), X‐ray photoelectron spectroscopic (XPS) and electrochemical methods. Among the samples, Pt/IrO2@MWCNT‐400 °C exhibits better catalytic activity with an overpotential of 270 mV at the current density of 10 mA cm−2 with a low Tafel slope of 85.1 mV dec−1. The outstanding OER performance of Pt/IrO2@MWCNT‐400 °C is ascribed to the introduction of the MWCNTs, which can not only act as a support to prevent agglomeration of IrO2 nanoparticles that produces high surface area of catalytic sites, but also facilitates electron transfer between IrO2 nanoparticles and MWCNTs. On the other hand, the Pt optimizes electronic structure for excellent electrocatalytic performance. Therefore, the Pt/IrO2@MWCNT‐400 °C catalyst is a good choice for application in OER.

Simultaneously Improved Activity and Stability for Acidic Water Oxidation of IrRu Oxides by a Dual Role of Tungsten Doping

“…The peak at ∼800 cm −1 is assigned to W−O in WO 3−x , 38,39 which almost disappears with increasing applied potential, suggesting the leaching of WO 3−x during OER (Figure S25). The peaks at ∼525 cm −1 correspond to the E g mode of Ir−O−Ir (Ir 4+ )/Ru−O−Ru (Ru 4+ ) vibration in rutile IrO 2 /RuO 2 , 40 while the peaks at ∼600 and 706 cm −1 represent the A 1g modes of Ir−O and Ru− O stretch, respectively. 40,41 According to the previous report, 42 the Ir 4+ species can be further oxidized into higher oxidation states of Ir >4+ in the range of 1.2−1.7 V (vs RHE).…”

“…The peaks at ∼525 cm −1 correspond to the E g mode of Ir−O−Ir (Ir 4+ )/Ru−O−Ru (Ru 4+ ) vibration in rutile IrO 2 /RuO 2 , 40 while the peaks at ∼600 and 706 cm −1 represent the A 1g modes of Ir−O and Ru− O stretch, respectively. 40,41 According to the previous report, 42 the Ir 4+ species can be further oxidized into higher oxidation states of Ir >4+ in the range of 1.2−1.7 V (vs RHE). In our case, as the potential increases to 1.4 V vs RHE (close to the onset potential for OER), two new peaks appear at 360 and 660 cm −1 , which can be assigned to the twist and stretch vibrations of Ir−O−Ir (Ir >4+ ), respectively.…”