Defective g-C 3 N 4 optimizes phosphate distribution in the catalytic layer and boosts the performance of high-temperature proton exchange membrane fuel cells

Phosphoric acid (PA) is a vital proton-conducting medium for high-temperature proton exchange membrane fuel cells (HT-PEMFCs); however, regulating its distribution to decrease poisoning on the electrocatalysts and maintain elevated reactivity durability remains a significant challenge. In this work, defective g-C 3 N 4 (D-C 3 N 4 ) was incorporated into Pt/C catalyst layers to promote PA distribution for enhancing the intrinsic reactivity expression of catalysts. Following decoration of D-C 3 N 4 , HT-PEMFCs with low Pt loading in both the anode (0.20 mg Pt cm −2 ) and the cathode (0.40 mg Pt cm −2 ) exhibited a high peak power density of 672 mW cm −2 and excellent high reactivity durability (above 620 mW cm −2 ) after accelerated 3500 cycles, which is far superior to previously published results. This work first reveals that the acid/base interaction of D-C 3 N 4 with PA modulates PA distribution in the catalytic layer, thereby enhancing the intrinsic reactivity expression and utilization efficiency of catalysts in HT-PEMFCs.