Atomically dispersed Fe-Cu dual-site catalysts synergistically boosting oxygen reduction for hydrogen fuel cells.

Atomically dispersed FeCu-NC catalyst containing FeN 4 and CuN 4 dual active sites is synthesized, and the assembled hydrogen fuel cell of using FeCu-NC as cathode presents a ultrahigh peak power density. DFT calculations reveal that the strain effect from the CuN 4 species efficiently tailors the electronic structure of FeN 4 species and therefore boost its catalytic activity. [Display omitted] • Atomically dispersed FeCu-NC catalyst containing FeN 4 and CuN 4 dual active sites is synthesized. • The FeCu-NC exhibits better ORR performance than commercial Pt/C and Fe-N-C single-atom catalyst in alkaline medium. • Using FeCu-NC as cathode, the assembled hydroxide exchange membrane fuel cell presents a ultrahigh peak power density. • DFT calculations reveal that the synergistical effect of FeN 4 and CuN 4 species efficiently boosts the ORR. Compared to most popular single-atom catalysts (SACs), the dual-atom catalysts may possess better catalytic performance due to the synergistic effect of dual-atom sites. However, revealing the synergistic mechanism of dual-atom sites to improve catalytic activity is still insufficient. Here, atomically dispersed FeCu-NC catalyst containing FeN 4 and CuN 4 dual active sites is synthesized, and has been identified by high angle annular dark-field STEM and X-ray absorption spectroscopy. The as-synthesized FeCu-NC exhibits a half-wave potential of 0.882 V, which is nearly 40 mV superior to Pt/C catalyst and 24 mV better than Fe-NC SAC in alkaline medium. Using FeCu-NC as a cathode catalyst, the assembled hydroxide exchange membrane fuel cell presents a peak power density of 0.91 W·cm−2, which is ∼ 21% higher than of Fe-NC based one (0.76 W·cm−2). DFT calculations reveal that the strain effect caused by the CuN 4 species replacing the neighbor carbon environment of the FeN 4 species, can efficiently tailor the electronic structure and reduce the OH* adsorption on FeN 4 species and therefore improves the catalytic activity and kinetic process of ORR. This work provides a new insight into the synergistic catalysis of dual-atom sites for ORR. [ABSTRACT FROM AUTHOR]