Progress and Perspective for In Situ Studies of Oxygen Reduction Reaction in Proton Exchange Membrane Fuel Cells

Abstract

Proton exchange membrane fuel cell (PEMFC) is one of the most promising energy conversion devices with high efficiency and zero emission. However, oxygen reduction reaction (ORR) at the cathode is still the dominant limiting factor for the practical development of PEMFC due to its sluggish kinetics and the vulnerability of ORR catalysts under harsh operating conditions. Thus, the development of high-performance ORR catalysts is essential and requires a better understanding of the underlying ORR mechanism and the failure mechanisms of ORR catalysts with in situ characterization techniques. This review starts with the introduction of in situ techniques that have been used in the research of the ORR processes, including the principle of the techniques, the design of the in situ cells, and the application of the techniques. Then the in situ studies of the ORR mechanism as well as the failure mechanisms of ORR catalysts in terms of Pt nanoparticle degradation, Pt oxidation, and poisoning by air contaminants are elaborated. Furthermore, the development of high-performance ORR catalysts with high activity, anti-oxidation ability, and toxic-resistance guided by the aforementioned mechanisms and other in situ studies are outlined. Finally, the prospects and challenges for in situ studies of ORR in the future are proposed.

Influence of Defects on Barrier Energy Formation for OOH* Intermediate in ORR on Tetragonal-ZrO2 with Adsorbed-Hydroxyl

“…This allows us to investigate how defects influence charge distribution during the breaking of the O−H bond in the OH group and the formation of the OO−H bond in the OOH* intermediate. Tables 3−5 provide a summary of some selected E (2) energies and interaction types for the OH + O 2 reaction on Zr sites at the GGA:BLYP level for the final states of the hydroxylated pristine t-ZrO 2−x and t-ZrO 2−x N x , respectively. Correspondingly, Tables S2−S4 provide these data for the transition states.…”

A networked iron and nitrogen-doped ZIF-8/MWCNTs heterostructure for oxygen reduction reaction

“…1 Among them are proton-exchangemembrane fuel cells (PEMFCs)-electrochemical gadgets that transform chemical power into electricity, which have been widely studied since they have low operating temperatures, high conversion efficiency, and no emissions. 2 The performance of PEMFCs is posed by the intrinsically sluggish kinetics of the oxygen reduction reaction (ORR). 3 The ORR process has two pathways: 4 in the 4e − ORR pathway, O 2 is directly reduced to H 2 O and in the 2e − ORR pathway, O 2 is partially reduced to H 2 O 2 or further reduced to H 2 O.…”

Interface Engineering for the Enhanced Antipoisoning Property of Oxygen Reduction Reaction

“…Direct methanol (CH 3 OH) fuel cells (DMFCs), a device that converts the chemical energy of CH 3 OH into electrical energy, have high energy density and power density, making them an attractive power source for portable electronic devices and fuel cell vehicles. − As the cathode reaction of DMFCs, oxygen reduction reaction (ORR) plays a vital part in the contribution of device performance. − So far, palladium (Pd)-based materials are widely used in an alkaline environment as high-performance ORR electrocatalysts. However, in the DMFCs, CH 3 OH and the reaction intermediate CO from the anode will reach the cathode through the proton exchange membrane, resulting in the poisoning phenomenon of Pd-based catalysts. − This behavior would seriously reduce the service life of Pd-based electrocatalysts, leading to the actual working efficiency being much lower than the theoretical expectation.…”