Efficient Solar Driven Upgrading of N₂ to Urea Through Photoredox Reactions on Pt Cluster/TiO₂

Synthetic nitrogen fertilizers, such as urea, are instrumental in augmenting agricultural output and addressing the demands of a growing population. Nevertheless, conventional urea production heavily relies on energy-intensive processes. In this study, an environmentally friendly photocatalytic method is proposed for directly and selectively synthesizing urea from nitrogen (N-2) and methanol (CH3OH using a Pt cluster-decorated TiO2 catalyst (Pt cluster/TiO2). Remarkably, the Pt cluster/TiO2 exhibits outstanding urea synthesis performance with a rate of 105.68 mu mol g(-1) h(-1) and N-selectivity of 97.29 +/- 0.79%, representing the highest level of photocatalytic urea synthesis from N-2. Further analysis with density functional theory (DFT) calculation reveals that the "sigma-pi*" donor-acceptor interaction occurred between Pt clusters and N-2, efficiently reducing the N-2 hydrogenation barrier. EPR experiments demonstrate that photogenerated electrons (e(-)) and hole (h(+)) are synchronously consumed through N-2 reduction and CH3OH oxidation, thereby accelerating urea synthesis. The crucial step of C & horbar;N coupling is initiated by the reaction between *NH & horbar;NH and *CHO intermediate, facilitated by the low energy barrier on Pt cluster/TiO2. This work suggests an mild route of urea production and provides profound insights into the underlying chemistry of the C & horbar;N coupling reaction, which can guide the sustainable synthesis of essential indispensable chemicals.