Metal Phthalocyanine-Porphyrin-based Conjugated Microporous Polymer-derived Bifunctional Electrocatalysts for Zn-Air Batteries.

Conjugated microporous polymers (CMPs) as emerging porous materials with diverse structures and tunable building-units have attracted much attention in the electrochemical field. Herein, we designed phthalocyanine-porphyrin-based conjugated microporous polymers as precursors for fabrication of Co, Fe, N tri-doped graphene composites towards oxygen reduction and evolution reaction (ORR/OER). As expected, the elements cobalt and iron are well dispersed in graphene carbon and interact with the nitrogen sites, thereby providing extra electrocatalytic active sites and enhancing its overall conductivity. Benefiting from its unique design and structure, the obtained catalyst affords a superior bifunctional catalytic activity with a positive onset potential of 0.957 V for ORR, and a low overpotential of 0.36 V for OER. More attractively, the CoFeNG is employed as an air cathode catalyst in Zn-air batteries, showing a maximum current density of 215 mA cm-2 and good cycle stability for 20000 s. The rational design of phthalocyanine-porphyrin-based derivatives provides a feasible route for the construction of high-performance ORR/OER catalysts.

Multi-heteroatom-doped dual carbon-confined Fe3O4 nanospheres as high-capacity and long-life anode materials for lithium/sodium ion batteries.

The lithium/sodium-ion storage properties of transition metal oxides often undergo startling volume variation and poor electrical conductivity. Herein, N, P and S doped dual carbon-confined Fe3O4 nanospheres (Fe3O4@C@G) are prepared by the multi-heteroatom-doped dual carbon-confined strategy. The first carbon layer results from multi-heteroatom-containing polymer derived N, P and S doped carbon to form Fe3O4@doped carbon core-shell nanostructure. And the second carbon layer results from the further encapsulated reduced graphene oxide (rGO) to form Fe3O4@doped carbon@graphene 3D architecture (Fe3O4@C@G). As expected, the resulting Fe3O4@C@G can be served as the universal anode materials towards lithium/sodium-ion batteries (LIBs/SIBs). Interestingly, Fe3O4@C@G delivers higher reversible capacity of 919 mAh g-1 at 0.1 A g-1 for LIBs. As for SIBs, Fe3O4@C@G also shows a high reversible capacity of 180 mAh g-1 after 600 cycles at 0.1 A g-1. Furthermore, the electrochemical reaction kinetics in LIBs/SIBs are investigated and Li+ full cells are also assembled to demonstrate its practical application.