Enhancing C─C Bond Cleavage of Glycerol Electrooxidation Through Spin-Selective Electron Donation in Pd–PdS2–Cox Heterostructural Nanosheets

Abstract

As a 4d transition metal, the spin state of Pd is extremely difficult to directly regulate for the optimized d orbital states owing to the strong spin-orbit coupling effect and further extended d orbital. Herein, we devise a “spin-selective electron donation” strategy to tune specific d orbital electrons of Pd inspired by the Dewar−Chatt−Duncanson model theory. Co−S−Pd bridges with different spin-states of Co^III have been constructed in a series of Pd–PdS₂–Co_x HNSs with tunable Co content. Experiments and theoretical calculations indicate that low-spin Co^III (t_2g⁶e_g⁰) with fully occupied t_2g orbitals and empty $$ orbitals can accurately alter the $$ electron of Pd by σ-donation via the Co−S−Pd bridge. In contrast, the unfilled d_xy orbital of high-spin Co^III (t_2g⁵e_g¹) is essential for controlling the d_xy electron of Pd via π-donation. Benefiting from $$ state optimization by σ-donation, Pd–PdS₂–Co_4.0 delivers superior performance toward various bio-alcohols (ethanol, ethylene glycol, and glycerol) with enhanced C─C bond cleavage. Furthermore, coupling the glycerol oxidation reaction with the CO₂ reduction reaction (GOR||CO₂RR), the electricity consumption of GOR||CO₂RR drops 46.4% compared to the state-of-art system (OER||CO₂RR). Moreover, anodic Faraday efficiency (FE) of formic acid can be attainable at more than 90% at low voltage regions.