Optimal MEA structure and operating conditions for fuel cell reactors with hydrogen peroxide and power cogeneration

Abstract

The cogeneration of hydrogen peroxide (H _2 O _2 ) and power in proton exchange membrane fuel cell (PEMFC) reactors via two-electron oxygen reduction reaction on the cathode is an economical, low-carbon, and green route for the on-site production of H _2 O _2 . However, in practice, the H _2 O _2 that cannot be collected timely will accumulate and self-decompose in the catalyst layer (CL), reducing the H _2 O _2 generation efficiency. Thus, accelerating the mass transport of H _2 O _2 within the cathode CL is critical to efficient H _2 O _2 generation in PEMFC. Herein, we investigated the effects of the membrane electrode assembly (MEA) fabrication process, cathode CL thickness, and cathode carrier water flow rate on H _2 O _2 generation and cell performance in a PEMFC reactor. The results show that the catalyst-coated membrane-type MEA exhibits high power output due to its lower proton transport resistance. However, the formed CL with a dense structure significantly limits H _2 O _2 collection efficiency. The catalyst-coated gas diffusion electrode (GDE)-type MEA formed macroporous structures in the cathode CL, facilitating carrier water entry and H _2 O _2 drainage. In particular, carbon cloth GDE with thin CL could construct rich macroscopic liquid channels, thus maximizing the generation of H _2 O _2 , but will impede fuel cell performance. These results suggest that the construction of a well-connected interface between CL and proton exchange membrane (PEM) in MEA and the establishment of a macroscopic pore structure of the CL are the keys to improve the cell performance and H _2 O _2 collection efficiency.

Keywords

• hydrogen peroxide
• electrochemical synthesis
• PEM fuel cell
• PGM-free catalysts
• 2e-ORR
• catalyst layer structure