No abstract

Developing bifunctional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is essential for the development of zinc–air batteries (ZABs), but several challenges remain in terms of bifunctional activity. FeCo2S4/N-S-rGO was prepared by in situ homogeneous growth of bimetallic sulfide FeCo2S4 on N, S-doped reduced graphene oxide. FeCo2S4/N-S-rGO exhibits a half-wave potential of 0.89 V for ORR and an overpotential of 0.26 V at 10 mA cm−2 for OER, showing significantly bifunctional activity superior to Pt/C (0.85 V) and RuO2 (0.41 V). Moreover, the FeCo2S4/N-S-rGO assembled ZAB shows a superior specific capacity and a power density of 259.13 mW cm−2. It is demonstrated that the interfacial electron redistribution between FeCo2S4 nanoparticles and heteroatom-doped rGO matrix can efficiently improve the electrochemical performance of the catalyst. The results provide new insights into the preparation of high-capability composite catalysts combining transition metal sulfides with carbon materials for applications in ZABs.

The precise control of electronic configurations of catalytic sites via molecular engineering is significantly desirable for boosting electrocatalytic activity. We reported a new‐type composite electrocatalyst with cobalt phthalocyanine supported on N‐doped MXene nanosheets (N‐MXene/CoPc) through a self‐assembly process. Beneficial from the joint action of N sites participation and axial coordination, N‐MXene/CoPc exhibits a high ORR activity with positive onset potential (Eonset=0.98 V vs. RHE) and half‐wave potential (E1/2=0.863 V), which is superior over the pristine CoPc (E1/2=0.72 V) and the composite with undoped MXene as support (MXene/CoPc, E1/2=0.771 V). Additionally, N‐MXene/CoPc exhibits an excellent durability with only 8.5 % attenuation after 25000 s of continuous i‐t test, while a more obvious decay 18.6 % for 20 wt.% Pt/C. This work not merely reported a robust ORR catalyst, but more provides a reasonable design strategy for nonnoble‐metal catalysts through catalyst‐support interactions.