Engineering S, N-doped carbon nanosheets derived from thiazolothiazole-based conjugated polymer for efficient electrocatalytic oxygen evolution and Zn-air battery

Electrochemical oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) by using metalfree electrocatalysts is an emerging research interest for clean energy due to its cost affordability and eco-friendliness. However, only a few metal-free electrocatalysts are reported to exhibit robust OER and ORR performances, although OER and ORR are very important in various energy technology like metalair batteries, fuel cells, etc. Herein, we have developed a rigid thiazolo [5,4-d] thiazole-based organic conjugated polymer, P-TzTz, and its polymer-derived N and S-doped carbon nanosheets for metal-free electrocatalytic OER and ORR. The polymer possesses a unique two-dimensional nanosheet structure with a moderate surface area of 72.6 m2/g and a wide range of pore sizes. The synthesized P-TzTz displayed a reasonable electrocatalytic OER performance with excellent long-term stability. The OER performance was further enhanced by pyrolyzing the P-TzTz at 800 & DEG;C to prepare the N and S-doped carbon nanosheet, P-TzTz-CNS80 0. The elevated surface area (228 m2/g) with uniform mesopores, enhanced electrical conductivity of P-TzTz-CNS80 0, and the presence of N, and S as the dopants for improving active sites made the P-TzTz-CNS80 0 a promising OER/ORR electrocatalyst as it showed the OER overpotential of 347 mV@10 mA/cm2 current density with more than 45 h long-range durability and 98% Faradic efficiency of oxygen evolution. Finally, to utilize the good OER efficacy of P-TzTz-CNS80 0-based metal-free electrocatalyst, a rechargeable Zn-air battery was fabricated as a proof of concept by taking P-TzTz-CNS80 0 as the air cathode. The Zn-air battery revealed a constant open circuit potential of 1.44 V and high charging/discharging stability over 40 h with a minimal loss in round trip frequency. Thus, the report corroborates the promising potential of P-TzTz derived N and S-doped carbon nanosheets as an efficient metal-free electrocatalyst as an air cathode for Zn-air battery for clean energy conversion.& COPY; 2023 Elsevier Ltd. All rights reserved.