Fe7S8/FeS2/C as an efficient catalyst for electrocatalytic water splitting

Exploring effective bi-functional catalysts is of great significance to enhance the electrochemical activity for overall water splitting. To date, Fe7S8 has been rarely reported to realize electrochemical overall water splitting because of its intrinsic poor conductivity. In this paper, Fe7S8/FeS2 heterostructured nanosheets with interface structures and defect sites are prepared via a facile hydrothermal method. Fe7S8/FeS2/C electrocatalysts are constructed through the addition of carbon powder to weaken the electron transfer barrier. As expected, Fe7S8/FeS2/C requires the overpotential of 262 mV and 198 mV to reach 10 mA/cm2 toward oxygen evolution reaction and hydrogen evolution reaction, respectively. Moreover, Fe7S8/FeS2/C attains a voltage of 1.67 V at 10 mA/cm2 and maintains long-term stability for 24 h toward overall water splitting in a two-electrode system. The excellent activity can be related to interface structures and surface defect sites, which boost the charge transfer rate owing to the rich active sites.