Impact of d-Band Occupancy and Lattice Contraction on Selective Hydrogen Production from Formic Acid in the Bimetallic Pd₃M (M = Early Transition 3d Metals) Catalysts

Catalysts that are highly selective and active for H₂ production from HCOOH decomposition are indispensable to realize HCOOH-based hydrogen storage and distribution. In this study, we identify two effective routes to promoting the Pd catalyst for selective H₂ production from HCOOH by investigating the effects of early transition metals (Sc, Ti, V, and Cr) incorporated into the Pd core using density functional theory calculations. First, the asymmetric modification of the Pd surface electronic structure (dz² vs d_yz + d_zx) can be an effective route to accelerating the H₂ production rate. Significant charge transfer from the subsurface Sc atom to the surface Pd atom and subsequent extremely low level of d band occupancy (2 storage and distribution economically feasible.