Nitrogen monoxide (NO), a critical precursor to particulate matter with an aerodynamic diameter ≤ 2.5 μm (PM_2.5) and ozone formation, requires efficient abatement at atmospheric low concentrations (< 1 ppm), yet conventional photocatalysts struggle with deep NO purification due to inefficient trace O₂/NO co-activation. Herein, we engineer Fe single atoms on defective TiO₂ catalyst (Fe_SA/OV-TiO₂, OV refers to oxygen vacancy) with orbital-modulated dual-active sites. Density functional theory calculations and in situ characterizations reveal that surface oxygen vacancies drive robust O₂ activation to generate reactive oxygen species (ROS). Adjacent Fe single atoms enable targeted NO chemisorption via their d-orbital hybridization with antibonding π* orbital of NO. This synergy shifts the NO oxidation pathway from ·O₂⁻-dominated Eley–Rideal (E–R) to dual-activated Langmuir–Hinshelwood (L–H) pathways, where pre-adsorbed NO directly reacts with ROS, forming thermodynamically stable bidentate nitrate. Crucially, Fe_SA/OV-TiO₂ achieves 75% NO conversion efficiency with 98% nitrate selectivity under visible light irradiation, outperforming defective TiO₂-OV by 1.4-fold while maintaining the good activity over five cycles without deactivation. The work establishes orbital-level dual-site engineering as a strategy for developing high-efficiency photocatalysts for air pollution remediation.

Environmental deterioration, especially water pollution, is widely dispersed and could affect the quality of people's life at large. Though the sewage treatment plants are constructed to meet the demands of cities, distributed treatment units are still in request for the supplementary of centralized purification beyond the range of plants. Electrochemical degradation can reduce organic pollution to some degree, but it has to be powered. Triboelectric nanogenerator (TENG) is a newly-invented technology for low-frequency mechanical energy harvesting. Here, by integrating a rotary TENG (R-TENG) as electric power source with an electrochemical cell containing a modified graphite felt cathode for hydrogen peroxide (H₂O₂) along with hydroxyl radical (·OH) generation by Fenton reaction and a platinum sheet anode for active chlorine generation, a self-powered electrochemical system (SPECS) was constructed. Under the driven of mechanical energy or wind flow, such SPECS can efficiently degrade dyes after power management in neutral condition without any O₂ aeration. This work not only provides a guideline for optimizing self-powered electrochemical reaction, but also displays a strategy based on the conversion from distributed mechanical energy to chemical energy for environmental remediation.