Charge-Buffered Sulfidation Stabilized B^δ- in 1T MoS₂: Orbital Alignment for Efficient Alkaline Hydrogen Production.

Abstract

The sp³ hybridization of surface sulfur in metallic phase molybdenum disulfide (1T MoS₂) is identified as the intrinsic bottleneck for alkaline hydrogen production (HER), where their electron-saturated nature elevates the kinetic barrier for water dissociation. To overcome this limitation, a charge-buffered sulfidation strategy is reported to stabilize anionic boron (B^δ-) within 1T MoS₂. By employing molybdenum aluminum boride as the precursor, the B^δ- dopants can be efficiently preserved via the topological confinement imposed by Mo─B─Mo network. This approach also maintains the 1T phase integrity through Al-mediated electron compensation. Theoretical and experimental analyses reveal that B^δ- substitution generates vertically oriented empty p_z orbitals through sp² hybridization, which elevates orbital energy to align with molecular orbitals of water, significantly reducing the O─H cleavage barrier by over 80% compared to 1T MoS₂. Concurrently, the B─Mo─S networks upshift adjacent sulfur 3p band centers to optimize the hydrogen adsorption path. These dual functionalities endow the p_z-functionalized 1T MoS₂ with a low overpotential of -30 mV at 10 mA cm^-2, and high-current operation of 1 A cm^-2 at 1.779 V in an anion-exchange membrane electrolytic cell. This work not only establishes orbital alignment as a transformative design principle for advanced electrocatalysts, but also paves a novel synthetic pathway for 1T transition metal disulfides.