Coordinated Co-NC/CoFe Dual Active Centre Embedded Three-dimensional Ordered Macroporous Framework as Bifunctional Catalyst for Efficient and Stable Zinc-Air Batteries

Developing efficient and stable multifunctional electrocatalyst is very important for zinc-air batteries in practical. Herein, semiconductive spinel CuFe2O4 supported Co-N co-doped carbon (Co-NC) and CoFe alloy nanoparticles were proposed. In this strategy, the three-dimensional ordered macroporous CuFe2O4 support provides rich channels for mass transmission, revealling good corrosion resistance and durability at the same time. ZIF-67 derived Co-NC decoration improves the conductivity of the catalyst. Further, the uniformlydistributed Co-NC and CoFe nanoparticles (C/CF) dramatically promote the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) performance. Accordingly, C/CF@CuFe2O4 catalyst shows remarkable bifunctional electrocatalytic activity, with an ORR half-wave potential of 0.86 V, and an OER over-potential of 0.46 V at 10 mA cm-2. The zinc-air battery using this catalyst exhibits a power density of 95.5 mW cm-2 and a durable cyclability for over 170 h at a current density of 10 mA cm-2, which implies a great potential in practical application.

A conductive and ordered macroporous structure design of titanium oxide-based catalytic cathode for lithium-sulfur batteries

The application of lithium-sulfur (Li-S) batteries is hindered by the insulating characteristic of sulfur and slow reaction kinetics of lithium polysulfides. Here, we propose a three-dimensionally ordered macroporous (3DOM) structured conductive polar Ta-doped TiO2 framework with supported Co active site (CoTa@TiO2)to enhance the conversion kinetics of polysulfides. The 3DOM structure serves as an efficient sulfur host for the active sulfur through abundant pores and adsorption site. At the same time, the macropores can buffer the volume expansion of sulfur and enlarged mass transfer. The strong electrostatic attraction between Ti-O bond and polysulfide also promotes the adsorption of polysulfides. Moreover, the doped-Ta improves the conductivity of TiO2 by narrowing the band gap, whereas the supported Co can accelerate the catalytic transformation. Benefited from advanced structural designandsynergistic effect of Co and Ta doped TiO2, the Li-S cell with 3DOM CoTa@TiO2 cathode exhibits an impressive areal capacity of 3.4 mAh cm-2 under a high sulfur loading of 5.1 mg cm-2. This work provides an alternative strategy for the development of carbon-based cathode materials for lithium-sulfur batteries.