Effect of Se content on the oxygen evolution reaction activity and capacitive performance of MoSe₂ nanoflakes

In this work, a facile and cost-effective method is proposed to synthesize ultrathin MoSe₂ nanoflakes. To get high purity MoSe₂ nanoflakes, the reaction parameters are optimized. The TEM and Raman analysis confirmed the formation of few-layered MoSe₂ nanoflakes consisting of 2 to 3 layers. The influence of Se content on the OER and capacitive performance of MoSe₂ are studied in detail. The catalyst with optimal electrochemical performance (MS1.8) shows outstanding OER activity and capacitive performance. It requires a low overpotential of only 320 mV to reach a current density of 10 mA cm⁻² with a low Tafel slope of 45.3 mV dec⁻¹. Also, it exhibited a specific capacity of 25 mAh g⁻¹ at a current density of 1 A g⁻¹. The excellent OER activity of the MoSe₂ nanoflakes can be attributed to the few-layered structure, which provides a high electrochemical surface area. Moreover, the prepared MoSe₂ nanoflakes show excellent cyclic stability up to 5000 CV cycles. Our findings indicate that the amount of Se in MoSe₂ plays a significant role in achieving maximum electrochemical performance from MoSe₂. The method used in this study may provide a low-cost and simple technique to synthesize non-noble MoSe₂ for a wide-scale application.