Efficient Photocatalytic Nitrogen Fixation: Enhanced Polarization, Activation, and Cleavage by Asymmetrical Electron Donation to N(sic)N Bond

Photocatalytic nitrogen (N-2) fixation suffers from low efficiency due to the difficult activation of the strongly nonpolar N(sic)N bond. In this study, a Ru-Co bimetal center is constructed at the interface of Ru/CoSx with S-vacancy on graphitic carbon nitride nanosheets (Ru-Vs-CoS/CN). Upon adsorption, the two N atoms in N-2 are bridged to the Ru-Co center, and the asymmetrical electron donation from Ru and Co atoms to N-2 adsorbate highly polarized N(sic)N bond to double bond order. The plasmonic electric-field-enhancement effect enables the Ru/CoSx interface to boost the generation of energetic electrons. The Schottky barrier between Ru and CoSx endows the interface with electron transfer from CoSx to Ru. The Ru-end bound N at the Ru-Co center is preferentially hydrogenated. As a result, the Ru-Vs-CoS/CN photocatalyst shows an NH3 production rate of up to 0.438 mmol g(-1) h(-1), reaching a high apparent quantum efficiency of 1.28% at 400 nm and solar-to-ammonia efficiency of 0.042% in pure water under AM1.5G light irradiation.