<img src="Edit_bdc7d851-e537-40df-990c-d678defa9648.png" alt="" />(M = Au, Ag, Cu;<span lang="EN-US" style="font-size:9pt;font-family:"color:black;"><i>n&...<img src="Edit_bdc7d851-e537-40df-990c-d678defa9648.png" alt="" />(M = Au, Ag, Cu;<span lang="EN-US" style="font-size:9pt;font-family:"color:black;"><i>n</i></span>= 1, 2, 3) clusters were used as a cluster model to study the activation of oxygen molecules on single-atom catalysts. Structures of <img src="Edit_bb84deb7-e24a-4777-a2f6-a1621ddd2afc.png" alt="" /> clusters were studied by density functional calculations with global optimization. For each <span style="font-family:"color:black;white-space:normal;"><i>n</i></span>, the most stable structures are quite similar for different metal types, and the oxygen molecule prefers to be adsorbed onto M atoms. It is found that the activation degree of oxygen is higher on clusters with non-noble metal Cu than that of Ag or Au containing clusters, by comparing the changes of O-O bond length and vibrational frequency, natural charge population analysis, Fuzzy bond order analysis, and energy barriers of O<sub>2</sub> dissociation. CO oxidation was used as a probe reaction to study the reactivity of Cu-containing clusters, and it is found that the reactivity decreases with the increase of the size of silicon-oxygen clusters. Our results give a new aspect to understand the reaction mechanism of non-precious metal single-atom catalyst for oxygen activation with high efficiency.展开更多
Agrochemicals are indispensable materials in agricultural production,used to control or prevent diseases,insects and weeds,and play important roles in ensuring both food security and food safety.Meanwhile,the negative...Agrochemicals are indispensable materials in agricultural production,used to control or prevent diseases,insects and weeds,and play important roles in ensuring both food security and food safety.Meanwhile,the negative impacts of modern synthetic pesticides on humans and the environment could not be neglected.Thus,the production,registration,application and monitoring of pesticides should be strictly checked to ensure their commercial product quality and safety to human health as well as to the environment.This review summarizes the analytical chemistry involved in the quality control(QC)analysis for commercial formulation,residue analysis,dietary risk assessment and regulation prospects of pesticides.The main concepts and contents of pesticide analytical chemistry are comprehensively introduced and analyzed.In addition,the requirements and criteria of the relevant guidelines from various organizations are discussed.Finally,the research frontier areas and future trending for the invention of new generation of agrochemicals,registration/enforcement,market monitoring and risk management of pesticides are discussed.展开更多
文摘<img src="Edit_bdc7d851-e537-40df-990c-d678defa9648.png" alt="" />(M = Au, Ag, Cu;<span lang="EN-US" style="font-size:9pt;font-family:"color:black;"><i>n</i></span>= 1, 2, 3) clusters were used as a cluster model to study the activation of oxygen molecules on single-atom catalysts. Structures of <img src="Edit_bb84deb7-e24a-4777-a2f6-a1621ddd2afc.png" alt="" /> clusters were studied by density functional calculations with global optimization. For each <span style="font-family:"color:black;white-space:normal;"><i>n</i></span>, the most stable structures are quite similar for different metal types, and the oxygen molecule prefers to be adsorbed onto M atoms. It is found that the activation degree of oxygen is higher on clusters with non-noble metal Cu than that of Ag or Au containing clusters, by comparing the changes of O-O bond length and vibrational frequency, natural charge population analysis, Fuzzy bond order analysis, and energy barriers of O<sub>2</sub> dissociation. CO oxidation was used as a probe reaction to study the reactivity of Cu-containing clusters, and it is found that the reactivity decreases with the increase of the size of silicon-oxygen clusters. Our results give a new aspect to understand the reaction mechanism of non-precious metal single-atom catalyst for oxygen activation with high efficiency.
基金supported by Guangxi Key Research and Development Program,China(No:AB21196039)the National Natural Science Foundation of China(No:32172439)Key Research and Development Program of Hainan Province,China(No:ZDYF2022XDNY232).
文摘Agrochemicals are indispensable materials in agricultural production,used to control or prevent diseases,insects and weeds,and play important roles in ensuring both food security and food safety.Meanwhile,the negative impacts of modern synthetic pesticides on humans and the environment could not be neglected.Thus,the production,registration,application and monitoring of pesticides should be strictly checked to ensure their commercial product quality and safety to human health as well as to the environment.This review summarizes the analytical chemistry involved in the quality control(QC)analysis for commercial formulation,residue analysis,dietary risk assessment and regulation prospects of pesticides.The main concepts and contents of pesticide analytical chemistry are comprehensively introduced and analyzed.In addition,the requirements and criteria of the relevant guidelines from various organizations are discussed.Finally,the research frontier areas and future trending for the invention of new generation of agrochemicals,registration/enforcement,market monitoring and risk management of pesticides are discussed.
