Highly Efficient Electrocatalyst of 2D-2D gCN-MoS Composites for Enhanced Overall Water Electrolysis.

For future clean and renewable energy technology, designing highly efficient and robust electrocatalysts is of great importance. Particularly, creating efficient bifunctional electrocatalysts capable of effectively catalyzing both hydrogen- and oxygen-evolution reactions (HERs and OERs) is vital for overall water electrolysis. In this study, we employ 2D molybdenum disulfide (MoS) nanosheets and pyrolytically fabricated 2D graphitic carbon nitride (gCN) nanosheets to create 2D gCN-decorated 2D MoS (2D-2D gCN-MoS) nanocomposites using a facile sonochemical method. The 2D-2D gCN-MoS nanocomposites show an interconnected and agglomerated structure of 2D gCN nanosheets decorated on 2D MoS nanosheets. For water electrolysis, the gCN-MoS nanocomposites exhibit low overpotentials (OER: 225 mV, HER: 156 mV), small Tafel slope values (OER: 49 mV/dec, HER: 101 mV/dec), and excellent durability (up to 100 h for both OER and HER) at 10 mA/cm in 1 M KOH. Furthermore, the gCN-MoS nanocomposites show excellent overall water electrolysis performance with a low full-cell voltage (1.52 V at 10 mA/cm) and outstanding long-term cell stability. The superb bifunctional activities of the gCN-MoS nanocomposites are attributed to the synergistic effects of 2D gCN (i.e., low charge-transfer resistance) and 2D MoS (i.e., a large electrochemically active surface area). These findings suggest that the 2D-2D gCN-MoS nanocomposites could serve as excellent bifunctional catalysts for overall water electrolysis.