Developing isolated single atomic noble metal catalysts is one of the most effective methods to maximize noble metal atom utilization efficiency and enhance catalytic performances.Layered double hydroxides(LDHs)are tw...Developing isolated single atomic noble metal catalysts is one of the most effective methods to maximize noble metal atom utilization efficiency and enhance catalytic performances.Layered double hydroxides(LDHs)are two-dimensional nanoarchitectures in which M^(3+) and M^(2+) sites are atomically isolated due to static repulsions,providing special anchoring sites for single noble metal atoms and enabling the tuning of catalytic activity.Herein,a comprehensive review of the advances in LDHs supported single-atom catalysts(M/LDH SACs)is presented,focusing on the synthetic strategies,structure characterization,and application of M/LDH SACs in energy devices.Strong electronic coupling between single atomic noble metal atoms and corresponding anchoring sites of LDHs determines not only the catalytic activity of M/LDH SACs but also the stability during catalytic reactions.Furthermore,a perspective is proposed to highlight the challenges and opportunities for understanding the reaction mechanism and development of highly efficient M/LDH SACs.展开更多
Drought is one of the main factors limiting the agricultural planting and production;gravel mulching is an effective inhibiting evaporation and water-saving planting pattern in the arid regions. In this study, experim...Drought is one of the main factors limiting the agricultural planting and production;gravel mulching is an effective inhibiting evaporation and water-saving planting pattern in the arid regions. In this study, experiments were conducted to study soil moisture effect and regression model with different gravel mulching, the soil moisture content and evaporation were compared that gravel mulched with different particle sizes, different thickness layer and different mulched years. The results showed that: 1) The cumulative soil evaporation of gravel mulched was only 29.3% of that bare fields. Mulching gravel could significantly reduce soil moisture evaporation. 2) The effects of inhibiting soil moisture evaporation are the best when mulch gravel thickness is 10 - 15 cm. 3) The particle size of gravel mulched is smaller, the evaporation inhibition effect will be better. Considering the water holding capacity and material economy, it is the most suitable to mulch gravel with the particle size of 3 - 5 cm. 4) Mulching gravel on the soil surface for 1 - 3 years can improve the soil moisture content. However, the gravel was mulched for more than five years, the soil moisture content decreased significantly. 5) The quadratic polynomial regression fitting model can better simulate and predict the cumulative evaporation on different gravel mulched, and the regression fitting degree R<sup>2</sup> is more than 0.98.展开更多
基金This work was supported by the National Natural Science Foundation of China,the National Key Research and Development Project(2021YFA1502200)the Royal Society and Newton Fund through a Newton Advanced Fellowship award(NAF\R1\191294)+3 种基金the Program for Changjiang Scholars and Innovation Research Team in the University(IRT1205)the Fundamental Research Funds for the Central Universities,the starting-up foundation from Beijing University of Chemical Tech-nology,the fellowship of China Postdoctoral Science Foundation(2020M670107)the Natural Science Foundation of Beijing,China(2214062)the China Scholarship Council and a long-term subsidy from China's Ministry of Finance and the Ministry of Education.
文摘Developing isolated single atomic noble metal catalysts is one of the most effective methods to maximize noble metal atom utilization efficiency and enhance catalytic performances.Layered double hydroxides(LDHs)are two-dimensional nanoarchitectures in which M^(3+) and M^(2+) sites are atomically isolated due to static repulsions,providing special anchoring sites for single noble metal atoms and enabling the tuning of catalytic activity.Herein,a comprehensive review of the advances in LDHs supported single-atom catalysts(M/LDH SACs)is presented,focusing on the synthetic strategies,structure characterization,and application of M/LDH SACs in energy devices.Strong electronic coupling between single atomic noble metal atoms and corresponding anchoring sites of LDHs determines not only the catalytic activity of M/LDH SACs but also the stability during catalytic reactions.Furthermore,a perspective is proposed to highlight the challenges and opportunities for understanding the reaction mechanism and development of highly efficient M/LDH SACs.
文摘Drought is one of the main factors limiting the agricultural planting and production;gravel mulching is an effective inhibiting evaporation and water-saving planting pattern in the arid regions. In this study, experiments were conducted to study soil moisture effect and regression model with different gravel mulching, the soil moisture content and evaporation were compared that gravel mulched with different particle sizes, different thickness layer and different mulched years. The results showed that: 1) The cumulative soil evaporation of gravel mulched was only 29.3% of that bare fields. Mulching gravel could significantly reduce soil moisture evaporation. 2) The effects of inhibiting soil moisture evaporation are the best when mulch gravel thickness is 10 - 15 cm. 3) The particle size of gravel mulched is smaller, the evaporation inhibition effect will be better. Considering the water holding capacity and material economy, it is the most suitable to mulch gravel with the particle size of 3 - 5 cm. 4) Mulching gravel on the soil surface for 1 - 3 years can improve the soil moisture content. However, the gravel was mulched for more than five years, the soil moisture content decreased significantly. 5) The quadratic polynomial regression fitting model can better simulate and predict the cumulative evaporation on different gravel mulched, and the regression fitting degree R<sup>2</sup> is more than 0.98.
