Interatomic Spacing-Dependent Electrocatalytic CO₂ Reduction: Inert Te Heteroatom Modulation in Hexagonal Pd...

Metallic interatomic spacing emerges as a key activity descriptor in electrocatalysis, yet achieving angstrom-level precision in its dynamic modulation and establishing definitive structure-activity correlations persist as critical bottlenecks. Here, we developed a phase-controlled strategy enabling continuous interatomic spacing modulation in a library of hexagonal Pd-Te nanoplates (NPs), where various atomically ordered intermetallic phases from cubic Pd₄Te to rhombohedral Pd₂₀Te₇/Pd₈Te₃ and hexagonal PdTe₂ were synthesized, realizing precise tuning of adjacent Pd-Pd distances (d_Pd-a-Pd) from 2.75 to 4.07 Å. The proof-of-concept electrochemical CO₂ reduction (ECR) for CO formation displayed a volcano-shaped dependence on d_Pd-a-Pd, where Pd₂₀Te₇ NPs with a d_Pd-a-Pd of 2.88 Å exhibited a maximal CO Faraday efficiency (FE_CO) of 99.9%, and preserved FE_CO over 90% at ∼120 mA cm^-2 during long-term stability. Integrated in situ spectra and theoretical calculations confirmed the dominated distance effect over electronic effect, and revealed that increasing d_Pd-a-Pd upshifted d-band center toward the Fermi level while altering *CO adsorption configuration from strongly bound *CO_T to weakly bound *CO_L, resulting in exceptional ECR activity and CO anti-poisoning capacity on Pd₂₀Te₇ NPs owing to the optimally balanced *COOH adsorption and *CO desorption. This study underscores the pivotal role of interatomic spacing in regulating intermediate adsorption configurations for electrocatalysis.