Cobalt-silver dual sites promote highly selective photocatalytic NO removal via synergy of internal electric field integrated plasmon and spin polarization effect.

Nitrogen oxides (NOx), primarily NO from high-temperature fuel combustion, pose serious threats to ecological and human health. Photocatalysis offers a solar-driven approach for NO oxidation, but often leads to toxic NO2 byproduct due to insufficient active sites and reactive oxygen species (ROS). In this study, the tri-synergetic photocatalyst was developed that integrated the internal electric field (IEF) of AgCl/ZnSn(OH)6 heterojunction, the surface plasmon resonance (SPR) effect of Ag nanoparticles and the spin polarization effect of Co clusters to realize the rapid separation and transport of photogenerated charges. Experimental and theoretical calculations confirmed that IEF promotes the directional migration of electrons, Ag nanoparticles extends visible light absorption and increases charge density through the SPR effect, and Co clusters acts as electron trap facilitating interfacial transfer after illumination. The Co clusters also caused spin polarization effect to promote exciton separation and became an activation center that enhanced the adsorption and activation of O2 and H2O to promote the generation of ROS, and also promote the adsorption and activation of NO to become the intermediate NO-, which could quickly react with ROS to generate NO3- by one step, suppressing the release of NO2 toxic byproducts. The charge transport mechanism and activation mechanism of the tri-synergistic photocatalyst have important reference significance for the design of photocatalyst for efficient removal of air pollutants.