2024-01-04 ジョージア工科大学
◆1つの論文では、窒素、水、炭素、光が触媒と相互作用して、通常の方法よりもはるかにエネルギーを少なく使用する環境温度と圧力でアンモニアを生成する方法が解明されています。
◆もう1つの論文では、安定した触媒が廃棄物の化肥を無害な窒素に変換し、将来的に新しい肥料を作るために使用できる可能性があります。
◆これらのプロセスにはまだ多くの作業が残っていますが、これらは成長する世界の人口のニーズを満たしながら、より持続可能な循環に向けた一歩であると述べられています。
＜関連情報＞
- https://coe.gatech.edu/news/2024/01/photochemistry-and-new-catalyst-could-make-fertilizer-more-sustainable
- https://pubs.acs.org/doi/10.1021/jacsau.3c00556
- https://pubs.acs.org/doi/10.1021/acsenergylett.3c01672
照明下における酸化チタン上の炭素誘導窒素中心ラジカルの生成 Formation of Carbon-Induced Nitrogen-Centered Radicals on Titanium Dioxide under Illumination
Po-Wei Huang, Nianhan Tian, Tijana Rajh, Yu-Hsuan Liu, Giada Innocenti, Carsten Sievers, Andrew J. Medford, and Marta C. Hatzell
Journal of the American Chemical Society Au Published:November 27, 2023
DOI:https://doi.org/10.1021/jacsau.3c00556
Abstract
Titanium dioxide is the most studied photocatalytic material and has been reported to be active for a wide range of reactions, including the oxidation of hydrocarbons and the reduction of nitrogen. However, the molecular-scale interactions between the titania photocatalyst and dinitrogen are still debated, particularly in the presence of hydrocarbons. Here, we used several spectroscopic and computational techniques to identify interactions among nitrogen, methanol, and titania under illumination. Electron paramagnetic resonance spectroscopy (EPR) allowed us to observe the formation of carbon radicals upon exposure to ultraviolet radiation. These carbon radicals are observed to transform into diazo- and nitrogen-centered radicals (e.g., CHxN2• and CHxNHy•) during photoreaction in nitrogen environment. In situ infrared (IR) spectroscopy under the same conditions revealed C–N stretching on titania. Furthermore, density functional theory (DFT) calculations revealed that nitrogen adsorption and the thermodynamic barrier to photocatalytic nitrogen fixation are significantly more favorable in the presence of hydroxymethyl or surface carbon. These results provide compelling evidence that carbon radicals formed from the photooxidation of hydrocarbons interact with dinitrogen and suggest that the role of carbon-based “hole scavengers” and the inertness of nitrogen atmospheres should be reevaluated in the field of photocatalysis.
選択的で安定した電気化学的硝酸還元反応のための原子配列PdCu電極触媒 Atomically Ordered PdCu Electrocatalysts for Selective and Stable Electrochemical Nitrate Reduction
Jeonghoon Lim, David A. Cullen, Eli Stavitski, Seung Woo Lee, and Marta C. Hatzell
ACS Energy Letters Published:October 19, 2023
DOI:https://doi.org/10.1021/acsenergylett.3c01672
Abstract
Electrochemical nitrate reduction (NO3 RR) has attracted attention as an emerging approach to mitigate nitrate pollution in groundwater. Here, we report that a highly ordered PdCu alloy-based electrocatalyst exhibits selective (91% N2), stable (480 h), and near complete (94%) removal of nitrate without loss of catalyst. In situ and ex situ XAS provide evidence that structural ordering between Pd and Cu improves long-term catalyst stability during NO3RR. In contrast, we also report that a disordered PdCu alloy-based electrocatalyst exhibits non-selective (44% N2 and 49% NH4+), unstable, and incomplete removal of nitrate. The copper within disordered PdCu alloy is vulnerable to accepting electrons from hydrogenated neighboring Pd atoms. This resulted in copper catalyst losses which were 10× greater than that of the ordered catalyst. The design of stable catalysts is imperative for water treatment because loss of the catalyst adds to the system cost and environmental impacts.
