Atom-Scale Dispersed Palladium in a conductivePd0.1TaS2 Lattice with a Unique Electronic Structurefor Efficient Hydrogen Evolution

摘要

Noble metal catalysts have extraordinary catalytic activity but suffer from high cost; therefore single atom catalysis attracts tremendous attention. Here, we propose atom-scale dispersed palladium (Pd) in a layered TaS_2 lattice to form new compounds of Pd_xTaS_2, whose crystal structure was resolved by powder X-ray diffraction. The electrical conductivity of metallic Pd_(0.1)TaS_2 (1.36 * 10~4 S m~(-1)) is twice as large as that of TaS_2 (6.18 * 10~3 S m~(-1)). This compound applied as a new electrocatalyst for the hydrogen evolution reaction (HER) exhibits excellent catalytic performance with an onset overpotential of 77 mV, superior to those of other catalysts such as TaS_2 (295 mV) and Pd-loaded TaS_2 (114 mV). Density functional theory calculations reveal that the interaction of Pd-4d and Ta-5d orbitals results in the upshift of the Fermi level (TaS_2 versus Pd_(0.1)TaS_2) to decrease the barrier height for the HER. Furthermore, the hybridization of Pd-4d and S-3p orbitals builds up pathways along the c axis to improve the conductivity and promote HER performance. It is noted that the amount of Pd used in Pd_(0.1)TaS_2 is only 4 wt%, compared with 20 wt% in commercial Pd/C catalysts, which is beneficial for its practical application.