Amorphous Mo-doped NiS0.5Se0.5 Nanosheets@Crystalline NiS0.5Se0.5 Nanorods for High Current-density Electrocatalytic Water Splitting in Neutral Media

It is vitally important to develop highly active, robust and low-cost transition metal-based electrocatalysts for overall water splitting in neutral solution especially at large current density. In this work, amorphous Mo-doped NiS0.5Se0.5 nanosheets@crystalline NiS0.5Se0.5 nanorods (Am-Mo-NiS0.5Se0.5) was synthesized using a facil one-step strategy. In phosphate buffer saline solution, the Am-Mo-NiS0.5Se0.5 shows tiny overpotentials of 48 and 209 mV for hydrogen evolution reaction (HER), 238 and 514 mV for oxygen evolution reaction (OER) at 10 and 1000 mA cm(-2), respectively. Moreover, Am-Mo-NiS0.5Se0.5 delivers excellent stability for at least 300 h without obvious degradation. Theoretical calculations revealed that the Ni sites in the defect-rich amorphous structure of Am-Mo-NiS0.5Se0.5 owns higher electron state density and strengthened the binding energy of H2O, which will optimize H adsorption/desorption energy barriers and reduce the adsorption energy of OER determining step.

Automated summary

It is essential to develop inexpensive and efficient transition metal based electrocatalysts for neutral water splitting. This work successfully synthesized amorphous Mo-doped NiS0.5Se0.5 nanosheets@crystalline NiS0.5Se0.5 nanorods through a simple one-step strategy. The Am-Mo-NiS0.5Se0.5 catalyst showed low overpotentials for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), and exhibited excellent stability for at least 300 hours. Theoretical calculations revealed that the defect-rich amorphous structure of Am-Mo-NiS0.5Se0.5 enhanced H2O binding energy and optimized the energy barriers for H adsorption/desorption and OER determining step.