Enhancing Voltage Reversal Tolerance of Proton Exchange Membrane Fuel Cells by Tuning the Microstructure of IrO_x Catalysts

Abstract

Voltage reversal of proton exchange membrane fuel cells caused by hydrogen deficiency seriously deteriorates the anodes and lowers their performance and lifetime. A commonly used method is to add oxygen evolution reaction catalysts (e.g., IrO 2 ) to the anode to extend the water electrolysis plateau against harmful carbon corrosion. Herein, strongly connected IrO x nanoparticles (SC-IrO x ) are prepared by removing the low surface area carbon carrier of the as-synthesized Ir/C catalyst. The reversal-tolerant anode with SC-IrO x owns an anti-reversal time of 9.32 h, which is 3.2 and 4.4 times that of the reversal-tolerant anode with commercial IrO x and weakly connected IrO x , respectively. Further transmission electron microscope characterizations reveal that SC-IrO x can construct a stable electron and proton transport pathway in the anode catalyst layer, which can delay the isolation of oxygen evolution reaction catalyst from the electron and proton conducting network, thus extending the water electrolysis plateau. Herein, our findings suggest that tuning the microstructures of IrO x catalysts is indeed an effective and promising approach to extend the water electrolysis plateau and alleviate the performance degradation of proton exchange membrane fuel cells during the voltage reversal process.

Constructing highly durable reversal-tolerant anodes via integrating high-surface-area Ti4O7 supported Pt and Ir@IrOx for proton exchange membrane fuel cells

“…3h and Table S2 (ESI †), the combination of low Ir loading, long reversal time, and slow performance degradation achieved by the Ir@IrO x /Pt/Ti 4 O 7 is comparable to, and in some cases even surpasses, those reported for recent RTAs. 5,14,19,[25][26][27][28][29][30][31][32][33][34][35][36][37][38]…”

Review of carbon-support-free platinum and non-platinum catalysts for polymer electrolyte fuel cells: will they feature in future vehicles?

“…Therefore, attempts have been made to reduce Ir loading in RTAs through means such as the use of IrO 2 /RuO 2 composite, 178,179 PtRu alloy, 180,181 and Co-doped PtRu alloy 182 OER catalysts, with the support of carbon black or graphitized carbon black. Furthermore, the effects of the crystallinity, preferred orientation of IrO x , 183 and microstructure of IrO x , 184 on cell reversal performance have been reported. When (1) these modified composite or alloy OER catalysts 178–182 are supported on Pt/Ti 4 O 7 or other Pt/oxides and/or (2) properties of IrO x 183,184 in Ir@IrO x /Pt/Ti 4 O 7 without carbon supports are tuned, the Ir loading may be reduced.…”

“…Furthermore, the effects of the crystallinity, preferred orientation of IrO x , 183 and microstructure of IrO x , 184 on cell reversal performance have been reported. When (1) these modified composite or alloy OER catalysts 178–182 are supported on Pt/Ti 4 O 7 or other Pt/oxides and/or (2) properties of IrO x 183,184 in Ir@IrO x /Pt/Ti 4 O 7 without carbon supports are tuned, the Ir loading may be reduced. Two-dimensional transition metal carbides, known as MXenes, with a composition of Ti 3 C 2 T z were recently used as supports for Pt particles in PEFC anodes, where T z is the surface terminal group (typically –O, –OH, or –F).…”