Oxygen evolution reaction activity of carbon aerogel supported Pd–Ni–Al catalysts synthesized by microwave irradiation method

Abstract

The oxygen evolution reaction (OER) is a critical step for oxygen production during the electrochemical splitting of water. Effective OER catalysts support the development of clean energy technologies by increasing the energy efficiency of these processes. In this study, carbon aerogel (CA) was first synthesized as a catalyst support material using sol-gel, supercritical drying, and pyrolysis process. Then, mono-metallic (Pd/CA, Al/CA), bi-metallic (Pd–Al/CA, Pd–Ni/CA), and tri-metallic (Pd–Ni–Al/CA) catalysts were synthesized by microwave irradiation method. Inductively coupled plasma-mass spectrometry (ICP-MS), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy have been made to examine the structural properties of the synthesized catalysts. Electrochemical analysis was carried out through cyclic voltammetry (CV), chronoamperometry, and electrochemical impedance spectroscopy (EIS) in alkaline media (1 M KOH: Methanol) to examine the effect of metal loading of CA support material towards OER performance. All the compositions showed excellent activity toward OER, among all Pd–Ni/CA catalysts showed the highest activity. The OER peak current increased remarkably up to 48 mA cm−2 with methanol addition, which signifies the substantial application of carbon aerogel supported-Pd-Ni-Al catalysts in direct methanol fuel cells (DMFCs). Pd–Ni/CA display high OER performance with maximum diffusion coefficient, Do (6.6 × 10−8 cm2 s−1) and heterogeneous rate constant, ko (4.706 × 10−4 cm s−1), and smaller value of Tafel slope (128 mV dec−1). Electrochemical studies predicted that all the prepared carbon aerogel supported-Pd-Ni-Al catalysts can be used as efficient catalysts for OER and other related electrocatalysis applications.