Hydrothermal synthesis of N-doped RGO/MoSe₂ composites and enhanced electro-catalytic hydrogen evolution

A facile two-step hydrothermal approach is adopted to synthesize MoSe₂/N-doped RGO (NG) composites with the N/C atomic percentage changing from 1.13 to 5.16 at%. In the composites, nanoclusters of MoSe₂ nanosheets are dispersed on plicated NG nanosheets. The electrochemical measurement suggests that the MoSe₂/NG composites exhibit enhanced electro-catalytic HER activity as compared to MoSe₂ and MoSe₂/RGO. Moreover, as the N/C ratio of NG is increased, the activity of MoSe₂/NG increases firstly and then decreases. At low N/C ratio, the impact of interfacial energy barrier between MoSe₂ and NG is negligible and the electron transfer is substantial, so the activity of the MoSe₂/NG composites increases with carrier concentration in NG. However, at high N/C ratio, the energy barrier blocks the electron transfer from NG to MoSe₂ remarkably. Consequently, the MoSe₂/NG composites with an intermediate N/C ratio have the highest activity. Owing to the synergistic effect of NG and MoSe₂, the Tafel slope of the composites is reduced from 114.69 to 78.45 mV dec⁻¹ by 32% as compared to pure MoSe₂. The results provide us valuable information for efficient design of transition metal dichalcogenide catalysts for electro-catalytic hydrogen evolution.