Spin Polarization Enhanced Photocatalytic N2 Reduction on Chiral Mesostructured Bi2WO6.

Harnessing the earth-abundant N2 via photocatalysis is a sustainable route to green NH3 synthesis. However, photocatalytic N2 reduction (PNR) remains constrained by the high energy barrier for N2 activation and reduction. In this work, we report that the spin-polarized chiral mesostructured Bi2WO6 (CMB) can facilitate the formation of metastable triplet NOH (3NOH) intermediates, while simultaneously promoting the separation and transport of photogenerated charge carriers, thereby enhancing PNR performance. The CMB was fabricated via a hydrothermal method using tartaric acid as a symmetry-breaking agent. Under sacrificial-agent-free conditions, the NH3 yield of 1325.5 μmol gcat-1 h-1 was achieved, representing a 4.7-fold enhancement over the best values reported for Bi- and W-based catalysts. The pronounced accumulation of the *NOH intermediate, a key precursor to NH3, is speculated to originate from the 3NOH intermediate, driven by the spin polarization of CMB. This work reveals the critical role of spin polarization in regulating triplet reaction intermediates and charge-carrier dynamics during N2 reduction, providing an effective strategy for the design of advanced photocatalysts for sustainable NH3 synthesis.