Size Effects of MoS2 on Hydrogen and Oxygen Evolution Reaction

Abstract

Molybdenum disulfide (MoS 2 ) has been widely used as a catalyst for the bifunctional activities of hydrogen and oxygen evolution reactions (HER and OER). Here, we investigated size dependent HER and OER performance of MoS 2 . The smallest size (90 nm) of MoS 2 exhibits the lowest overpotential of -0.28 V at -10 mAcm -2 and 1.52 V at 300 mAcm -2 with the smallest Tafel slopes of 151 and 176 mVdec -1 for HER and OER, respectively, compared to bigger sizes (2 µm and 6 µm) of MoS 2 . The better HER and OER performance is attributed to high electrochemical active surface area (6 × 10 -4 cm 2 ) with edge sites and low charge transfer resistance (18.1 Ω), confirming that the smaller MoS 2 nanosheets have the better catalytic behavior.