Full-spectrum Radiation Research Articles

Z-scheme metal organic framework/Ag@AgCl heterojunction photocatalysts with elevated photocatalytic N2 fixation activity

As one of the most consumed chemical reagents, ammonia (NH3) has a wide range of applications in many fields. The demand for ammonia may continue to increase with the advancement of technology and the acceleration of industrialization. The traditional high energy consumption and high pollution ammonia synthesis methods (Haber-Bosch) need to be optimized and improved to reduce environmental pollution and energy dependence. In this work, a series of Z-scheme NM/Ag@AgCl heterojunctions were prepared as catalysts for the research of photocatalytic nitrogen fixation. By in-situ photodeposition, Ag@AgCl was uniformly distributed on the NM surface, and the interfaces of different substances were tightly bonded. The SPR effect that generated by Ag nanoparticles significantly enhanced the light energy absorption performance of heterojunction materials. In the ESR spectra, the signal peak intensity of NM/Ag@AgCl was higher than that of NM under light condition. Constructing of heterojunction was beneficial to the formation of Ti3+. The strong built-in electric field among NM and AgCl promoted the generation of Z-scheme heterojunction. NM/Ag@AgCl had sufficient redox potential to overcome thermodynamic barriers and drive the catalytic reaction. Without adding any sacrificial reagent, the ammonia production of NM/Ag@AgCl-3 reached 76.7 µmol g−1 h−1 under full spectrum radiation. The rate of ammonia formation of NM/Ag@AgCl was almost seven times than that of NM. The synergistic effect between NM and Ag@AgCl optimized the photogenerated carrier separation path. This work provided a new vision for the practical application of efficient photocatalytic N2 reduction.

Synergistic effect of bimetallic active sites on Ce doped NH2–MIL-125 for promoting photocatalytic conversion of nitrogen to NH3

Ammonia (NH3), one of the most abundant inorganic compounds in the world, is highly demanded in the international market. NH3 is mainly synthesized using Haber-Bosch technology, which severely pollutes the environment and consumes high quantities of energy. In this study, a series of Ce doped NH2–MIL-125 (Ce–NH2–MIL-125) was prepared using a one-step solvothermal method to assess the activity of photocatalytic nitrogen fixation. The applied light energy interval of Ce–NH2–MIL-125 was widened, and the establishment of a Ce–O–Ti chemical bond optimized the transport path of the photogenerated carriers. This excellent photoelectric performance represents a significant improvement in the separation capacity of the photogenerated electrons and holes in Ce–NH2–MIL-125. Doping with Ce resulted in the generation of dual active sites, Ti4+/Ti3+ and Ce4+/Ce3+, in NH2–MIL-125; additionally, the increase in the amount of Ti3+ was significantly higher than that of the initial NH2–MIL-125. The synergistic effect of the bimetallic active sites in Ce–NH2–MIL-125 accelerated the photocatalytic nitrogen fixation reaction. Under full spectrum radiation, the ammonia generation rate of NH2–MIL-125 was 10.6 µmol g−1 h−1. Ce–NH2–MIL-125–1.0 exhibited the highest capacity for nitrogen fixation; the highest ammonia formation rate was 39.4 µmol g−1 h−1. The photocatalytic activity of Ce–NH2–MIL-125–1.0 was 3.7 times higher than that of NH2–MIL-125. This study provides a reference for catalytic research on modified NH2–MIL-125.

Mechanisms of the emission of mercury from soil: Role of UV radiation

Light has been previously shown to play a role in the emission of mercury from soil; however, the mechanisms involved in this process are not well understood. In an effort to identify the wavelength of light that dominates this process, we conducted extensive laboratory studies of soil mercury flux using a dynamic flux chamber. Mercury fluxes were measured at constant temperature in the dark, under full spectrum radiation (λ = 320–700 nm) and under various radiation bands including 410–700 nm radiation, 320–580 nm radiation, and 320–380 nm radiation. Soil mercury emissions under full spectrum radiation were significantly elevated over dark fluxes in all trials. When UV light was removed from incident radiation (the λ = 410–700 nm condition), fluxes were not significantly different from dark fluxes in two of three trials. Soil fluxes under 320–580 nm radiation and 320–380 nm radiation were significantly elevated over dark fluxes in all trials and were related to radiation intensity in the UV region.

Effect of Radiation Quality on Growth and Photosynthesis of Acacia mangium Seedlings

Radiation quality was an important environmental cue to stimulate seed germination in Acacia mangium. The photo-synthetic CO2 assimilation rate, dark respiration rate, total biomass, and relative growth rate of seedlings grown under monochromatic radiation were significantly lower than those of seedlings grown under full spectrum radiation. Blue and red radiation induced shade-avoidance and shade-tolerant responses of A. mangium seedlings, respectively.