Unravelling the strong metal-support interaction between Ru quantum dots and g-C3N4 for visible-light photocatalytic nitrogen fixation

Abstract

Abstract Renewable ammonia production technologies based on clean energy are highly expected, especially photocatalytic nitrogen fixation. Strong metal-support interaction (SMSI) usually occurs between the transition metal and the support, and enhances the activity and stability of the catalysts. In this paper, it is found that the strong interaction between Ru quantum dots and g-C3N4 nanosheets significantly improves the photocatalytic nitrogen fixation performance. A series of catalysts with different Ru loadings (1\u2009wt.%, 3\u2009wt.% and 5\u2009wt.%) were prepared. Due to the SMSI, Ru quantum dots (∼3\u2009nm) do not agglomerate, and the electron transfer from g-C3N4 to Ru leads to the formation of more Ru°. These factors are responsible for better and more stable performances of the photocatalytic reduction of N2 to NH3 in water compared to pure g-C3N4. The ammonia production rate over the as-synthesized RuCN-3 catalyst is 20.55\u2009μmol\u2009g−1\u2009h−1 in the absence of sacrificial agent in a nitrogen atmosphere. It should be noted that SMSI can also protect active sites, thus significantly improve their catalytic stability. By solving the energy band structure, the reaction mechanism of photocatalytic nitrogen fixation was explained. This study provides a promising and sustainable strategy for photocatalytic nitrogen fixation.