Defective g-C3N4 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-C3N4 (D-C3N4) was incorporated into Pt/C catalyst layers to promote PA distribution for enhancing the intrinsic reactivity expression of catalysts. Following decoration of D-C3N4, 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-C3N4 with PA modulates PA distribution in the catalytic layer, thereby enhancing the intrinsic reactivity expression and utilization efficiency of catalysts in HT-PEMFCs.