Chloride ion (Cl) is one of the most common anions in the aqueous environment. A mathematical model was developed to determine and quantify the impact of Cl on the oxidization rate of organic compounds at the beginning stage of the UV/persulfate (PS) and UV/HO processes. We examined two cases for the UV/PS process: (1) when the target organic compounds react only with sulfate radicals, the ratio of the destruction rate of the target organic compound when Cl is present to the rate when Cl is not present (designated as r/ r) is no larger than 1.942%; and (2) when the target organic compounds can react with sulfate radicals, hydroxyl radicals and chlorine radicals, r/ r, can be no larger than 60%. Hence, Cl significantly reduces the organic destruction rate in the UV/PS process. In the UV/HO process, we found that Cl has a negligible effect on the organic-contaminant oxidation rate. Our simulation results agree with the experimental results very well. Accordingly, our mathematical model is a reliable method for determining whether Cl will adversely impact organic compounds destruction by the UV/PS and UV/HO processes.
Graphene/hexagonal boron nitride (h‐BN) monolayer in‐plane heterostructure offers a novel material platform for both fundamental research and device applications. To obtain such a heterostructure in high quality via controllable synthetic approaches is still challenging. In this work, in‐plane epitaxy of graphene/h‐BN heterostructure is demonstrated on Cu–Ni substrates. The introduction of nickel to copper substrate not only enhances the capability of decomposing polyaminoborane residues but also promotes graphene growth via isothermal segregation. On the alloy surface partially covered by h‐BN, graphene is found to nucleate at the corners of the as‐formed h‐BN grains, and the high growth rate for graphene minimizes the damage of graphene‐growth process on h‐BN lattice. As a result, high‐quality graphene/h‐BN in‐plane heterostructure with epitaxial relationship can be formed, which is supported by extensive characterizations. Photodetector device applications are demonstrated based on the in‐plane heterostructure. The success will have important impact on future research and applications based on this unique material platform.
Photodissociation dynamics of o-nitrophenol in the gas phase at different photolysis wavelengths (361-390 nm) is investigated, and the nascent OH radical is observed by the single-photon laser-induced fluorescence technique. At all the photolysis wavelengths, the OH radicals are formed in vibrationally cold state (upsilon(")=0) and have similar rotational state distributions. The average rotational temperature for all the photolysis wavelengths is approximately 970+/-120 K, corresponding to a rotational energy of 1.9+/-0.2 kcal mol(-1). The spin orbit and Lambda-doublet states of the OH fragments formed in the dissociation are measured to have nonstatistical distributions. To get an insight into the dissociative mechanism leading to OH formation in the photolysis of o-nitrophenol, the potential energy surfaces of the OH-forming channels are mapped by ab initio theoretical calculations. According to both experimental and theoretical results, a possible mechanism for OH formation is proposed.
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