Bifunctional nanocrystals with integrated plasmonic and catalytic activities hold great promise for analyzing chemical reactions by in situ surface‐enhanced Raman spectroscopy. This Minireview gives ...a brief introduction to the general strategies for designing such nanocrystals, followed by four typical examples, including their fabrication, characterization, and potential limitation. We then use the reduction of 4‐nitrothiophenol and oxidation of 4‐aminothiophenol as two model systems to demonstrate the capabilities of these bifunctional nanocrystals to monitor chemical reactions for the elucidation of reaction mechanisms and measurement of kinetics. We conclude with perspectives on further development of these bifunctional nanocrystals into a viable platform for investigating other types of catalytic reactions.
SERS them right: Bifunctional nanocrystals with integrated plasmonic and catalytic activities hold great promise for analyzing chemical reactions by in situ surface‐enhanced Raman spectroscopy (SERS). This Minireview gives a brief introduction to the general strategies for designing such nanocrystals and their use in the elucidation of reaction mechanisms and measurement of kinetics.
In order to meet the ambitious emission-reduction targets of the Paris Agreement, energy efficient transition of the building sector requires building retrofit methodologies as a critical part of a ...greenhouse-gas (GHG) emissions mitigation plan, since in 2050 a high proportion of the current global building stock will still be in use. This paper reviews current retrofit methodologies with a focus on the contrast between data-driven approaches that utilize measured building data, acquired through either 1) on-site sensor deployment or 2) from pre-aggregated national repositories of building data. Differentiating between 1) bottom-up approaches that can be divided into white-, grey- and black-box modelling, and 2) top-down approaches that utilize analytical methods of clustering and regression, this paper presents the state-of-the-art in current building retrofit methodologies; outlines their strengths and weaknesses; briefly highlights the challenges in their implementation and concludes by identifying a hybrid approach - of lean in-situ measurements supplemented by modelling for verification - as a potential strategy to develop and implement more robust retrofit methodologies for the building stock.
•A state-of-the art review on data-driven building modelling techniques is presented.•The models are classified into top-down and bottom-up approaches.•Comparative discussion on white-, grey- and black-box models is included.•An outlook on the latest building data collection technologies is also included.
Direct urea fuel cell (DUFC) is an attractive and inexpensive method for the simultaneous wastewater treatment (urine and urea-contaminated water) and electricity generation. Many efforts have been ...made to increase the catalytic activity of Ni-based DUFC anodic catalyst toward urea oxidation, which is considered to be the best non-precious catalyst in alkaline media so far. Alloying Ni with other metals and/or non-metals, and increasing its surface area demonstrated a power of up to 26.9 mW cm−2 at room temperature, which is comparable to that obtained in direct alcoholic fuel cells using high loading of precious catalyst. However, this is still viewed as low-performance. This review presents a comprehensive picture of the mechanism of urea oxidation on Ni-based catalysts, the poisoning effect of catalysts and its possible remedies, as well as the different approaches in preparing highly active catalysts. We also analyze the performance and associated issues of DUFC using newly applied strategies to increase its open-circuit voltage and power output via alternative oxidants and re-designed chemical conditions in the cell.
The ice phase in clouds is essential for precipitation formation over continents. The underlying processes for ice growth are still poorly understood, leading to large uncertainties in precipitation ...forecasts and climate simulations. One crucial aspect is the Wegener–Bergeron–Findeisen (WBF) process, which describes the growth of ice crystals at the expense of cloud droplets, leading to a partial or full glaciation of the cloud. In the CLOUDLAB project, we employ glaciogenic cloud seeding to initiate the ice phase in supercooled low-level clouds in Switzerland using uncrewed aerial vehicles with the goal of investigating the WBF process. An extensive setup of ground-based remote-sensing and balloon-borne in situ instrumentation allows us to observe the formation and subsequent growth of ice crystals in great detail. In this study, we compare the seeding signals observed in the field to those simulated using a numerical weather model in large-eddy mode (ICON-LEM). We first demonstrate the capability of the model to accurately simulate and reproduce the seeding experiments across different environmental conditions. Second, we investigate the WBF process in the model by comparing the simulated cloud droplet and ice crystal number concentration changes to in situ measurements. In the field experiments, simultaneous reductions in cloud droplet number concentrations with increased ice crystal number concentrations were observed, with periods showing a full depletion of cloud droplets. The model can reproduce the observed ice crystal number concentrations most of the time; however, it cannot reproduce the observed fast reductions in cloud droplet number concentrations. Our detailed analysis shows that the WBF process appears to be less efficient in the model than in the field. In the model, exaggerated ice crystal number concentrations are required to produce comparable changes in cloud droplet number concentrations, highlighting the inefficiency of the WBF process in the numerical weather model ICON.
Engineering heterogeneous composite electrodes consisting of multiple active components for meeting various electrochemical and structural demands have proven indispensable for significantly boosting ...the performance of lithium‐ion batteries (LIBs). Here, a novel design of ZnS/Sn heterostructures with rich phase boundaries concurrently encapsulated into hierarchical interconnected porous nitrogen‐doped carbon frameworks (ZnS/Sn@NPC) working as superior anode for LIBs, is showcased. These ZnS/Sn@NPC heterostructures with abundant heterointerfaces, a unique interconnected porous architecture, as well as a highly conductive N‐doped C matrix can provide plentiful Li+‐storage active sites, facilitate charge transfer, and reinforce the structural stability. Accordingly, the as‐fabricated ZnS/Sn@NPC anode for LIBs has achieved a high reversible capacity (769 mAh g−1, 150 cycles at 0.1 A g−1), high‐rate capability and long cycling stability (600 cycles, 645.3 mAh g−1 at 1 A g−1, 92.3% capacity retention). By integrating in situ/ex situ microscopic and spectroscopic characterizations with theoretical simulations, a multiscale and in‐depth fundamental understanding of underlying reaction mechanisms and origins of enhanced performance of ZnS/Sn@NPC is explicitly elucidated. Furthermore, a full cell assembled with prelithiated ZnS/Sn@NPC anode and LiFePO4 cathode displays superior rate and cycling performance. This work highlights the significance of chemical heterointerface engineering in rationally designing high‐performance electrodes for LIBs.
A viable anode material composing of new‐type ZnS/Sn heterostructures with rich phase boundaries concurrently encapsulated into hierarchical interconnected porous nitrogen‐doped carbon frameworks (ZnS/Sn@NPC) is developed for high‐performance lithium ion batteries. Its Li+‐storage mechanism and origins of the superior performance are explicitly elucidated by combining in situ TEM/XRD/Raman studies, a suite of ex situ microscopic and spectroscopic characterizations with theoretical simulations.
•In situ measurements of four cases of internal insulation in Denmark are studied.•Hygrothermal performance at wall-insulation interfaces and behind beams are studied.•Measurements are analyzed with ...simulations and damage models.•Long term performance depends on several parameters.•All cases of internal insulation should be individually analyzed.
In heritage buildings with solid masonry walls, where external insulation is not an option, insulating internally is an alternative way to improve indoor climate and reduce energy consumption and heat loss through external walls. This study presents results from hygrothermal measurements performed in four different buildings in Denmark where internal insulation has been installed. The buildings are all heritage buildings from 1877–1932 and of solid masonry walls. The insulated façades differ in orientation, surface treatments, location, and insulation system. The insulation materials used are phenolic foam and polyurethane (PUR) foam, with calcium silicate channels in a grid of 40 × 40 mm. Measurement results and hygrothermal assessments indicate that a vapour barrier does not contribute positively to the performance of the system and the more vapour open, the better performance on solid masonry. However, the performance is highly dependent on other parameters like insulation thickness and surface treatment, and above all: the external hygrothermal loads. Therefore, before the application of internal insulation, every case should be carefully assessed in order to find the most suitable solution with regards to both thermal and hygrothermal performance.
When designing ground heat exchangers used with ground source heat pump systems, a critical design property is the thermal conductivity of the ground. Thermal response tests are used to measure the ...site-specific thermal conductivity and are also used to measure the thermal resistance of a borehole heat exchanger as installed. Thermal response tests are commonly used today for design of multiple borehole ground heat exchangers, where knowledge of the ground thermal properties can help avoid undersizing of ground heat exchangers, leading to poor system performance, and oversizing of ground heat exchangers, leading to overly costly systems. This review covers the development of the mathematical and numerical analysis procedures, development of the hardware and test procedures, and validation of the results. We take a historical perspective, going as far back as Lord Kelvin’s treatment of transient heat conduction problems in the 1880s, further development of which allowed analysis of conductivity measurements from transient needle probes by the 1950s. We focus on development of test rigs and test procedures in the 1980s and 1990s and validation of the measurements. More recent developments are covered throughout the review.
The spatial scale mismatch between satellite and in situ-based measurements can be reduced by deploying multiple in situ sites within the coarse pixel. However, upscaling in situ measurements from ...the ground-support scale to the coarse pixel scale is still necessary due to their "point" measurement characteristics. The previous upscaling methods were generally developed merely for the in situ measurements. Nevertheless, the uncertainty of in situ measurements, such as measurement errors and spatial representativeness errors, was not dealt with. Consequently, the upscaling results inevitably suffer from errors, which will finally propagate into the pixel scale ground "truth." For the first time, this study presents an improved upscaling method with the consideration of the uncertainty of in situ measurements based on the error theory and measurement adjustment theory. The effectiveness of the corrected upscaling coefficients was evaluated by comparing the accuracy of the corrected upscaling results with those based on the upscaling coefficients without considering the uncertainty of in situ measurements. The results indicate that the accuracy of the upscaling results can be enhanced by 11.06% in the condition in which in situ measurements suffer from large uncertainty. However, if the uncertainty of in situ measurements is negligible, the corrected upscaling model is not necessary because it does not bring many benefits. Although the effectiveness of this method was only tested on a limited study area, it makes an important first step toward a higher precision pixel-scale ground "truth," especially when the uncertainty of in situ measurements is nonnegligible.
(Mg,Co,Ni,Cu,Zn)O, a high-entropy oxide, has recently been proposed as an anode material for lithium-ion batteries (LIBs). It exhibits excellent cyclic stability, which is attributed to the ...high-entropy stabilization effect, as reported in previous studies. The presence of Mg may also help stabilize the electrode by helping conserve its original lattice structure during charging and discharging. In this work, (Mg,Co,Ni,Cu,Zn)O oxides with various amounts of Mg were synthesized, namely, (Mg,Co,Ni,Cu,Zn)O, (Mg0.8,Co,Ni,Cu,Zn)O, and (Co,Ni,Cu,Zn)O. To explore the impact of Mg in LIBs, cyclic voltammetry and galvanostatic charge–discharge measurements were conducted. In addition, changes in morphology were observed using operando synchrotron transmission X-ray microscopy. Through the aforementioned analyses, the role of magnesium was investigated, which is expected to assist in the development of high-entropy oxide electrodes for LIBs.
•(Mg,Co,Ni,Cu,Zn)O oxides with various amounts of Mg were synthesized.•The changes in morphology were observed by operando transmission X-ray microscopy.•The results reveal that the Mg ions in the HEO can stabilize the structure.
PDF
