In-situ growth of ZnS/FeS heterojunctions on biomass-derived porous carbon for efficient oxygen reduction reaction

Abstract

Abstract It is an urgent task to develop highly efficient non-noble metal electrocatalysts in the direction of ORR, but still a huge and long-term challenge. Herein, an efficient one-step pyrolysis of Sichuan pepper powder, 2,2-bipyridine, FeCl3, NaSCN, and ZnCl2 at 900 °C provides the FeS/ZnS@N,S-C-900 hybrid catalyst. Transmission electron microscopy (TEM) images and Mott-Schottky curves clearly reveal the in-situ constructed abundant FeS/ZnS-based p-n junctions dispersed on the biomass-derived porous carbon surface of FeS/ZnS@N,S-C-900. The as-prepared FeS/ZnS@N,S-C-900 hybrid exhibits superior ORR performance in comparison with Pt/C in 0.1 M KOH with high onset (Eonset) and half-wave potentials (E1/2) of 1.00 and 0.880 V vs. RHE, large limiting current density (JL) of 5.60 mA cm−2, and robust durability and methanol tolerance. Impressively, upon the light irradiation, FeS/ZnS@N,S-C-900 produces a photocurrent as high as ca. 0.3 μA cm−2, resulting in further improvement over Eonset, E1/2, and JL of FeS/ZnS@N,S-C-900 to 1.10 V vs. RHE, 0.885 V vs. RHE, and 6.02 mA cm−2. Experiment in combination with theoretical calculations demonstrate the significant effect of FeS/ZnS heterojunction on the enhanced ORR catalytic activity of FeS/ZnS@N,S-C-900. This work is useful for the development of advanced heterojunction-based ORR catalysts for various energy conversion devices.