DUT-58 (Co) Derived Synthesis of Co Clusters as Efficient Oxygen Reduction Electrocatalyst for Zinc-Air Battery.

Lichao Gao,Shuai Chen,Quansheng Zhao,Dongjiang Yang,Rongsheng Cai,Xiaoliang Zhao

doi:10.1002/gch2.201700086

Abstract

To meet the requirement of fuel cells and metal–air batteries, non‐noble metal catalysts have to be developed to replace precious platinum‐based catalysts. Herein, Co nanoclusters (≈2 nm) are anchored on nitrogen‐doped reduced graphene oxide (Co/N‐r‐GO) by using DUT‐58 (Co) metal–organic framework and GO as precursors. Compared with single‐atom catalysts usually with ultralow concentration (<0.5 wt%), Co nanoclusters are more beneficial to break the O—O bond to ensure four electronic way for oxygen reduction reaction (ORR), since they can provide more adsorption centers for reactants. Therefore, as expected, the sample with 6.67 wt% Co content (Co/N‐r‐GO‐5%‐850) exhibits better ORR activity with a higher half‐wave potential of 0.831 V, a more positive onset potential of 0.921 V than Pt/C, and a comparable limiting current density in alkaline medium. The Co nanoclusters enhance the catalytic performance for ORR in three aspects: quantum size effects, metal–support interactions, and low‐coordination environment of metal centers. Furthermore, the sample is assembled into a zinc–air battery as the outstanding durable ORR catalyst. It displays a higher specific capacity (795 mAh g−1 at the current density 50 mA cm−2) and power density (175 mW cm−2) than Pt/C (731 mAh g−1 and 164 mW cm−2, respectively).

Highlights

The oxygen reduction reaction (ORR) has catalysts
The synthesis path to Co/N-reduced graphene oxide (r-GO)-850 is charted in Scheme 1, a series of catalysts with different GO contents (−2, −5, −10, and −15 wt%), Co/N-r-GO (−2, −5, −10, and −15%), were prepared from the mixture of DUT-58 and GO by a solvothermal and calcination process
The related K–L plots reveal the inverse current density (j−1) as a function of opposite of square root of rotating speed (ω−1/2) at different potential values. It represents a good linearity at different rotation speeds, and the n value is about 3.75 in the voltage range of 0.4–0.6 V, indicating the ORR process catalyzed by Co/N-r-GO-5%-850 is the four-electron transfer pathway

Summary

Full paper

DUT-58 (Co) Derived Synthesis of Co Clusters as Efficient Oxygen Reduction Electrocatalyst for Zinc–Air Battery. The Co nano clusters enhance the catalytic performance for ORR in three aspects: quantum Their high cost, the scarcity, and poor durability prevent large-scale practical application of business.[8,9,10] To overcome these problems, heteroatom S, N-doped or codoped carbon stuffs and transition metal based carbon materials as the electrocatalysts have been widely size effects, metal–support interactions, and low-coordination environment of metal centers. Anchoring MOF on GO and carbonizing can enhance the conductivity and meet the requirement.[21,22,23] Co-MOFs based on N, S, or other heteroatoms-containing ligands will generate cobalt based S, N, or other heteroatom doped carbon materials through the pyrolysis These will provide porous architecture, electric conductivity, and rich catalytic active sites, which all help the catalytic performance for ORR. Co/N-r-GO-5%-850 as the outstanding durable ORR catalyst for ZABs displays a higher specific capacity (795 mAh g−1) at the current density 50 mA cm−2 and power density (175 mW cm−2) than Pt/C (731 mAh g−1 and 164 mW cm−2, respectively)

Results and Discussion

Conclusion

Conflict of Interest