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

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 CoIII have been constructed in a series of Pd-PdS2-Cox HNSs with tunable Co content. Experiments and theoretical calculations indicate that low-spin CoIII (t2g 6eg 0) with fully occupied t2g orbitals and empty d z 2 $d_{{z^2}}$ orbitals can accurately alter the d z 2 $d_{{z^2}}$ electron of Pd by σ-donation via the Co-S-Pd bridge. In contrast, the unfilled dxy orbital of high-spin CoIII (t2g 5eg 1) is essential for controlling the dxy electron of Pd via π-donation. Benefiting from d z 2 $d_{{z^2}}$ state optimization by σ-donation, Pd-PdS2-Co4.0 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.