Stable and Efficient PtRu Electrocatalysts Supported on Zn-BTC MOF Derived Microporous Carbon for Formic Acid Fuel Cells Application.

Inayat Ali Khan,Muhammad Sofian,Amin Badshah,Muhammad Imran,Muhammad Abdullah Khan,Muhammad Arif Nadeem

doi:10.3389/fchem.2020.00367

Abstract

Highly efficient, well-dispersed PtRu alloy nanoparticles supported on high surface area microporous carbon (MPC) electrocatalysts, are prepared and tested for formic acid oxidation reaction (FAOR). The MPC is obtained by controlled carbonization of a zinc-benzenetricarboxylate metal-organic framework (Zn-BTC MOF) precursor at 950°C, and PtRu (30 wt.%) nanoparticles (NPs) are prepared and deposited via a polyol chemical reduction method. The structural and morphological characterization of the synthesized electrocatalysts is carried out using powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), an energy dispersive X-ray (EDX) technique, and gas adsorption analysis (BET). The FAOR performance of the catalysts is investigated through cyclic voltammetry (CV), chronoamperometry (CA), and electrochemical impedance spectroscopy (EIS). A correlation between high electrochemical surface area (ECSA) and high FAOR performance of the catalysts is observed. Among the materials employed, Pt1Ru2/MPC 950 with a high electrochemical surface area (25.3 m2 g−1) consequently showed superior activity of the FAOR (Ir = 9.50 mA cm−2 and Jm = 2,403 mA ) at room temperature, with improved tolerance and stability toward carbonaceous species. The superior electrochemical performance, and tolerance to CO-poisoning and long-term stability is attributed to the high surface area carbon support (1,455 m2 g−1) and high percentage loading of ruthenium (20 wt.%). The addition of Ru promotes the efficiency of electrocatalyst by offering FAOR via a bifunctional mechanism.

Highlights

Direct formic acid fuel cells (DFAFCs) have gained extensive attention during the last two decades, serving as future clean energy due to their numerous benefits such as high energy density, low flux of crossover, environmental friendliness, and non-flammable properties (Chen et al, 2011; Fu et al, 2015)
DFAFCs practical realization is partly hindered by insufficient durability and a high cost barrier associated with platinum, even though it has been proven that Pt is the most efficient and stable electrocatalyst (Benipal et al, 2017; Xu et al, 2017a)
Skrabalak et al (2008) investigated, using a spectrophotometric method, that heating ethylene glycol in oxygen resulted to glycolaldehyde, a reductant capable of most noble metal’s reduction at a high temperature

Summary

Introduction

Direct formic acid fuel cells (DFAFCs) have gained extensive attention during the last two decades, serving as future clean energy due to their numerous benefits such as high energy density, low flux of crossover, environmental friendliness, and non-flammable properties (Chen et al, 2011; Fu et al, 2015). We uncover that catalysts with a PtRu atomic ratio of 1:2 follow a direct oxidation pathway of FAOR and presented high specific, mass activities and stability.

Results

Conclusion