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Reduced dimensional lead halide perovskites (RDPs) have attracted great research interest in diverse optical and optoelectronic fields. However, their poor stability is one of the most challenging obstacles prohibiting them from practical applications. Here, we reveal that ultrastable laurionite-type Pb(OH)Br can spontaneously encapsulate the RDPs in their formation solution without introducing any additional chemicals, forming RDP@Pb(OH)Br core-shell microparticles. Interestingly, the number of the perovskite layers within the RDPs can be conveniently and precisely controlled by varying the amount of CsBr introduced into the reaction solution. A single RDP@Pb(OH)Br core-shell microparticle composed of RDP nanocrystals with different numbers of perovskite layers can be also prepared, showing different colors under different light excitations. More interestingly, barcoded RDP@Pb(OH)Br microparticles with different parts emitting different lights can also be prepared. The morphology of the emitting microstructures can be conveniently manipulated. The RDP@Pb(OH)Br microparticles demonstrate outstanding environmental, chemical, thermal, and optical stability, as well as strong resistance to anion exchange processes. This study not only deepens our understanding of the reaction processes in the extensively used saturation recrystallization method but also points out that it is highly possible to dramatically improve the performance of the optoelectronic devices through manipulating the spontaneous formation process of Pb(OH)Br.

The controllable design and precise modulation of the functional properties of materials based on theoretical calculations has always been the goal of materials researchers. Through the comparative analysis of theoretical calculations and experimental phenomena, physical properties, including optical properties, electrical conductivity, and dielectric properties, can be further comprehended. In this work, on the basis of the first-principles calculations of many inorganic compounds, we selected BaSnSi3O9 (BSSO) as the research focus and found that it contained two cationic sites with completely different electronic characteristics. Among them, the electron density of cations at the Ba site shows obvious localization characteristics, whereas the Sn site shows strong interaction with the surrounding environment. This distinct difference in electronic characteristics is very beneficial to the research and design of materials with functional properties. When functional ions are introduced into Ba sites, the relatively complete independence of these ions will be maintained. That is, if an ion with multiple stable valence states is introduced at the Ba site, it will exhibit the coexistence of multiple valence states. However, if an ion is introduced at the Sn site, this ion will lose its independence and exhibit strong interaction with the surrounding crystal field environment. The rare earth element europium (Eu) with two stable divalent and trivalent valence states in its normal state was chosen as a probe to verify the theoretical predictions in this work. According to the calculation results, when Eu occupied the Ba site, the spectrum simultaneously showed the luminescence of Eu3+ and Eu2+, and had a larger luminescence quenching concentration when the influence of defects was ignored. When Eu occupied the Sn lattice site, it only showed the luminescence of Eu3+, and had a lower luminescence quenching concentration due to the attractive effect that the surrounding O atoms had on the Eu electrons. Our research indicates that the experimental results are consistent with the theoretical predictions. This paper analyzes the important role of Eu optical probes in terms of investigating their physical mechanisms and optical properties in detail. It will provide valuable inspiration for theoretical calculations to guide the design of materials and the modulation of their functional properties.

Quantifying the carbon footprint (CF) of food-demand can aid in mitigating the effects of global climate change, especially in the context of urbanisation, which enriches urban diets with animal products. Urbanisation also attracts large numbers of people migrating from rural areas and even across provinces in China. Migrants gradually shift from the dietary patterns of their hometowns, toward those of their destinations, a process known as “dietary acculturation.” However, few studies have explored the dietary CF resulting from such migrations. Here, we compared the dietary patterns of rural vs. urban households in 31 Chinese provinces, and quantified the CF of dietary acculturation by overlaying interprovincial migrant populations with geographically varied dietary patterns. Our results show that the mean net dietary CF increased by 21 Mt CO2e yr−1 due to dietary acculturation. The increased intakes of aquatic products and beef jointly contributed 75% of this CF growth, while declined cereal intake offset ∼44%. The wealthy province of Guangdong, which has the largest immigrant population, accounts for ∼30% of growth in the dietary CF. Regression analyses revealed that the Engel coefficient had a strong marginal effect on the variations in CF attributable to dietary acculturation. Additionally, the dietary CF of migrant populations was positively correlated with the virtual environmental flows (e.g., carbon, water, and energy) that are embedded in regional commodity trades. This quantification of the CF of dietary acculturation provides novel insights that may be used to further quantify the carbon emissions of food demand.

As national efforts to reduce CO2 emissions towards achieving Intended Nationally Determined Contributions (INDCs), policymakers require regional information for specific sectors to reduce uncertainties within national mitigation target. To understand the implementation barriers of the residential building sector towards achieving INDC, this study proposes an analytical framework for supporting robust decision making at the subnational level, in which a multi-objective optimisation model under uncertainty (MOOU) is developed for establishing decarbonisation pathways of the residential building sector. The proposed model has three key features: (1) systematic and robust decision-making with multi-objective optimisation of economic goals in the presence of uncertainties; (2) synergistic mitigation policies with gradual ramping-up adoption; and (3) quantitative evaluation of the finance provision and implementation rates of mitigation policies. The proposed model is then applied to provide in-depth insights into implementation barriers of 13 types of mitigation policies towards achieving INDCs targets in nine provinces in China, with parallel urban and rural analyses. Results show that the CO2 emissions of residential buildings in Heilongjiang, Liaoning and Beijing will have peaked by 2030. In particular, the CO2 emissions from cooling energy consumption of total building stocks will continually increase. Furthermore, improvements of building thermal efficiency and energy mix dominate the mitigation potential in northern China, while the southern China largely depends on the improvement of the efficiency of home appliances. The differences in measures’ mitigation effectiveness cause that southern China provinces have higher risks for achieving the subnational INDCs targets compared to northern China.

The district heating system accounts for 40% energy consumption of the building sector in China and still has tremendous growth potential due to the urbanisation. However, few studies have conducted explicit quantification on the drivers and the sustainable development of the district heating energy consumption of the building sector (DHEB) in China, although previous aggregation analysis on whole building energy service could convey implications on the district heating systems. This study investigates the driving factors of the DHEB in China between 2004 and 2016 using a decomposition analysis that incorporates effects of energy mix, heat production technology structure, energy intensity, heating area, and population. The decoupling status between the DHEB and gross domestic product (GDP) in China is then analyzed based on the Tapio decoupling index, along with the contributions of each driving factor to the decoupling. The results show that the effects of district heating area and population dominate the increase in the DHEB, while the heating energy intensity is the strongest factor reducing the DHEB. In addition, the shares of coal and heating boilers positively contribute to the increase in 2004–2008, and have a negative effect in 2008–2016. The complete reverse trend is found in the shares of gas and combined heat and power (CHP) during the same period. These results are largely associated with the implementation of “coal to gas” and the “elimination of old boilers” pushed by the Chinese government. Furthermore, a weak decoupling effect is mainly found between China’s DHEB and GDP from 2004 to 2016. The heating energy intensity is the strongest factor promoting the decoupling, while the growth of the district heating area and population leads to a weak decoupling.

Unmanned Aerial Vehicles rapid delivery routing of the emergency rescue in the complex mountain region was studied as a multistage decision problem. Firstly, the problem is defined in graph theory and the solving framework is analyzed. Secondly, the dynamic programming model is developed due to its multistage characteristic. Thirdly, the tabu list for the dynamic programming model is introduced so that the optimal routing of UAVs can be computed through solving a minimum cost flow problem. Finally, the effectiveness of the dynamic programming model and algorithm is verified through an example.

Fabrication of ultrathin (e.g., ∼2 nm) CsPbBr3 nanowires is still challenging for existing methods, for the extremely fast crystal growth process of CsPbBr3. Here, we developed a self-assembled nanotemplate-confined growth concept to prepare ultrathin CsPbBr3 nanowires. During electrospinning using the N,N-dimethylformamide (DMF) solution composed of polymethyl methacrylate (PMMA), PbBr2, CsBr, and capping agents, PMMA chains would assemble into nanochannels acting as nanotemplates within the electrospun PMMA fibers. Owing to the very limited amount of precursors within the nanochannels, ultrathin CsPbBr3 nanowires were prepared after DMF evaporation. The CsPbBr3 nanowires within the PMMA fibers or dispersed in toluene showed bright blue luminescence. The structure of the CsPbBr3 products could be adjusted by the stirring time, as well as the amount of PMMA, PbBr2, and CsBr in DMF. Overall, we developed a new method towards engineering ultrafine CsPbBr3 nanostructure through self-assembled template-confined growth concept during electrospinning, which may find potential applications in blue light emitting diodes and other optoelectronic devices.

Contents lists available atScienceDirectSustainable Cities and Societyjournal homepage:www.elsevier.com/locate/scsLife Cycle Assessment of a solar thermal system in Spain, eco-designalternatives and derived climate change scenarios at Spanish and ChineseNational levelsJaume Albertía,¿,1, Juliana Raigosaa,b, Marco Raugeia,c, Rafael Assiegoa,d, Joan Ribas-Tura,e,Núria Garrido-Sorianof, Linghui Zhangg, Guobao Songg, Patxi Hernándezh, Pere Fullana-i-PalmeraaUNESCO Chair in Life Cycle and Climate Change ESCI-UPF, Universitat Pompeu Fabra, Pg. Pujades 1, 08003 Barcelona, SpainbInnovation Center on e-government, Ministry of Information and Communication Technologies, Bogotá, ColombiacFaculty of Technology, Design and Environment, Oxford Brookes University, Wheatley Campus, Oxford OX33 1HX, UKdETS Arquitectura, Energy Group-University of Malaga, Pl. El Ejido s/n, 29071 Málaga, SpaineESCI-UPF Research in International Studies and Economics (RISE), Universitat Pompeu Fabra, Passeig Pujades 1, Barcelona 08003, SpainfSustainability Measurement and Modeling Lab, Universitat Politècnica de Catalunya (UPC), School of Industrial, Aeroespace and Audiovisual Engineering of Terrassa,Colom st., 08222 Barcelona, SpaingKey Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology, Dalian University of Technology, No. 2Linggong Road, Ganjingzi District, Dalian 116024, PR ChinahTecnalia, Barrio Lasao, E-20730 Azpeitia, Gipuzkoa, SpainARTICLE INFOKeywords:Renewable energiesBuildingCircular economyNational emissionsNationally determined contributionsABSTRACTSolar thermal energy is considered a‘clean’form of energy; however, environmental impacts occur during itslife-cycle. The present work compares the environmental performance of two scenarios: a solar thermal systemfor providing domestic hot water (DHW) used in conjunction with a traditional natural gas heating system, andthe natural gas heating system on its own. Weak points are found and different eco-design scenarios are eval-uated in order to achieve a more circular economy. In addition, the authors explore what would be the nationalGreenhouse Gas emission reduction potential of a wider use of domestic solar hot water systems (DSHW) inChina’s and Spain’s built environment. In this case,five displacement methods are suggested to show how theemissions reduction vary.Through a review of the state of the art and a Life Cycle Assessment of a solar system the two scenarios areassessed. Some impact categories, such as global warming, suggest a markedly better performance of the solarsystem (-65%). However, weak points in the solar solution have been identified as there is an increase of impactsin cases such as acidification (+6%) and eutrophication (+61%), mostly due to the metals used. The compo-nents with higher environmental impact are the collector, the tank, and the copper tubes.The reduction of national emissions by promoting DSHW depends on the actual displaced technology/ies. Theconsequences on national emissions reduction depending on these choices are assessed. The potential reductionof emissions, if 30% of the DHW were covered with solar sources, would be between 0.38% and 0.50% in thecase of Spain and between 0.12% and 0.63% in China.