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The selective conversion of dilute NO pollutant into low-toxic product and simultaneous storage of metabolic nitrogen for crop plants remains a great challenge from the perspective of waste management and sustainable chemistry. This study demonstrates that this bottleneck can be well tackled by refining the reactive oxygen species (ROS) on Ni-modified NH 2 -UiO-66(Zr) (Ni@NU) using nickel foam (NF) as a three-dimensional (3D) substrate through a flow photoanode reactor via the gas-phase photoelectrocatalysis. By rationally refining the ROS to * OH, Ni@NU/NF can rapidly eliminate 82 % of NO without releasing remarkable NO 2 under a low bias voltage (0.3 V) and visible light irradiation. The abundant mesoporous pores on Ni@NU/NF are conducive to the diffusion and storage of the formed nitrate, which enables the progressive conversion NO into nitrate with selectivity over 99 % for long-term use. Through calculation, 90 % of NO could be recovered as the nitrate species, indicating that this state-of-the-art strategy can capture, enrich and recycle the pollutant N source from the atmosphere. This study offers a new perspective of NO pollutant treatment and sustainable nitrogen exploitation, which may possess great potential to the development of highly efficient air purification systems for industrial and indoor NO x control.

Designing adsorption materials with high adsorption capacities and selectivities is highly desirable for precious metal recovery. Desorption performance is also particularly crucial for subsequent precious metal recovery and adsorbent regeneration. Herein, a metalorganic framework (MOF) material (NH 2 -UiO-66) with an asymmetric electronic structure of the central zirconium oxygen cluster has an exceptional gold extraction capacity of 2.04 g g À 1 under light irradiation. The selectivity of NH 2 -UiO-66 for gold ions is up to 98.8 % in the presence of interfering ions. Interestingly, the gold ions adsorbed on the surface of NH 2 -UiO-66 spontaneously reduce in situ, undergo nucleation and growth and finally achieve the phase separation of highpurity gold particles from NH 2 -UiO-66. The desorption and separation efficiency of gold particles from the adsorbent surface reaches 89 %. Theoretical calculations indicate that -NH 2 functions as a dual donor of electrons and protons, and the asymmetric structure of NH 2 -UiO-66 leads to energetically advantageous multinuclear gold capture and desorption. This adsorption material can greatly facilitate the recovery of gold from wastewater and can easily realize the recycling of the adsorbent.

Gold and palladium are the most widely used precious metal materials in the field of electronic devices and industrial catalysis. How to realize the green recycling of gold and palladium is important and challenging. In this work, we found that gold and palladium in wastes, such as electronic devices and industrial catalysts, can be completely dissolved and recycled by photocatalysis. Gold and palladium are oxidized to the ionic state in water, which does not involve strong acids, strong alkalis, toxic cyanides, or an organic medium. More interestingly, the dissolution of gold and palladium in different halogen aqueous solutions has special selectivity, which depends on the coordination stability constants between gold and palladium with halide ions. Therefore, gold and palladium can be selectively dissolved in iodine ion solution and bromine ion solution, respectively, then gold and palladium can be obtained by a one-step reduction. This work opens up a new direction for optimizing the photocatalytic dissolution technology and promoting the green recycling of precious metals.