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[Objective] The problems of excessive CO2 emission, the greenhouse effect, and energy shortage have been widely discussed among countries worldwide. Electrocatalytic CO2 reduction reaction (ECO2RR) can realize the conversion of CO2 into value-added chemical fuel under mild conditions and the storage of renewable electricity, which is an effective way to promote China's aim of carbon peak and carbon neutrality. To pursue higher catalytic activity and product selectivity, researchers are committed to developing highly efficient ECO2RR electrocatalysts. In this paper, we designed Mo2CO2 MXene-based single-atom catalysts (SACs) (TM@Mo2CO2-Ov, TM = Fe, Co, Ni) according to the needs of ECO2RR, focusing on their electronic structure, catalytic performance, as well as reaction mechanism through theoretical simulation of the electrocatalytic process. [Methods] In this work, the CIF file of the Mo2CO2 MXene structure downloaded from the crystal structure database was first imported into the Materials Studio software. Then, the (110) crystal plane was cleaved, and a vacuum layer of 15 A was created. Afterward, a 3 x 3 supercell treatment was applied to the system. Next, the VASP software was utilized to perform structure optimization. After the Mo2CO2 structure was optimized, a vacancy site for an oxygen atom on the surface was constructed. Subsequently, the Fe, Co, and Ni metal atoms were introduced into the respective vacancy sites to create the Fe@Mo2CO2-Ov, Co@Mo2CO2-Ov, and Ni@Mo2CO2-Ov catalyst models, respectively. Finally, the VASP software was employed to optimize the catalyst structures and the adsorption structures of the reaction intermediates. The performance evaluation of ECO2RR on different SACs was obtained by studying the reaction mechanism of the production of C products (CO, HCOOH, CH3OH, and CH4). The free energy of ECO2RR was calculated using the computational hydrogen electrode mode, wherein the energy of (H+ + e-) remained equivalent to that of 1/2H2 at normal pressure and temperature. [Results] The calculated results showed the following: 1) In the Mo2CO2-Ov framework, single Fe, Co, and Ni atoms replaced the Mo atom at the center of the O defect. After structural optimization, it was found that these three structures did not change significantly, and the bond lengths only changed slightly. 2) The CO2 molecule was stably adsorbed on Fe@Mo2CO2-Ov, Co@Mo2CO2-Ov, and Ni@Mo2CO2-Ov via chemisorption. The structures of CO2 were significantly bent after adsorption, and the calculated absolute values of the interaction exceeded four. The DOS analysis showed that the occupation of d orbitals of Ni, Co, and Fe led to the adsorption difference. The d orbitals of Co and Fe were hybridized with the ng and nM* orbitals of CO2, which promoted the adsorption and activation of CO2. 3) The ECO2RR free energy diagram and reaction path analysis showed that Co@Mo2CO2-Ov had higher ECO2RR activity and better CH4 selectivity and was a better electrocatalyst for the formation of C1 products from ECO2RR than Fe@Mo2CO2-Ov and Ni@Mo2CO2-Ov. [Conclusions] By integrating the geometrical analysis, DOS calculation, and free energy analysis, Co@Mo2CO2-Ov was established as the ideal ECO2RR catalyst. The work can achieve the expected goal of significantly enhancing the ECO2RR performance and improving students' scientific research literacy to explore micromechanisms and processes through the extension of the experimental process. [ABSTRACT FROM AUTHOR]

Southwest China is one of the three largest continuous karst clusters in the world; therefore, studies on karst rocky desertification in this area are very important. For more than 20 years' control, the decreasing area and risk of karst rocky desertification has contributed to the continuous ecological improvement. Nowadays, studies on rocky desertification mainly focus on the eight provinces in Southwest China, which have been designated as rocky desertification monitoring areas by the Chinese government. After the first phase of the comprehensive control project for karst rocky desertification in 2016, the expansion trend of rocky desertification in the southwest region was effectively curbed. Subsequent articles published tend to focus on analyzing the current situation, comprehensive management, or species adaptability of rocky desertification monitoring areas. However, the Qinba region in Shaanxi Province is located outside the monitoring area. In the process of studying the karst geological relics of the Zhenba Sanyuan Tiankeng Group, signs of rocky desertification have been found, but there still exists a research gap in the investigation and research on karst rocky desertification in this area which is one of the areas with the richest biodiversity in China, known as "ecological lung", "central water tower" and "biological gene bank". Unfortunately, this area is burdened with poverty, so the investigation and study of karst rocky desertification in the Qinba region of Shaanxi Province is of great significance to ensure green and high-quality development and ecological civilization construction. In this paper, by analyzing the current situation of karst rocky desertification in Southwest China, we summarized its harm to the ecological environment and social economy, clarify natural and human factors resulting in rocky desertification, and integrate the typical treatment experience in Southwest China. We also introduce three technical methods, including remote sensing interpretation, UAV remote sensing survey and analysis of carbonate dissolution rate, to provide a scientific basis for studies on karst rocky desertification in the Qinba region of Shaanxi Province. Study results show that the area of karst rocky desertification in the Qinba region covers 63.37 km², and the areas of severe, moderate and mild rocky desertification cover 17.97 km², 21.60 km² and 23.80 km², respectively. Based on the survey results, there are both regional differences and some similarities in distribution patterns in the areas of rocky desertification development. Specifically, the degree of rocky desertification in the limestone area is more severe than that in the dolomite area. It is also more severe in the area with developed water system than that in the arid and semi-arid area, and the more active the new structure is, the more severe the rocky desertification is. Compared to the Southwest China, the degree of karst rocky desertification in the Qinba region of Shaanxi Province is relatively light, with a smaller distribution area, mainly due to the less rainfall in the study area. The karst rocky desertification in Beiyang mountain of Zhen'an county is the most severe, with an area of 7.28 km². In the 1960s, a large-scale free-range of livestock severely damaged vegetation. The indiscriminate deforestation by humans further exacerbated the process of rocky desertification. The rocky desertification in Hailuogong village of Shanyang county is also severe, covering an area of 5.83 km², because the landform in this area is a typical peak-cluster depression, which is likely developed into rocky desertification. The contradiction between people and land needs to be solved urgently. In conclusion, more monitoring and research efforts are needed in Beiyang mountain and Hailuogong where the rocky desertification is severe. Firstly, we should clarify the causes of rocky desertification in the Qinba region and compare them with the causes in Southwest China to determine whether the rocky desertification is mainly resulted from natural factors or human factors. Secondly, we should know how to clarify the causes of karst rocky desertification in the Qinba region; for example, we can dynamically monitor the change of rock desertification by field verification, remote sensing interpretation, climate change analysis, etc. We can also calculate the contribution rate of each influence factor by geographical detector model. Thirdly, we should further study influence factors of karst dissolution rate. We can monitor physical and chemical properties of soil (soil moisture, carbon dioxide concentration, pH, organic matter content and porosity) in areas with moderate to severe rocky desertification, and analyze the relationship between dissolution rate and physical and chemical properties of soil in rocky desertification areas. Finally, in order to provide basic data for carbon neutrality research in Shaanxi, we should conduct studies on the carbon sink of rocky desertification areas in the Qinba region, with the methods such as dissolution test pieces and hydrochemical runoff. [ABSTRACT FROM AUTHOR]

Carbon capture, utilization, and storage (CCUS) technology is a vital technical path to realize the low-carbon transformation of the coal power industry as well as a key means to ensure the safe and stable operation of the future power system. However, the current development path of coupling coal power and CCUS technology is not clear, and there is room for the optimization of the corresponding policy mechanism. This paper quantitatively estimates the contribution of CCUS application in the coal power industry to China's low-carbon energy transition strategy, describes the future development path of coal power's CCUS industrialization from the spatio-temporal dimension, and further constructs a comprehensive supporting policy system framework. The results show that the development of coupling coal power and CCUS technology is technically and economically feasible, which can not only achieve deep decarbon-ization of the power system and bring significant output and employment dividends in the coal power industry, but also effectively control the average carbon price level of society. In terms of the temporal dimension, the development path of coal power's CCUS industrialization in the future should be divided into three stages: technology research, development, and demonstration (2021--2030), large-scale application (2030--2040), and commercial development (2040--2060). In terms of the spatial dimension, the technically and economically feasible regions for cluster development are the Ordos Basin, the Junggar Basin, the Bohai Bay Basin, etc. Constructing a comprehensive policy support system framework incorporating ' macro support, fiscal and tax finance, market mechanism, technology research, development, and demonstration, as well as management system' is conducive to realizing a large-scale CCUS application in the coal power industry. In the stage of technology research, development, and demonstration of coal power's CCUS application, more definitive incentive policies such as storage subsidies, compensation for power generation hours, and feed-in tariff subsidies should be implemented. When the project cost drops to a certain extent, there should be a gradual transition to market-based policy tools such as carbon trading and green electricity trading mechanisms, and green finance should also be promoted. Based on the relevant conclusions, some targeted policy suggestions are put forward to provide references for promoting the green and low-carbon transformation of China's coal power industry. [ABSTRACT FROM AUTHOR]

New urbanization plays an important role in China's regional economic growth and green transformation. In this stage of high-quality economic development, the effect of the government-led new urbanization policy on reducing pollution and carbon emissions needs to be verified. Based on the data of 180 prefecture-level cities in China from 2004 to 2020, this paper built a difference-indifferences model from the two dimensions of ' pollution' and ' carbon emission' to empirically test the effect of the reduction of pollution and carbon emissions in new urbanization and its influencing mechanisms. The results showed that: (J) The new urbanization construction had a significant effect of reducing pollution and carbon emissions, which was characterized by its annual increase. The conclusion was still robust after validity and robustness tests. © Based on the ' location-feature-scale' dimensional urban heterogeneity, the effect of the reduction of pollution and carbon emissions was more significant in the samples of eastern cities, non-resource-based cities, cities with high human capital, and larger cities. Quantile estimation results showed that this effect in the new urbanization construction was increasing marginally. © Mechanism analysis showed that the new urbanization construction could not only directly promote the reduction of pollution and carbon emissions, but also effectively promote this reduction by fostering the overall upgrading of industrial structure, service structure, and performance-based technological innovation. However, the impact of input-based technological innovation on this reduction was not obvious. This article offers new ideas for the next stage of regional pollution control in China. It is suggested that the government should promote the synergy between the new urbanization and the reduction of pollution and carbon emissions and release the dividends of the new urbanization in regional green development in a more effective way with the help of industrial structure upgrading and performance-based technological innovation. [ABSTRACT FROM AUTHOR]