Isolated Pt atoms tethered to N-doped MoSx as highly efficient and sustainable hydrogen evolution reaction electrocatalyst

In this work, synergistic NH4+ intercalation and nitrogen-containing molecule doping realize a crystalline-to-amorphous (i.e., MoSx) structure transition with enhanced HER reactivity and superior stability obtained via structural distortion and abundant active sites. The applied N dopants partially replace the bridging S22− and form Mo-N bonds, where the alkyl N-dopant tetramethylammonium chloride (TEA) achieves the most effective doping. The HER activity increases with an increasing number of bridging S22− and MoⅤ species, both of which contribute to advance electrocatalytic performance. Furthermore, N-doped MoSx is identified as an exceptional stabilizing platform to anchor single Pt atoms (PtSA) through Pt-S bonding, rendering MoSx/TEA/PtSA a highly promising electrocatalyst. MoSx/TEA/PtSA achieved comparable performance to that of the benchmark Pt/C catalyst (i.e., a cathodic current density of 10 mA·cm−2 at overpotential of 97 mV) with much lower loading of Pt (0.67 wt%). Theoretical calculations based on density functional theory indicate that Pt atoms and Pt-adjacent sulfur atoms act as active sites. The superior interfacial electron transfer and thus HER performance of MoSx/TEA/PtSA arises from (1) boosted electronic metal-support interaction through Pt-S bonds and (2) enhanced H adsorption ability of Pt-adjacent sulfur atoms due to Pt coordination.