Interfacial bond endowing FeS2/Bi2S3 composites superb OER performance

Abstract

Developing high-efficient main group element Bismuth-based OER electrocatalysts is of great significance to sustainable energy storage and conversion. However, they still suffer from structural deficiencies such as poor electroconductivity, lack of active sites and high absorption energy barriers. Constructing Fe-contained Bismuth-based compounds is regarded as an effective strategy to ameliorate the above deficiencies. In this study, core-shell structured FeS2/Bi2S3 composites are achieved successfully with solvothermal and sulfurization method by constructing interfacial bond Bi–S–Fe. Through in-depth analysis, we confirm that the interfacial chemical bond Bi–S–Fe, act as a bridge to the linkage of FeS2 and Bi2S3, enhance electron transport efficiency and hydrophilicity by regulating charge ordering. Moreover, the proportion of metal active centers (Fe3+, Fe2+, Bi3+, Bi2+) with different absorption/desorption energy could also be modulated by Bi–S–Fe, thus endowing FeS2/Bi2S3 composites a superb OER performance. As expected, FeS2/Bi2S3-0.33 shows ultralow overpotentials of 313 and 419 mV at current densities of 10 and 100 mA cm−2, respectively, and a Tafel slope as low as 25 mV dec−1, which outperforms most of Bismuth-based and even noble/transition metal-based electrocatalysts. This work may shed light on construction of interfacial bond for rational design of high-performance OER catalysts.