“…The Co 4 S 3 /Co 9 S 8 nanosheets with mixed crystal phases have been successfully prepared for the first time by using a solvent-thermal method with ultrasonic stripping technology. Fe-Co 4 S 3 /Co 9 S 8 nanosheets were formed after doping Fe 3+ ions by a one-step impregnation method, which showed excellent OER activity [51] .…”