Synthesis and Advanced Electrochemical Characterization of Multifunctional Electrocatalytic Composite for Unitized Regenerative Fuel Cell

Abstract

A multifunctional electrocatalytic composite was synthesized for use as a generic catalytic material in the polymer electrolyte membrane (PEM) type reactors, working in either fuel cell, direct methanol fuel cell, or electrolyzer mode. It is constructed from graphene sheets evenly covered with TiON x on which PtCu, Ir, and Ru nanoparticles are immobilized. It enables high performances for oxygen reduction, hydrogen and methanol oxidation, and also hydrogen and oxygen evolution. Its activity is either higher or comparable to the monofunctional benchmark catalysts, namely, Pt, PtRu, and Ir nanoparticles. An important part of this study is the advanced electrochemical degradation investigation. With the use of an electrochemical flow cell coupled to ICP-MS and combining these results with identical location electron microscopy, we reveal not only potential shortcomings but also opportunities for our material. As a result, we also put forward general guidelines for the appropriate use of multifunctional electrocatalysts.

Ir/TiONx/C high-performance oxygen evolution reaction nanocomposite electrocatalysts in acidic media: synthesis, characterization and electrochemical benchmarking protocol

“…This could be due to the dissolution of Ir. It is known that Ir dissolves via transient dissolution when oxides are formed, however notably more when reduced [35][36][37]. Thus, going to a lower potential limit involves the potential degradation of the catalyst before the activity evaluation.…”

“…The first activation consisted of fast cycling (300 mV s −1 ) between 0.45 and 1.45 V versus reversible hydrogen electrode (RHE). The lower potential limit (LPL) was chosen so as to avoid a complete reduction of Ir-oxide, which is known to trigger Ir dissolution [35][36][37]. The upper potential limit (UPL) limit was ca.…”

Oxygen vacancies engineering by coordinating oxygen-buffering CeO2 with CoO nanorods as efficient bifunctional oxygen electrode electrocatalyst

“…Due to the tremendous demand for energy and the degradation of environment, unified regenerative fuel cell (URFC) is emerging as one of the most efficient energy storage and conversion technologies bringing together fuel cell and electrolyzer components [1][2][3][4][5][6]. The performance of the URFC heavily depends on the fundamental oxygen electrode reactions involving the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), which generates electric power at the cathode and stores chemical energy at the anode, respectively [7][8][9][10].…”

Bifunctional Pt-IrO2 Catalysts for the Oxygen Evolution and Oxygen Reduction Reactions: Alloy Nanoparticles vs. Nanocomposite Catalysts

“…33 More recently also composite materials are discussed. 34 One of the main challenges for employing URFCs are the stability requirements 35 of the catalyst at these harsh conditions changing from oxidative to reductive conditions.…”