Unconventional s-p-d hybridization in modulating frontier orbitals of carbonaceous radicals on PdBi nanosheets for efficient ethanol electrooxidation

Abstract

Rational design of highly efficient ethanol electrooxidation catalysts requires modulation of their band structure, yet most of the understanding stops at either upshift or downshift of d-band center that facilitates only a portion of ethanol oxidation reaction (EOR) process. Herein, we take in-situ formed carbonaceous intermediates as an essential part in regulating the band structure of 2D catalysts for the whole EOR process. We found that, by alloying Bi into Pd nanosheets, d band of Pd upshifted, resulting in the enhanced adsorption ability of the catalyst. After the adsorption of CH3CH2OH, p band of Bi dragged down d-band of Pd and lifted up s and p orbitals of the adsorbed carbonaceous radicals, forming molecular orbitals that bridged their energy gaps and lowered the energy barriers of electron transfer in C1 pathway. This unconventional s-p-d hybridization offers Pd14.9Bi nanosheets exhibit high mass activity of 6.6 A/mgpd and C1 selectivity of 19.7 %.