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To achieve carbon peak targets, realize carbon neutrality vision, and tackle global climate change, China must improve the carbon emission performance at the city level. Based on the carbon emission performance of 191 prefecture-level cities in China from 1997 to 2017, this paper analyses the evolution characteristics of urban carbon emission performance from three aspects: the overall spatial and temporal evolution, the differences according to both region and city size, and the differences among clusters categorized by carbon emission performance at the city level. This paper also reveals the impact of the social and economic transition on China's carbon emission performance. The results show that: (1) The overall level of carbon emission performance of Chinese cities is low, and there is a downward trend during the study period. The differences in carbon emission performance among cities are convergent, but there is a wide gap between high and low values. (2) The carbon emission performance of cities in eastern coastal areas is higher than that in non-coastal areas cities. Large urban agglomerations and economically developed regions, such as provincial capitals, are the agglomeration areas of high urban carbon emission performance values. (3) The carbon emission performance level of cities with similar sizes will converge. At the same time, such changes will enhance the differences among carbon emission performances at the city level within the same region. (4) Cities that belong to high urban carbon emission performance clusters are mainly distributed in the eastern region. Such cities are classified into large cities, supercities, and megacities. Compared with low urban carbon emission performance clusters, cities in high urban carbon emission performance clusters show a higher proportion in the medium-high level and high level of carbon emission performance. Moreover, cities in high urban carbon emission performance clusters are more likely to improve theirurban carbon emission performance. (5) The economic agglomeration effect, industrial structure adjustment and carbon intensity reduction have a significant impact on improving urban carbon emission performance. Population agglomeration has an incremental effect, and the anticipated benefits of environmental regulation have yet to be fully realized. The impacts of different clusters and different regions are variable. Finally, this paper advances policy enlightenment according to its research findings. [ABSTRACT FROM AUTHOR]

Due to a rise in industrial pollutants in modern life, the climate and energy crisis have grown more widespread. One of the best ways to deal with dye degradation, hydrogen production, and carbon dioxide reduction issues is the photocatalytic technique. Among various methods, catalytic technology has demonstrated tremendous promise in recent years as a cheap, sustainable, and environmentally benign technology. The expeditious establishment of carbon-based metal nanoparticles as catalysts in the disciplines of materials and chemical engineering for catalytic applications triggered by visible light is largely attributed to their advancement. There have been many wonderful catalysts created, but there are still many obstacles to overcome, which include the cost of catalysts being reduced and their effectiveness being increased. Carbon-based materials exhibit a unique combination of characteristics that make them ideal catalysts for various reaction types. These characteristics include an exceptional electrical conductivity, well-defined structures at the nanoscale, inherent water repellency, and the ability to tailor surface properties for specific applications. This versatility allows them to be effective in diverse catalytic processes, encompassing organic transformations and photocatalysis. The emergence of carbon-based nanostructured materials, including fullerenes, carbon dots, carbon nanotubes, graphitic carbon nitride, and graphene, presents a promising alternative to conventional catalysts. This review focuses on the diverse functionalities of these materials within the realm of catalysis materials for degradation, hydrogen production, and carbon dioxide reduction. Additionally, it explores the potential for their commercialization, delving into the underlying mechanisms and key factors that influence their performance. It is anticipated that this review will spur more research to develop high-performance carbon-based materials for environmental applications. [ABSTRACT FROM AUTHOR]

The present article presents the results of tribological investigations performed on an off-the-shelf engine lubricant containing nanoadditives of multilayered graphene and C60 fullerene alternately. As anthropogenic CO2 is believed to be highly responsible for global climate change, its emission is regulated in many countries. CO2 emissions can be significantly decreased by improving the efficiency i.e. decreasing the losses in an engine. Hence reducing frictional losses was the ultimate scope of the investigations presented in this article. The experiments were carried out on an oscillating tribometer at the Department of Internal Combustion Engines at Széchenyi István University. The experiments showed that multilayered graphene in engine lubricant did not modify the friction coefficient inevitably (-1% to +4%). Fullerene nanoparticles, however, reduced the friction by 4-8%. The optimal fullerene doping quantity that resulted in the lowest friction showed to be at around 0.14 wt%. [ABSTRACT FROM AUTHOR]