Progress has been made in the study of the mechanism of single-atom interface activation of ozone

Catalytic ozone oxidation is an effective method for deep removal of organic pollutants in wastewater, but its interfacial catalytic mechanism is not clear. Recently, the team of Cao Hongbin, a researcher at the Institute of Process Engineering of the Chinese Academy of Sciences, developed a series of graphitic carbon nitride single-atom catalysts supported with cobalt, manganese and nickel transition metals, which accelerate the decomposition of ozone (O3) and produce highly active hydroxyl radicals (·· OH)。 Based on density functional theory simulation and in situ X-ray absorption spectroscopy, the adsorption configuration of intermediate products in the process of single-atom interface ozone activation is proposed. Effect of OH and pollutant reaction interval. The study was recently published in Environmental Science & Technology.

Organic wastewater pollution seriously threatens human health and ecological balance, and efficient reduction of refractory organic matter in external wastewater has become a major technical demand for current water pollution control. Strong oxidation based on in situ generation · OH, catalytic ozone oxidation can remove refractory organic pollutants in industrial wastewater, and the properties of the catalytic active site determine the efficiency and generation of O3 activation. Mechanism and kinetics of OH and other reactive oxygen species. But how the current active site interacts with O3 and · The generation path of OH is still controversial, which limits the development and design of efficient catalysts. In addition, in water treatment applications, the catalyst surface or the bulk solution in the control of · The OH reaction interval reduces the effective quenching of free radicals, but determines · The exact nature of the catalyst in which OH attacks the reaction interval of the contaminant remains unknown.

The research team studied the mechanism of ozone activation by a series of carbon nitride-supported single-atom catalysts M1-C3N4 (M=Co, Mn, Ni). The experimental results show that the MN4 locus · The main path for OH generation is O3→ Oads→ *OO→ · O3- → · OH, while the catalytic activity of M1-C3N4 in degrading oxalic acid is Co1-C3N4>Mn1-C3N4>Ni1-C3N4. Among them, Ni1-C3N4 activity was the lowest, which was related to the low activity of subsequent intermediates on the active site. The oxygen binding energy is higher on Mn1-C3N4, so the intermediate product *OO is adsorbed in Griffiths configuration on metal atoms, and this double Mn-O bond causes the Mn site to form saturation coordination, so · OH attacks organic matter mainly in aqueous solutions. For the CoN4 site, the adsorption of *OO on metal Co is in a Pauling configuration (single Co-O bond), and the unsaturated coordination Co site allows further adsorption of contaminants, so · OH attack on oxalic acid can occur simultaneously on the surface of Co1-C3N4 and in the main aqueous solution, which is the reason why its catalytic ozone oxidation performance is better than that of Mn1-C3N4.


Adsorption configuration of O3 activation intermediate products at different MN4 sites and corresponding · OH oxidation interval plot from the paper

PhD student Wang Jing is the first author of the paper, and researcher Cao Hongbin is the corresponding author. The above research work was supported by the National Natural Science Foundation of China (51934006) and the State Key Laboratory of Vanadium and Titanium Resources Comprehensive Utilization (2021P4FZG04A). (Source: Liu Runan, China Science News)

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