The catalytic performance enhanced via π-electron cloud interaction of polymerized cobalt phthalocyanine/3D-graphene as bifunctional oxygen catalysts for Zn-air battery

• Published in: Journal of power sources 2023-02, Vol.556, p.232471, Article 232471
• Main Authors: Wang, Shuaifeng, Sun, Peng, Li, Na, Wang, Jigang, Zhang, Lei, Duan, Wenjie, Li, Zhongfang
• Format: Article
• Language: English
• Subjects: Bifunctional catalysts; Enhanced catalytic performance; Polymerized cobalt phthalocyanine; Three-dimensional graphene; Zn-air battery; π-π interaction
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2022.232471

The bifunctional oxygen catalysts are crucial to the commercialization of metal-air batteries. In this work, two-dimensional polymerized cobalt phthalocyanine (PPcCo) is combined with three-dimensional graphene (3D-G) through π-π interaction to obtain the PPcCo/3D-G bifunctional oxygen catalysts. The delocalized π-bonds of PPcCo provide greater electron delocalization energy. The π-π interaction between the PPcCo and 3D-G not only solidly anchors PPcCo and fully exposes the Co-N4 sites but also enhances the performance of the catalyst. The PPcCo/3D-G exhibits excellent electron conduction, a large specific surface area, and a rich pore structure for enhanced mass transfer. In terms of electrochemical performance, the oxygen reduction reaction (ORR) halfwave potential (E1/2) of PPcCo/3D-G catalytic is 0.860 V vs RHE and the electron transfer number of PPcCo/3D-G is 3.95 (@0.740 V vs RHE). The small overvoltage (ΔE = Ej = 10 - E1/2) of PPcCo/3D-G is 0.780 V. Furthermore, the Zinc-air battery (ZAB) with PPcCo/3D-G as the cathode catalyst has high power density (347 mW cm−2), specific capacity (776 mAh g−1), smaller charge/discharge polarization, and significant long-term stability. The flexible all-solid-state ZAB (FZAB) with PPcCo/3D-G as the cathode catalyst also exhibits excellent performance. These results suggest that the PPcCo/3D-G is available as an efficient cathode bifunctional catalyst for ZAB and FZAB. Poly (cobalt phthalocyanine) (PPcCo) was combined with three-dimensional graphene (3D-G) through π-π interaction to obtain PPcCo/3D-G with mesoporous structure, which exhibited excellent half-wave potential (0.860 V vs. RHE) and small overvoltage value (0.780 V) indicating that PPcCo/3D-G is an excellent bifunctional metal-air battery electrocatalyst. [Display omitted] •The PPcCo has a large conjugated structure and excellent thermal stability.•The π-π interaction between PPcCo and 3D-G enhances catalytic performance.•PPcCo/3D-G has a clearly defined catalytically active site of Co-N4 structure.•The ZABs with PPcCo/3D-G as cathode exhibit good charge/discharge performance.