Al-MOF-derived porous carbon-modified Pt/C catalyst for constructing a high-performance super fuel cell via an ORR + EDLC parallel-discharge mechanism

Abstract

In order to reduce the high polarization caused by the hysteresis effect of O₂ diffusion and boost the power density of oxygen cathodes under a transient heavy load, an Al-MOF-derived porous carbon-modified Pt/C catalyst is proposed as a new capacitive ORR catalyst to construct super fuel cells (SFCs) via an ORR + EDLC dual-discharge parallel process. Herein, a capacitive porous carbon material (BTCC-2) with a large specific surface area (SSA) and high graphitization was synthesized via one-step carbonization of Al-MOFs (Al-BTC). After compounding BTCC-2 with commercial Pt/C catalysts, electrochemical tests were performed and revealed that the composite with 40% BTCC-2 provided the highest transient discharge performance. Moreover, the composite had a higher onset potential and limiting current density (5.236 mA cm⁻²) than Pt/C and a half-wave potential (0.833 V) comparable to that of Pt/C. The abundant pore structure and large surface of BTCC-2 greatly increased the interaction between oxygen and the catalyst surface. Besides, the contained BTCC-2 serve as a significant power bank to remarkably buffer and relieve the rapidly decreasing output voltage under an instant heavy load owing to the oxygen deficiencies in a Zn–air battery through the ORR + EDLC dual-parallel-discharge process. The proposed SFC design has potential as a universal method to solve the sluggish ORR process and provide high transient power density for fuel cell-driven vehicles.