Few-layered MoSe₂ nanosheets with mixed 1T/2H phase were successfully arrayed on a Ti substrate (forming 1T@2H-MoSe₂/Ti) through a facile one-step solvothermal process. After testing different synthesis conditions, it was found that the optimal process involves a temperature of 200 ℃ and a reaction time of 12 h. Structural characterizations reveal that the morphology of 1T@2H-MoSe₂ consists of edge-terminated nanosheets with one to five layers, composed of a mixed 1T/2H phase dominated by the 1T one. The 1T@2H-MoSe₂/Ti electrode shows excellent HER catalytic activity, with a small onset potential (-120 mV vs. reversible hydrogen electrode, RHE) and an electrode potential of only -133 mV (vs. RHE) to achieve a current density of 20 mA·cm^-2. This excellent electrocatalytic activity is due to the synergistic effects of 1T metallic phase, few-layered nanosheet morphology, and direct growth of 1T@2H-MoSe₂on the Ti substrate. In addition, the 1T@2H-MoSe₂/Ti electrode shows excellent stability towards long-term electrolysis. This is due to the long-term stability of the valence states of Mo and Se, as shown by post-electrolysis X-ray photoelectron spectroscopy analysis.

The design of efficient artificial photosynthetic systems that harvest solar energy to drive the hydrogen evolution reaction via water reduction is of great importance from both the theoretical and practical viewpoints. Integrating appropriate co-catalyst promoters with strong light absorbing materials represents an ideal strategy to enhance the conversion efficiency of solar energy in hydrogen production. Herein, we report, for the first time, the synthesis of a class of unique hybrid structures consisting of ultrathin Co(Ni)-doped MoS₂ nanosheets (co-catalyst promoter) intimately grown on semiconductor CdS nanorods (light absorber). The as-synthesized one-dimensional CdS@doped-MoS₂ heterostructures exhibited very high photocatalytic activity (with a quantum yield of 17.3%) and stability towards H₂ evolution from the photoreduction of water. Theoretical calculations revealed that Ni doping can increase the number of uncoordinated atoms at the edge sites of MoS₂ nanosheets to promote electron transfer across the CdS/MoS₂ interfaces as well as hydrogen reduction, leading to an efficient H₂ evolution reaction.