Copper-molybdenum sulfide and phosphide electrodes for superior energy storage and conversion

Ternary transition metal sulfide (TTMS) and ternary transition metal phosphide (TTMP) based materials have received great attention as materials for energy storage and generation devices due to several advantages, such as high electrical conductivity, abundant active sites, and synergetic effects between each transition metal. In this project, the copper-molybdenum sulfide and phosphide materials were designed via facile hydrothermal technique and successive hydrothermal and phosphatization methods, respectively. The coppermolybdenum sulfide and phosphide have cotton-like morphology and each electrode showed high electrochemical energy storage and conversion properties. The electrodes displayed high areal-specific capacitance of 3.5 and 5.2 F/cm2 at the current density of 3 mA/cm2. In addition, compared to the first cycle performance, the electrodes exhibited specific capacitance retention of 86.9 and 69.4 % with ~ 100% coulombic efficiency after 4,000 cycles. Moreover, the copper-molybdenum sulfide and phosphide electrodes showed superior catalytic activities and stability towards overall water splitting. Each electrode required the low HER overpotential of 207 mV and 147 mV at 10 mA/cm2 and showed the Tafel slope of 118 and 109 mV/dec, respectively. Furthermore, to obtain the current density of 10 mA/cm2, OER overpotential of 270 mV and 213 mV was necessary, along with a Tafel slope of 82 and 48 mV/dec. Also, the excellent catalytic performance of all electrodes was observed by the comparison of 1st vs 1k activity and 40 hours chronoamperometry measurements. Based on the electrochemical performance, copper-molybdenum sulfide and phosphide can be effective materials for superior energy storage and conversion