Phase-Controlled Synthesis of 2H/3R-MoSe₂ Nanosheets on P-Doped Carbon for Synergistic Hydrogen Evolution

The nanoscale structure of catalysts has a profound influence on their physicochemical properties. However, the controlled synthesis of desired highly active microstructures is still challenging. In this work, through the introduction of phytic acid (PA), MoSe2 nanosheets with 2H/3R heterophases are successfully synthesized on a P-doped carbon substrate. Plenty of defects are introduced into the basal plane of MoSe2 with largely expanded interlayer spacings, which increase the number of active sites and enhance the electronic/ionic transport and mass transfer. Benefiting from these structure merits, the obtained heterostructure exhibits superior HER activity and durability. A low overpotential of 164 mV is observed at a current density of 10 mA cm–2 with a Tafel slope of 44 mV dec–1. The HER performance is well maintained even after 10 h tests, showing superior electrochemical robustness. This controlled synthesis 2H/3R heterophased MoSe2 can be extended to other transitional metal chalcogenides (TMDs) for diverse applications.