Search

Recently, microalgae had received extensive attention for carbon capture and utilization. But its overall efficiency still could not reach a satisfactory degree. Artificial photosynthesis showed better efficiency in the conversion of carbon dioxide. However, artificial photosynthesis could generally only produce C1-C3 organic matters at present. Some studies showed that heterotrophic microalgae can efficiently synthesize high value organic matters by using simple organic matter such as acetate. Therefore, the combination of artificial photosynthesis with heterotrophic microalgae culture showed great potential for efficient carbon capture and high-value organic matter production. This article systematically analyzed the characteristics and challenges of carbon dioxide conversion by microalgae and artificial photosynthesis. On this basis, the coupling mode and development trend of artificial photosynthesis combined with microalgae culture were discussed. In summary, the combination of artificial photosynthesis and microalgae culture has great potential in the field of carbon capture and utilization, and deserves further study., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Cities in China are on the frontline of low-carbon transition which requires monitoring city-level emissions with low-latency to support timely climate actions. Most existing CO 2 emission inventories lag reality by more than one year and only provide annual totals. To improve the timeliness and temporal resolution of city-level emission inventories, we present Carbon Monitor Cities-China (CMCC), a near-real-time dataset of daily CO 2 emissions from fossil fuel and cement production for 48 major high-emission cities in China. This dataset provides territory-based emission estimates from 2020-01-01 to 2021-12-31 for five sectors: power generation, residential (buildings and services), industry, ground transportation, and aviation. CMCC is developed based on an innovative framework that integrates bottom-up inventory construction and daily emission estimates from sectoral activities and models. Annual emissions show reasonable agreement with other datasets, and uncertainty ranges are estimated for each city and sector. CMCC provides valuable daily emission estimates that enable low-latency mitigation monitoring for cities in China., (© 2022. The Author(s).)

Abstract The fixation stage of cellular structure during polymer foaming process is difficult to control due to difficult removing of internal heat, especially for crystalline polymers such as polypropylene (PP). In order to control cellular structure in the fixation stage, we established an universal method by introducing water as an in-situ internal cooling agent during the foaming process of PP. Particularly, hydrophilic fillers were added into the high melt flow index polypropylene (HMI-PP) with poor foaming ability to study the effect of adsorbed water on the foaming process of PP/filler composites during sc-CO 2 batch foaming process. Compared to pure HMI-PP, HMI-PP/hydrophilic filler composites showed increased adsorption amount for water and melt viscosity. The water within the composites played a key role in the foaming process, which not only served as a physical foaming agent to increase the volume expansion ratio of PP composite foam, but also showed the function of rapid cooling foam proved by thermal imaging technology. As a result, the presence of some hydrophilic fillers within HMI-PP matrix significantly improved the foaming properties of HMI-PP, including preventing internal bubble collapse and significantly increasing the volume expansion ratio of the foam. The applicability of this method was validated using other PP materials besides HMI-PP, including high molecular weight PP (HMW-PP), high melt strength PP (HMS-PP). Graphical abstract Image Highlights • The presence of hydrophilic fillers enhanced adsorption amount of water in PP/filler composites. • Adsorbed water served as both in-situ cooling agent and foaming co-agent during CO 2 batch foaming process. • The in-situ cooling effect of adsorbed water in PP composites provides an efficient method to control cellular structure. [ABSTRACT FROM AUTHOR]

The Ni/Ce 0.8 Zr 0.2 O 2 catalysts with different Ni doping amounts (5 wt%, 10 wt%, 15 wt%, 20 wt%, and 25 wt%) are prepared by the impregnation technique and used as CO 2 methanation catalysts in this work. The effects of various Ni doping loading on CO 2 methanation catalytic performance at low temperatures were investigated in this catalytic system. The results show that the catalyst with 15 wt% Ni doping shows the best catalytic performance. Since the heated sintering of Ni nanoparticles was prevented efficiently by CO 2 methanation, these mesoporous catalysts exhibit excellent stability. Therefore, the catalyst is expected to be an efficient CO 2 methanation catalyst at low temperatures. [Display omitted] • Fabricating mesoporous Ce 0.8 Zr 0.2 O 2 solid solutions via one-pot EISA strategy. • Ce 0.8 Zr 0.2 O 2 supported Ni based catalysts by incipient impregnation method. • Ni species was greatly active and exhibits excellent co-chemical adsorption. • Ce Zr solid solution improved the redox property and thermal stability. [ABSTRACT FROM AUTHOR]

[Display omitted] • The ZSM-5 with short b-axis was synthesized by the hydrothermal method. • The Ni-based catalysts supported on ZSM-5 with different morphologies. • The influence of morphology on Ni-based CO 2 methanation catalyst was studied. • The La doped catalyst with short b-axis ZSM-5 support showed the optimum performance. • The reaction intermediates of CO 2 methanation studied by in-situ DRIFTS. A series of Ni-based catalysts supported on the ZSM-5 with different morphologies were facilely synthesized and employed as the CO 2 methanation catalysts. The achieved catalysts were systematically characterized by various techniques. Besides, the in-situ DRIFTS was also performed to investigate the intermediates of the CO 2 methanation reaction process. It was found that the catalyst with the short b-axis ZSM-5 support displayed much higher activity than other counterparts supported on nano ZSM-5 and commercial ZSM-5. The possible reason for this could be attributed to the unique morphology of short b-axis ZSM-5 zeolite with large external surface area (489.7 m2/g). In addition, it was also found the La doped catalyst displayed much higher low-temperature activity (200–300 °C) and CH 4 selectivity than the pristine counterpart without modification. Resultantly, the catalyst with both the short b-axis ZSM-5 support and La 2 O 3 modification displayed the optimum catalytic performance. Therefore, the morphology of the support and the selection of modifier were considered as the important concerns when designing and synthesizing Ni based CO 2 methanation catalysts with highly-developed performances. [ABSTRACT FROM AUTHOR]

High-performance, recycling and environmental protection are the goal of the development of polymer materials in the future. The introduction of crosslinking and composite are two main ways to improve the comprehensive properties of materials, however, which leads to the non-recyclability of materials or brings difficulties to the recovery process. Here, we report a polymer nanocomposite foam with superior compression properties to most existing commercial foams, just originating from common commercial styrene-acrylonitrile copolymer (SAN) and polyurea (PUA), and develop a green and energy-efficient method to fabricate high-performance rigid foam by reactive plasticizing and reaction induced phase-separation combining with supercritical CO 2 (sc-CO 2) foaming. Reaction induced phase-separation results in the in-situ formation of nanoscale structure in the cell walls of the resultant foams, in which the crosslinked PUA is the dispersed phase with the size of 10–40 nm in the matrix of SAN. Optimizing crosslinking network structure of PUA dramatically improve the comprehensive performance of SAN/PUA nanocomposite foams. The resultant SAN/PUA nanocomposite foam shows some performance characteristic of thermosetting polymers, such as excellent heat resistance and solvent resistance than the SAN matrix, meanwhile the performance characteristic of thermoplastic polymers, such as re-processability. More interestingly, the SAN/PUA nanocomposite foam presents excellent shape memory performance. With the above exceptional performances, this polymer nanocomposite foam will be a perfect substitute for the existing commercial rigid foams. [Display omitted] • SAN/polyurea nanocomposite foams show excellent comprehensive properties. • Forming nanostructure in the cell wall greatly improves the foam performances. • The prepared nanocomposite foam has outstanding anti-compressive performance. • Effect of crosslinking networks on the nanocomposite foam properties was clarified. [ABSTRACT FROM AUTHOR]

The influence of oleic acid modified Fe 3 O 4 (OA-Fe 3 O 4 ) nanoparticles on the morphology and foaming behavior of cocontinuous linear low density polyethylene/polystyrene (LLDPE/PS) immiscible blends (60/40 by weight) was studied. The morphology observation showed that the addition of nanofillers resulted in the increased dispersion degree of both LLDPE and PS components and even the transformation of phase structure from cocontinuous structure to sea-island structure, when enough amounts of nanoparticles were added. Meanwhile the introduction of enough amounts of OA-Fe 3 O 4 nanoparticles effectively enhanced the foaming ability of LLDPE/PS blend at semi-solid state during scCO 2 batch foaming. The mechanism analysis for the change of foaming behavior showed that the improved foaming capacity resulted from the change of the phase structure of LLDPE/PS blends and heterogeneous nucleation of OA-Fe 3 O 4 nanofillers. Sorption and desorption measurements showed that the addition of OA-Fe 3 O 4 nanoparticles in the LLDPE/PS blend increased the solubility of CO 2 , and the presence of enough amount of OA-Fe 3 O 4 decreased the desorption rate of CO 2 in the initial period of depressurization process, which are beneficial to cell nucleation and growth. Furthermore, it was found that the melt behavior and crystalline properties of LLDPE/PS blends were not the key factors to improved foaming behavior of the blends in the presence of OA-Fe 3 O 4 nanoparticles. [ABSTRACT FROM AUTHOR]

[Display omitted] • Amino-functionalized KCC-1 (AF-KCC-1) were synthesized by thermostatic reflux method. • The AF-KCC-1 was used as the support of Ni-based CO 2 methanation catalyst. • Regioselective precipitation of Ni2+ on amino group greatly promoted Ni dispersion. • Amino groups increased the medium surface alkalinity and abundant oxygen vacancies. • The 20Ni/AF-KCC-1 catalyst displayed superior low-temperature activity and stability. In this research, the highly dispersed Ni-based CO 2 methanation catalyst was facilely prepared by using the amino-functionalized KCC-1 (AF-KCC-1) as support. In this system, the surface-grafted amino functional groups over the KCC-1 support could evidently intensify the surface basicity. The regioselective precipitation of the Ni2+ would occur around the amino functional group during the catalyst preparation process by the incipient impregnation method. Subsequently, the metallic Ni active sites could be highly dispersed on KCC-1 support after the H 2 reduction. It was found that the 20Ni/AF-KCC-1 catalyst possessed better low-temperature activity and stability than the 20Ni/KCC-1 and 20Ni/SiO 2 reference catalysts without amino-functionalization. These catalysts were systematically characterized by various techniques. The results revealed that the amino-functionalized 20Ni/AF-KCC-1 catalyst displayed much smaller metallic Ni active sites than the reference catalysts. Furthermore, the in-situ DRIFTS and online TPSR were employed to study the potential reaction pathways of CO 2 methanation. The results demonstrated that the main reaction intermediates on the 20Ni/AF-KCC-1 catalyst greatly favored the formation of CH 4. The amino-functionalized AF-KCC-1 supported Ni-based catalyst exhibited much better anti-sintering performance than the reference catalysts during the 40 h stability tests at 400 °C. Therefore, the amino-functionalized KCC-1 was proposed as the promising support for preparing the highly dispersed Ni-based CO 2 methanation catalyst with a wide industrial application prospect. [ABSTRACT FROM AUTHOR]

In this study, we propose an innovative Hf 2 CO 2 /WS 2 heterostructure with excellent photocatalytic performance for water splitting based on first-principles calculations. The binding energy, and ab initio molecular dynamics (AIMD) simulations exhibit this material's excellent ambient stability. Furthermore, the band structure confirms that the Hf 2 CO 2 /WS 2 heterostructure possesses the intrinsic type-II semiconductor and are well satisfied with the requirements of redox energy level in water splitting reaction. Meanwhile, the charge transfer occurs from Hf 2 CO 2 to WS 2 monolayer, which further induces the separation of photogenerated carriers and prolong the lifetime of carriers. Dramatically high visible-light absorption (~6.3 × 105 cm−1) and carrier mobility (~2.2 × 103 cm2 V-1 s-1) are found, which means that the heterostructure has adequate motive force to make the photogenerated carriers separate into different monolayers quickly before recombination. Moreover, according to Gibbs free energy calculation, HER and OER can be triggered spontaneously under the driving of external potential. The results confirm that the thermodynamic feasibility of water splitting on Hf 2 CO 2 /WS 2 heterostructure surface. Hence, these distinctive features endow Hf 2 CO 2 /WS 2 heterostructure with the potential ability of photocatalytic water splitting, which provides a potential avenue for the future experimental project. [ABSTRACT FROM AUTHOR]

In this work, we explore the application potential of AsP/M 2 CO 2 (M = Sc, Zr) van der Waals heterostructures in photocatalytic water splitting through the first-principles calculations. The calculated results show that AsP/Zr 2 CO 2 heterostructure possesses an unfavorable type-Ⅰ band alignment, whereas AsP/Sc 2 CO 2 exhibits a desirable type-Ⅱ band alignment, which is beneficial for separating the photogenerated electron-hole pairs. Also, the band edge positions of AsP/Sc 2 CO 2 heterostructure stride the redox potential of water, ensuring favorable reaction kinetics. Besides, the strong optical absorption of AsP/Sc 2 CO 2 heterostructure in both visible and ultraviolet regions (especially up to 10−6 cm−1 at about 250 nm) makes it possible to utilize solar energy effectively. Meanwhile, AsP/Sc 2 CO 2 heterostructure has an exciton binding energy as low as 0.09 eV, which quantitatively illustrates the high separation efficiency of photogenerated charge carrier. Thus, the type-Ⅱ band alignment, suitable band edge position, strong light absorption, and low exciton binding energy together indicate that AsP/Sc 2 CO 2 heterostructure is a potential photocatalytic material. In addition, the obvious redshift phenomenon in the optical spectrum of AsP/Sc 2 CO 2 heterostructure shows that biaxial strain can improve its light capture capability. Also, the interconversion between type-Ⅱ and type-Ⅰ can be achieved by applying different strains. All these findings suggest that the novel AsP/Sc 2 CO 2 heterostructure has significant application prospects in next-generation photovoltaic and photocatalytic devices. • AsP/Sc 2 CO 2 heterostructure good optical absorption in visible and ultraviolet regions. • The lower exciton binding energy of AsP/Sc 2 CO 2 heterostructure confirms the effective carrier separation. • The conversion of heterostructure type and the improvement of optical properties are realized under biaxial strain. [ABSTRACT FROM AUTHOR]

• The law of the influence of pyrolysis atmosphere on the pyrolysis properties of plastics was investigated. • Explored the synergistic effect of mixed plastics. • The effect of atmosphere on the activation energy of plastic pyrolysis was explored. The Thermochemical method (pyrolysis) is the most promising means to treat waste plastics, which can be converted into high value-added products with significant economic and social benefits. In this study, the pyrolysis characteristics of single/mixed plastics under different atmospheres (nitrogen, carbon dioxide) were explored, and two kinetic models (KAS method and Friedman method) were used to calculate the kinetic parameters. The experimental results showed that carbon dioxide (CO 2) atmosphere can reduce the pyrolysis temperature of plastics. At the same time, the activation energy of single plastics under carbon dioxide (CO 2) atmosphere was lower than that of nitrogen atmosphere (N 2), with a decrease of about 7–60 kJ/mol, and the activation energy calculation results of mixed plastics were roughly similar. There was a positive synergistic effect between the mixed plastics under N 2 atmosphere, and the activation energy decreased from 234 kJ/mol to 221 kJ/mol, with a decrease of about 6%. There was a negative synergistic effect between the mixed plastics under CO 2 atmosphere, and the activation energy increased from 206 kJ/mol to 219 kJ/mol, with an increase of about 6%. The theoretical TG curve method also obtained similar conclusions. This experimental investigation can provide theoretical support for the environmentally friendly recycling technology of plastic waste. [ABSTRACT FROM AUTHOR]

[Display omitted] • The hollow ZSM-5 zeolites were synthesized by alkaline treatment of ZSM-5. • The Ni-based catalysts supported on ZSM-5 with different hollow structures. • The influence of hollow structure on Ni-based CO 2 methanation catalyst was studied. • The 15Ni/H-ZSM-5-T treated with TPAOH alkaline solution showed optimum performance. • The reaction intermediates of CO 2 methanation were studied by in-situ DRIFTS. Hollow ZSM-5 zeolites prepared using different alkaline solutions were employed as Ni based catalyst supports for the methanation of CO 2. The catalysts were thoroughly characterized, and in-situ DRIFTS were used to study the CO 2 methanation intermediates. Using the hollow Ni-based catalysts led to enhanced CO 2 conversion as well as CH 4 selectivity compared with the traditional Ni/ZSM-5, which was mainly due to the strong basicity of the hollow supports as well as the presence of silicon hydroxyls. Meanwhile, the 15Ni/H-ZSM-5-T catalyst prepared with TPAOH solution had higher catalytic performance than 15Ni/H-ZSM-5-NT and 15Ni/H-ZSM-5-N. The introduction of the hollow zeolite morphology led to enhanced diffusion behavior in the catalyst, which inhibited catalyst deactivation. Therefore, the hollow structure of the support with alkaline treatment was an important consideration for the design and preparation of high-performance Ni-based catalysts for CO 2 methanation. [ABSTRACT FROM AUTHOR]

[Display omitted] • ▶ The Ni-HMS catalyst was facilely synthesized by one-pot method at room temperature. • ▶ The Ni active sites were highly dispersed among the mesoporous HMS frameworks. • ▶ The in-situ DRIFTS and online TPSR of CO 2 methanation revealed reaction pathways. • ▶ The anchor effect of Ni active sites improved the anti-sintering performance. • ▶ The Ni-HMS performed higher CO 2 methanation activity than supported Ni catalysts. In this work, a series of hexagonal mesoporous silica (HMS) confined Ni-based CO 2 methanation catalysts were successfully synthesized by the facile one-pot strategy. In the Ni-HMS system, the metallic Ni active sites were embedded in the framework of HMS support. Hence, the metallic Ni active sites were highly dispersed and stably confined by the HMS framework. The kinetic study demonstrated that the Ni-HMS catalysts behaved much lower apparent activation energy than the 15Ni/HMS and 15Ni/SiO 2 catalysts, accounting for their enhanced low-temperature activities. Meanwhile, the online TPSR and in-situ DRIFTS of the CO 2 methanation were employed to study the reaction intermediates over these catalysts. The CHOO–, CH x O-, and CO x were considered as the reaction intermediates over the Ni-HMS catalysts and the possible reaction pathways were also proposed. In conclusion, the Ni-HMS catalysts were considered as a series of efficient and stable catalyst candidates for CO 2 methanation. [ABSTRACT FROM AUTHOR]

[Display omitted] • A series of rare earths (Pr, Sm, Ce and La) doped Ni/KCC-1 catalysts were prepared. • The addition of rare earth oxides regulated the Ni dispersion and basic sites. • The rare earths increased the metal-support interaction and oxygen vacancies. • The rare earths affected the reaction intermediates and apparent activation energy. • The Sm 2 O 3 doped catalysts performed the optimum low-temperature activity. In this work, a series of rare earths (Pr, Sm, Ce, La) doped Ni/KCC-1 catalysts were prepared and used for CO 2 methanation. It was found that doping the rare earths could greatly improve the low-temperature catalytic activities and promoting effect of Sm was more prominent than other doped counterparts (Pr, Ce, La). The effect of the Sm loading amount on the catalytic activity were further evaluated. The kinetic studies revealed that the rare earth doped catalysts performed lower apparent activation energies than the pristine Ni/KCC-1 catalyst. In order to reveal the behind reasons, these catalysts were comprehensively characterized via XRD, XPS, TEM, SEM-EDS, CO 2 -TPD, H 2 -TPR, etc. It was found that the presence of the rare earth dopants could evidently intensify the metal-support interaction, promote the dispersion of the metallic Ni active sites, generate abundant surface oxygen vacancies, and enhance the amount of the medium basic sites. Besides, the online TPSR and in-situ DRIFTS indicated that the addition of the rare earth oxides could affect the type of the reaction intermediates and the potential pathway of the CO 2 methanation. In general, these rare earths doped catalysts were deemed to be the superb catalyst candidates for the low-temperature CO 2 methanation. [ABSTRACT FROM AUTHOR]

[Display omitted] • The CeO 2 supports with varied morphologies were prepared by the hydrothermal method. • The morphology effect of these Ni/CeO 2 catalysts were investigated. • The 5Ni/NPs catalyst showed the most excellent low-temperature performance. • The apparent activation energies of the catalysts were studied by the kinetic study. • Online TPSR and in-situ DRIFTS of CO 2 methanation used to reveal reaction mechanism. A series of CeO 2 supports with particular morphologies (nanorods, nanocubes, nanooctas, and nanoparticles) were successfully fabricated by controlling the parameters of the hydrothermal method. The obtained nano-CeO 2 materials were utilized as the supports of the Ni-based CO 2 methanation catalysts prepared by the incipient impregnation method. It was found that the catalyst supported on the CeO 2 nanoparticles (5Ni/NPs) exhibited much higher catalytic activity and better stability than those of catalysts with other morphological CeO 2 supports. Thus, the catalytic performance of Ni/CeO 2 catalysts could be facilely tuned and optimized by precisely designing the morphology of the CeO 2 support. The XPS, CO 2 -TPD, and H 2 -TPR characterizing techniques showed that Ni-based catalysts supported on nano-CeO 2 with varied morphologies displayed different catalytic performances. It was supposed that the typical merits, such as the abundant oxygen vacancy, medium basic sites, moderate metal-support interaction, excellent reduction ability, etc. , were considered as the main origins for the enhancement of the low-temperature catalytic activities. Furthermore, the kinetic study revealed that the Ni-based catalysts supported on the nano-CeO 2 with varied morphologies performed the different apparent activation energies toward CO 2 methanation. The specific reaction intermediates and possible reaction pathways were carefully investigated through the in-situ DRIFTS and online TPSR techniques. Overall, this work would provide new perspectives that the roles of the morphology effect of the support ought to be emphatically considered when designing new catalysts. [ABSTRACT FROM AUTHOR]