Molybdenum disulfide with enlarged interlayer spacing decorated on reduced graphene oxide for efficient electrocatalytic hydrogen evolution

Layered transition metal dichalcogenides especially MoS2 is favorable to be the low-cost alternative to Pt-based electrocatalysts for water splitting. Defect-rich MoS2 nanosheets exhibiting enlarged interlayer spacing of 9.2 A were synthesized via a solvothermal method, in which trithiocyanuric acid (TTCA) was used as a sulfur source. In addition, we synthesized MoS2 with L-cysteine for comparison. To improve the conductivity and quantity of active exposed sites of MoS2 nanosheets, the rGO nanosheets were introduced to hybridize with MoS2. With the addition of rGO, the MoS2/rGO hybrids exhibit different morphologies and larger interlayer spacing of 9.5 A. Furthermore, the enhanced performance for hydrogen evolution reaction is attributed to the synergistic effect between the MoS2 nanosheets and rGO substrates. MoS2/rGO-2 possesses an onset overpotential of 118 mV, a small Tafel slope of 51 mV/dec, high double-layer capacitance (Cdl) of 15.27 mF/cm2, and superior cycling stability over 1000 cycles in acidic conditions.