Sacrificial Template Research Articles

Non-PGM Cathode Electrocatalysts for PEM Fuel Cells

Polymer electrolyte membrane fuel cells, PEMFCs, are considered the most ideal next generation energy conversion device, able to provide power to a broad range of applications; automotive, combined heat and power, portable electronic devices. Pt-based electrocatalysts are regarded as ideal for promoting the desired redox reactions of a fuel cell, especially the sluggish oxygen reduction at the cathode, ORR. High expense and scarcity of Pt are the greatest impediments to successful commercialization of this technology. The replacement of unsustainable noble-metal catalysts with platinum group metal (PGM)-free catalysts for oxygen reduction reaction (ORR) is essential for material wise and market value viable PEMFCs.Among the different attempts towards non-PGM catalysts, incorporating atomically dispersed transition metal atoms (Fe, Mn, etc.) and heteroatoms (N, S, etc.) into carbon frameworks is the most promising [1,2]. Large specific surface area, high intrinsic ORR electrocatalytic activity, efficient porosity and sufficient stability in acid media and/or in the actual working environment are the least requirements to consider when designing the catalysts. So far, despite the tremendous efforts, many drawbacks still persist that include poor understanding of the nature of active centres and their control over the synthesis, as well as fast decay of the structure under operation.In this work, we will present a rationally designed strategy to prepare hybrid composite catalysts by developing Fe–N–C materials onto different 2D and 3D templates [3,4] with differentiated surface chemistry (silicon and heteroatom-doped carbon structures). Despite structural and physicochemical characterization, the study includes extensive electrochemical characterization in terms of activity and durability in relative to the application conditions. An example is depicted in Figure 1 for a single atom Fe-N-C catalyst synthesized using porous silica nanotubes as the sacrificial template resulting in a hierarchically porous structure with a surface area of 370 m2/g. Electrochemical study revealed a half-wave potential of 0.72 V and an onset potential of 0.88 V with high stability in acidic environment.Very importantly, the different findings are correlated to one another, thereby establishing a composition to function relationship to provide a pathway for the integrated engineering of novel structures with improved performance. Acknowledgments Funding from the Operational Program “Competitiveness, Entrepreneurship & Innovation” (EPAnEK), NSRF 2014-2020 through the project Solar2HyP Τ2ΕΔΚ-01877 References [1] L. Osmieri, et al., Current Opinion in Electrochemistry 25 (2020) 100627.[2] T. Asset, et al., Joule 4 (2019) 33-44.[3] Jin-Cheng Li et al., Asia Materials 10 (2018) e461[4] Nan Zhang et al., Energy Environ. Sci. 13 (2020) 111-118 Figure 1

Salting-out/sacrificial template strategy for the preparation of hydrogels as efficient solar evaporators

Hydrogels have recently emerged as promising solar evaporators due to their exceptional high evaporation rates. However, the high costs and complexity associated with the conventional freezing-thawing processes pose challenges that hinder their widespread application in large-scale solar evaporation systems. Herein, we present the successful attempt to prepare hydrogel-based solar evaporators using a salting-out/sacrificial template strategy, where salt particles serve as both salting-out agents and sacrificial templates. Without the need for freezing processes, we successfully synthesized polyvinyl alcohol (PVA) hydrogels, incorporating copper oxide and antimony-doped tin oxide particles as solar absorbers. It is demonstrated that the salting-out (Hofmeister) effect enables the cross-linking of PVA polymeric chains, imparting significant mechanical strength and durability to the hydrogels. Meanwhile, the use of salt particles as sacrificial templates creates well-developed microchannels of 100–300 μm within the hydrogels, enabling rapid water delivery. These hydrogels exhibited a solar-weighted absorptivity of 93.4 % and achieved solar evaporation rates exceeding 3.0 kg m-2h−1 under one-sun illumination. Notably, their performance is comparable to that of state-of-the-art hydrogels prepared using freezing-thawing methods. As such, this proposed strategy holds great promise for the large-scale and cost-effective production of hydrogels as high-performance solar evaporators.

Manufacturing multifunctional vascularized composites by through-thickness frontal polymerization and depolymerization: A numerical study on the impact of sacrificial fiber configurations

Concurrent through-thickness frontal polymerization and vascularization (FP-VaSC) is emerging as a promising alternative to conventional multi-step fabrication approaches for vascularized thermoset polymers and composites. This method relies on a localized and self-propagating exothermic polymerization reaction front of the polymer matrix, to simultaneously cure the matrix, and depolymerize pre-embedded sacrificial templates. It delivers fully cured thermoset polymers and composites rapidly and energy-efficiently with the desired vascular system in a single step. While previous studies demonstrated the capability of this method for making woven laminates with a single vascular channel created by embedding a single straight sacrificial fiber, it is desirable to explore the potential of this method for making composites with multiple channels for more practical applications. We employ a previously validated thermo-chemical model from our prior study, to systematically investigate the reaction process with the presence of multiple sacrificial fibers. Two sacrificial fiber configurations are considered, namely, inline and staggered fiber configurations. Within each configuration, we consider a range of horizontal and vertical fiber spacing, which also lead to different sacrificial fiber volume fractions. This study reveals the interactions between the sacrificial fiber and the reactions, identifies the working window of this method for different sacrificial fiber configurations, and provides guidance for manufacturing laminates with multiple vascular channels. We also propose an analytical model that can quickly approximate the maximum sacrificial fiber volume fraction that can lead to successful FP-VaSC for a given carbon fiber volume fraction and compare the results with those from the thermo-chemical modeling.

Fabrication and Characterization of Zein/PDADMAC Nanoparticles to Encapsulate Tebuconazole by Antisolvent Precipitation Method**

AbstractIn order to improve the sustained release effect and antifungal activity of tebuconazole (TEB), zein /poly dimethyl diallyl ammonium chloride (PDADMAC) nanoparticles (NPs) were prepared in this study. The hollow zein NPs were made by anti‐solvent precipitation method in which sodium carbonate was chosen as sacrificial template, and PDADMAC was combined with zein NPs via electrostatic self‐assembly after loading TEB. The NPs were characterized through particle size, Zeta potential, scanning electron microscopy (SEM), sustained release effect, contact angle, encapsulation efficiency (EE), loading efficiency (LE) and antifungal activity. In this study, TEB/zein/PDADMAC NPs were stable for at least 28 days at room temperature. The release of TEB showed lower release in NPs compared with technical concentrate (TEB TC, 98 %). In addition, NPs also significantly influenced performance such as wetting performance and antifungal activity. The developed functional TEB/zein/PDADMAC NPs with excellent properties can be promising for antifungal pesticide applications.

Direct ink writing of hierarchical porous SiC ceramics as catalyst support for hydrogen production

Due to the tunable porosity at multiple scales, hierarchical porous ceramics feature large specific surface area and excellent heat and mass transfer performance, which can effectively improve the catalytic reaction performance. This paper presents a method to fabricate SiC scaffolds with regular and hierarchical pore structures by direct ink writing (DIW) combined with sacrificial template technology, which can be used as methanol steam reforming (MSR) microreactor catalyst supports. Through printing along a defined path, primary pores with a regular pore structure were created. After sintering, the sacrificial template was removed and secondary pores appeared. Four different types of hierarchical porous SiC scaffolds were successfully prepared and the pore structure, total porosity, linear shrinkage and compressive strength of these scaffolds were investigated. The catalyst coating was then loaded onto the scaffold, and the microstructure characterization showed that the pore structure would not be damaged and blocked. Finally, the hydrogen production experiments were carried out on the MSR microreactor, and the results showed that the support with larger and denser secondary pores had the best fluid flow and hydrogen production characteristics. At the temperature of 280 °C and the gas hourly space velocity (GHSV) of 30000 ml g−1 h−1, the methanol conversion and hydrogen production of the best support can reach 90.95 % and 44.96 ml/min, respectively.

Porosity effect on the functional properties and energy harvesting performance of Ba0.85Ca0.15Ti0.90Zr0.10O3 ceramics

AbstractIn this study, the effect of porosity on the structural and functional (dielectric, ferroelectric, nonlinear, and piezoelectric) properties in Ba0.85Ca0.15Ti0.90Zr0.10O3 ceramics was investigated. Various levels of microporosity in the range of 3% to 31 vol.% have been produced using poly(methyl methacrylate) microspheres as sacrificial templates. The structural investigation indicates a phase coexistence, as expected for this composition at room temperature. The maximum permittivity decreases with increasing porosity, from around 7000 (ceramic with 3 vol.% porosity) down to 3500 (ceramic with 31 vol.% porosity), and the Curie temperature shifts from 47 to 67°C when increasing porosity, related to the possible porosity‐induced structural and internal stress modifications. An enhanced piezoelectric response was found in the Ba0.85Ca0.15Ti0.90Zr0.10O3 ceramic with intermediate porosity around 18 vol.%, with the highest value of piezoelectric response of 470 pC/N and a figure of merit of 7.3 pm2/N. The optimum piezoelectric properties at the intermediate porosity level are related to the microstructural changes (pore shape and connectivity) and possible field‐induced structural modifications. The piezoelectric energy harvesting measurement results have shown the possibility of using Pb‐free porous ferroelectric materials in devices for energy harvesting applications.

Development of topology-optimized structural cavities macro-encapsulating chloride salt by gel-casting for high-temperature thermal energy storage

The thermal energy storage (TES) technology based on high-temperature molten salt is playing an increasingly important role in advanced solar energy utilization and waste heat recovery. However, the high corrosivity and low thermal conductivity of molten salt have limited the efficient application of TES systems. This work reports a facile and novel sacrificial paraffin template method, aiming to create Al2O3 ceramic macrocapsules with topology-optimized structural cavities by paraffin blocks with a reverse-designed structure for macro-encapsulating molten salt. The objective function of the maximum thermal conductivity of the design domain is calculated by a topology-optimized method to optimize the layout of high conductive ceramics. Among them, the optimized macrocapsules with a volume ratio of 25 % ceramic (S25) have a 62.8 % reduction in charging time and a 101.5 % increase in charging rate. Furthermore, after being filled with eutectic chloride salt, S25 could present a satisfactory heat storage density of 272.58 J∙g−1 and 748.3 J∙cm−3 at the temperature range of 550–750 °C. The macrocapsules also show good thermal cycling stability without degradation of thermophysical properties after hundred cycles. These improved results demonstrate the potential application of the macrocapsule in high-temperature TES systems.

Core-Shell ZIF-8@ZIF-67-Derived Cobalt Nanoparticle-Embedded Nanocage Electrocatalyst with Excellent Oxygen Reduction Performance for Zn-Air Batteries.

Metal-nitrogen-carbon (M-N-C) catalysts obtained from zeolitic imidazolate frameworks (ZIFs) have great potential in the oxygen reduction reaction (ORR). Herein, based on the same three-dimensional (3D) topological structure of ZIF-67 and ZIF-8, ZIF-67 is grown on the ZIF-8 surface by the epitaxial growth method, and ZIF-8 is used as a sacrificial template to obtain a Co-embedded layered porous carbon nanocage (CoPCN) electrocatalyst. Meanwhile, the self-sacrificing template effectively improves the specific surface area of the porous structure and reduces the depletion of active sites. The CoPCN shows a high half-wave potential of 0.885 V and superior stability as well as excellent methanol resistance. Theoretical calculations demonstrate that the Co-N1-C2 sites of CoPCN effectively reduce the energy barrier of ORR. In addition, a zinc-air battery (ZAB) based on the CoPCN exhibits excellent peak power density (90 mW cm-2) and superior cycle performance. This work presents a novel idea in the design of ZIF precursor systems to synthesize efficient ORR catalysts.

Au Octahedral Nanosponges: 3D Plasmonic Nanolenses for Near-Field Focusing.

Here, we report the synthesis of three-dimensional plasmonic nanolenses for strong near-field focusing. The nanolens exhibits a distinctive structural arrangement composed of nanoporous sponge-like networks within their interior. We denote these novel nanoparticles as "Au octahedral nanosponges" (Au Oh NSs). Employing a carefully planned multistep synthetic approach with Au octahedra serving as sacrificial templates, we successfully synthesized Au Oh NSs in solution. The porous domains resembling sponges contributed to enhanced scattering and absorption of incident light within metal ligaments. This optical energy was subsequently transferred to the nanospheres at the vertex, where near-field focusing was maximized. We named this observed enhancement a "lightning-sphere effect". Using single particle-by-particle surface-enhanced Raman scattering (SERS), we optimized the morphological dimensions of the spheres and porous domains to achieve the most effective near-field focusing. In the context of bulk SERS measurements targeting weakly adsorbing analytes (2-chloroethyl phenyl sulfide) in the gas phase, we achieved a low detection limit of 10 ppb. For nonadsorbing species (dimethyl methyl phosphonate), utilization of hybrid SERS substrates consisting of Au Oh NSs and metal-organic frameworks as gas-adsorbing intermediate layers was highly effective for successful SERS detection.

A synergetic poring strategy to prepare high porosity SiC ceramic foam with good mechanical strength

AbstractMicrostructure‐tailored high porosity silicon carbide (SiC) ceramic foams were successfully fabricated using polymeric precursor slurry through a synergetic pore‐forming strategy that combines direct foaming and sacrificial template method together. The slurry is composed of a vinyl‐containing liquid polycarbosilane, poly(methyl methacrylate) (PMMA) microspheres, and composite inorganic fillers. The expandable PMMA served a dual role as both foaming agent and sacrificial template, while the liquid polycarbosilane was used as both binder and preceramic polymer. The green bodies foamed from precursor slurry were pyrolyzed at 1150, 1400, and 1600°C, respectively, to produce corresponding SiC ceramic foams. The pyrolysis behavior of the green body foams and the crystallization behavior of the SiC ceramic foams were studied. Notably, the SiC ceramic foam derived from the slurry containing 65 wt% filler exhibited low density (0.26 g/cm3), high porosity (90.3%), high compressive strength (3.87 MPa), and low thermal conductivity (0.34 W/mK). The SiC ceramic foams displayed attractive oxidation resistance, and the foams with a porosity of 90.3% can retain 75.2% of their initial compressive strength after oxidation for 10 h at 1400°C.

Digital light 3D printed fast- and controlled degradation of covalent hydrogel networks

Digital light processing (DLP)-based 3D printing of hydrogels with sophisticated structures has been widely used in myriads of fields. However, the inherent covalently crosslinked network of hydrogels limits their further applications, such as working as sacrificial molds. In this work, a photocurable hydrogel system with labile covalent bonds suitable for DLP based printing to fabricate 3D complex hydrogel structures with fast- and controlled degradation ability is reported. The hydrogel precursor is composed of polyethylene glycol 400 (PEG400), a water soluble photoinitiator, and PEGDA575-Do, a degradable photocurable diacrylate monomer that can be degraded in aqueous condition via reversable aza-Michael addition reaction. The mechanical properties of formed hydrogels can be regulated by changing the PEG content and water content, and the degradation rate can be regulated by changing parameters such as PEG400 content, water content and the treating temperature. Moreover, the DLP printed degradable hydrogels networks can be used as sacrificial molds to fabricate structures from materials that cannot be directly used for DLP 3D printing (e.g. thermoplastic polycaprolactone (PCL), epoxy-based resin, and chocolate). As proofs-of-concept, a microfluidic chip is fabricated by using the biocompatible 3D printed hydrogel as a sacrificial template. Similarly, a flexible RFID tag and a flexible self-powered device are also prepared, demonstrating the potential applications in the field of flexible electronics.

Attaining high energy density using metal-organic framework-derived NiO/Co3O4/NiCo2O4 as an electrode in asymmetric hybrid supercapacitor

This study investigates the potential of hybrid NiO/NiCo2O4/Co3O4 composite as electrode for high-performance supercapacitors. Hydrothermally synthesized Ni(BDC) and Co(BDC) as sacrificial templates with different mass ratios are used to obtain NiO/NiCo2O4/Co3O4 nanocomposite. Notably, the electrochemical studies revealed that NiO/NiCo2O4/Co3O4 derived from a 4:1 mass ratio of Ni-MOF and Co-MOF displayed the highest specific capacity value of 1108.9C g−1 at 2 A g−1 with enhanced rate capability and excellent electrochemical stability, with 95.3 % retention up to 5000 cycles at 10 A g−1. The enhancement of specific capacity is attributed to the multiple metal oxidation states (Ni2+, Ni3+, Co2+, Co3+), surface oxygen defects, and the reduced solvation effect due to mesoporous structure and higher specific surface area. The assembled hybrid asymmetric supercapacitor (NiO/NiCo2O4/Co3O4 //Carbon Black) demonstrated a remarkable specific capacity of 416.95C g−1 at 0.5 Ag−1 with 89.1 % retention up to 5000 cycles at 10 A g−1 and an exceedingly high energy density of 89.81 W h kg−1 at a power density of 387.49 W kg−1. Even at a high-power density value of 7740 W kg−1, the device maintained an impressive energy density of 72.43 W h kg−1.

Room temperature solid electrolyte ozone sensor based on Ag-doped SnO2

In this paper, SnO2 was synthesized using MOFs as a sacrificial template, and Ag-doped SnO2 composite was synthesized by reducing AgNO3 with NaBH4, and O3 sensors were prepared using sodium superionic conductor (NASICON) as a solid electrolyte. At room temperature, the gas-sensitive experimental tests showed that the response of the sensor with 3 wt% Ag-SnO2 to 180–420 ppb O3 increased by about 57% and the sensitivity increased by 9.9% compared to the pure SnO2 sensor. The repeatability and stability of the 3 wt% Ag-SnO2 sensor were tested at 240 ppb O3, and the results showed that the repeatability of the sensor varied between − 2% and 2%, and the stability varied between − 4% and 4%. Therefore, the solid electrolyte sensor prepared by the excellent Ag-doped SnO2 composite material has a good application prospect in the detection of low-concentration O3.

Flexible Sensors with a Multilayer Interlaced Tunnel Architecture for Distinguishing Different Strains.

The diversity of body joints and the complexity of joint motions cause flexible strain sensors to undergo complex strains such as stretching, compression, bending, and extrusion, which results in sensors that do not recognize different strains, facing great challenges in detecting the true motion characteristics of joints. Here, the monitoring of body joints' real motion characteristics has been realized by the sensor that can output response signals with different resistance trends for different strains. The sensor prepared by the sacrificial template method is characterized by a multilayered interlaced tunnel architecture and carbon black embedded in the inner wall of the tunnel. Stretching, compressive, and bending strains result in increasing, decreasing, and increasing resistance, followed by a decrease in resistance of the sensor, respectively. The sensor can still output distinguishable response signals, even in the presence of complex strains induced by squeezing. Low strain detection limits (0.03%) and wide detection ranges (>600%) are achieved due to the localized strain enhancement caused by the unique structure. The sensor can detect the motion characteristics of different joints in flexion-extension, abduction-adduction, and internal-external rotation, which, in turn, can be used for real-time monitoring of complex joint motions involved in limb rehabilitation. In addition, the sensor recognizes the 26 letters of the alphabet represented by sign language gestures. The above studies demonstrate the potential application of our prepared sensors in flexible, wearable devices.

Performance and mechanism of efficient activation of peroxymonosulfate by Co-Mn-ZIF derived layered double hydroxide for the degradation of enrofloxacin

Due to the uncontrolled synthesis of layered double hydroxides (LDHs), a simple and efficient strategy was needed to construct high-performance LDHs. Herein, Co-Mn-ZIF was used as the sacrificial template to form cobalt-manganese-nickel LDH (M−Co−Mn−Ni LDH) through the process of deconstruction and reconstruction. Due to the sufficient in-situ etching of the Co-Mn-ZIF template, M−Co−Mn−Ni LDH exhibited a larger specific surface area (482.4 m2/g) and pore volume (3.3 × 10−2 cm3/g) as well as easier diffusion and interaction with reaction sites of organic molecules. The prepared M−Co−Mn−Ni LDH showed high catalytic performance for the degradation of enrofloxacin (ENR) by activating peroxymonosulfate (PMS), with the removal rate of 88.5 % within 30 min. The quenching reaction and electron paramagnetic resonance (EPR) analysis results indicated that SO4•− and 1O2 were main active substances in the oxidation process of ENR. In addition, the Co-Mn-Ni LDH/PMS system was stable and almost unaffected by pH values, organic and inorganic substances, and it could achieve high removal efficiency in various pollutant samples. This work provided a convenient and efficient approach for the construction of high-performance MOFs derived LDHs catalysts.

Electrochemically inducing V2O5·nH2O nanoarrays vertically growth on VSx microrods for highly stable zinc ion battery cathode

The lack of suitable cathode materials greatly limits the potential applications of rechargeable aqueous zinc ion batteries (ZIBs), despite their great promise in terms of high safety, high energy density, and low cost. One promising cathode material is VOOH, which possesses high specific capacity and fast Zn2+ transport channels after a phase transition to V2O5·nH2O during electrochemical cycling. However, its susceptibility to structural disintegration and aggregation during charging and discharging leads to severe capacity decay. To address this issue, we construct a composite consisting of VOOH particles and VSx microrods by a one-step hydrothermal method using a vanadium-based metal-organic framework (MIL-88B(V)) as a sacrificial template. The VOOH particles undergo electrochemical activation and transform into V2O5·nH2O nanoarrays that vertically grow on the VSx microrods. This unique nano-composite effectively maintains the morphology of nanoarrays in electrochemical cycling, resulting in a significant enhancement of rate performance and long-term cycling stability. Moreover, the VSx itself provides considerable capacity and its high conductivity improves the rate performance of the composite. Consequently, the VOOH/VSx nanocomposite exhibits a superior capacity of 364 mA h g−1 at 0.2 A g−1 after activation. Notably, it maintains remarkable capacity retention of 99.6% after 700 cycles, even at a high current density of 10 A g−1. Based on these findings, we believe that the VOOH/VSx composite holds great promise as a cathode material for aqueous ZIBs.

MIL-100(V) derived porous vanadium oxide/carbon microspheres with oxygen defects and intercalated water molecules as high-performance cathode for aqueous zinc ion battery

The development of aqueous zinc ion battery cathode materials with high capacity and high magnification is still a challenge. Herein, porous vanadium oxide/carbon (p-VOx@C, mainly VO2 with a small amount of V2O3) core/shell microspheres with oxygen vacancies are facilely fabricated by using a vanadium-based metal–organic framework (MIL-100(V)) as a sacrificial template. This unique structure can improve the conductivity of the VOx, accelerate electrolyte diffusion, and suppress structural collapse during circulation. Subsequently, H2O molecules are introduced into the interlayer of VOx through a highly efficient in-situ electrochemical activation process, facilitating the intercalation and diffusion of zinc ions. After the activation, an optimal sample exhibits a high specific capacity of 464.3 mA h g−1 at 0.2 A g−1 and 395.2 mA h g−1 at 10 A g−1, indicating excellent rate performance. Moreover, the optimal sample maintains a capacity retention of about 89.3% after 2500 cycles at 10 A g−1. Density functional theory calculation demonstrates that the presence of oxygen vacancies and intercalated water molecules can significantly reduce the diffusion barrier for zinc ions. In addition, it is proved that the storage of zinc ions in the cathode is achieved by reversible intercalation/extraction during the charge and discharge process through various ex-situ analysis technologies. This work demonstrates that the p-VOx@C has great potential for applications in aqueous ZIBs after electrochemical activation.

Facile synthesis of antimony-embedded nitrogen-rich carbon composites using sacrificial template: Enhanced stability for high-performance sodium-ion hybrid capacitors

Sodium-ion hybrid capacitors (SIHCs) offer a cost-efficient, high-energy, high-power solution for next-generation energy storage. The primary challenge is the development of suitable active materials. Ideal anodes should possess high capacity, low operating voltage, excellent rate performance, and cycling stability. In particular, alloy-based materials have the potential to serve as efficient anodes if their volume changes during cycling can be suppressed. In this work, we developed a facile and simple approach for the synthesis of alloy-based Sb nanoparticles embedded in a nitrogen-enriched carbon matrix (denoted as Sb@NC) through a straightforward chelation process. By incorporating NaCl as a sacrificial template, we successfully reduced the overall size of the carbon matrix, further mitigating volume change during charge–discharge process, and formed pores in the composite that facilitate the transport of sodium ions (denoted as s-Sb@NC). The material exhibited a high capacity (544.4 mAh g−1@0.1 A g−1), superior rate performance (238.9 mAh g−1@5 A g−1), and robust stability, with the capacity of 224.2 mAh g−1 after 1000 cycles. Through in-situ analyses, we determined the charge–discharge mechanism, and ex-situ cross-sectional imaging revealed the causes behind the decreased performance of commercial Sb and Sb@NC with the progress of the charge–discharge cycle. SIHC device was assembled with our developed materials and activated carbon and it exhibited outstanding energy/power density and cycle stability compared with recently reported results. SHIC delivered a maximum energy and power density of 192.6 Wh kg−1 and 18.6 kW kg−1, and showed a capacity fade of only 0.0028 % per cycle over 20,000 cycles at a high current density of 5 A g−1.

Fabrication of Yttrium Oxide Hollow Films for Efficient Passive Radiative Cooling

In recent years, many parts of the world have researched the transition to renewable energy, reducing energy consumption and moving away from fossil fuels. Among the studies to reduce energy consumption, passive radiative cooling can reduce the energy used for building cooling, and to improve this, the optical properties of atmospheric window emissivity and solar reflectance must be increased. In this study, hollow yttrium oxide (H-Y2O3) was fabricated using melamine formaldehyde (MF) as a sacrificial template to improve the optical properties of passive radiative cooling. We then used finite-difference time-domain (FDTD) simulations to predict the optical properties of the fabricated particles. This study compares the properties of MF@Y(OH)CO3 and H-Y2O3 particles derived from the same process. H-Y2O3 was found to have a solar reflectance of 70.73% and an atmospheric window emissivity of 86.24%, and the field tests revealed that the temperature of MF@Y(OH)CO3 was relatively low during the daytime. At night, the temperature of the H-Y2O3 film was found to be 2.6 °C lower than the ambient temperature of 28.8 °C. The optical properties and actual cooling capabilities of the particles at each stage of manufacturing the hollow particles were confirmed and the cooling capabilities were quantified.

Synthesis, characterization, and application of the novel nanomagnet adsorbent for the removal of Cr(vi) ions

Abstract The synthesis of an efficient adsorbent to remove chromium ions from water is challenging. Therefore, in this study, a new nanomagnet composite (Fe3O4/biochar/ZIF-8) was synthesized by a one-pot hydrothermal method using a metal–organic framework (MOF, ZIF-8) as a sacrificial template, citrus peels as a source of biochar, and iron oxide nanoparticles for magnetization. The synthesized nanocomposite showed a high efficiency toward the adsorption of Cr(vi) ions. The adsorption study showed that the experimental data were well-described using the Langmuir isotherm model and pseudo-second-order model. According to the Langmuir model, the adsorption capacities toward Cr(vi) adsorption were 77 and 125 mg·g−1 for Fe3O4/biochar and Fe3O4/biochar/ZIF-8, respectively, indicating the role of MOF in improving the adsorption performance. The Fe3O4/biochar/ZIF-8 showed an excellent adsorption performance in the presence of coexisting ions at a wide pH range using different eluents to study reusability up to five successive cycles. We can conclude from this study that this nanoadsorbent is a promising material for removing pollutants from environmental water samples.