Atomically Dispersed Ru-Decorated TiO2 Nanosheets for Thermally Assisted Solar-Driven Nitrogen Oxidation into Nitric Oxide

Abstract

Thermally assisted photodriven nitrogen oxidation to nitric oxide (NO) using air as a reactant is a promising way to supersede the traditional NO synthesis industry accompanied by huge energy expenditure and greenhouse gas emission. Meanwhile, breaking the N≡N triple bond (941 kJ·mol−1) in nitrogen is still challenging, and the development of more efficient catalysts is necessary. Herein, Ru single atoms decorated TiO2 nanosheets (Ru SAs/TiO2) were constructed and achieved superior performance for NO photosynthesis with a product rate of 192 μmol g−1 h−1 and a quantum efficiency of 0.77% at 365 nm. Both 15N isotope labeling experiments and in situ near ambient pressure X-ray photoelectron spectroscopy (in situ NAP-XPS) proved the origin of NO from N2 photooxidation. A series of in situ characterizations and theoretical calculations unveiled the reaction pathway of nitrogen photooxidation. Breaking the O-O bond to form (N-O)2-Ru intermediates was demonstrated as the rate-determining step. Importantly, a single-atomic structure was proven to inhibit the aggregation and inactivation of Ru, leading to outstanding durability.