High Humidity Conditions Research Articles

Structured Cerium-Manganese Catalysts Supported on Nickel Foam for Toluene Oxidation by Electric Internal Heating.

Structured catalysts are widely used in catalytic oxidation of gaseous pollutants, hot catalysis is usually needed to assist the reaction in the catalytic process. Herein, a Ce-modified manganese oxide octahedral molecular sieves (Ce-OMS-2) structured catalyst supported on foam nickel was prepared through impregnation process. A systematically quantitative testing on the toluene catalytic oxidation effectiveness of this structured catalyst was conducted through catalyst evaluation device, combining a series of characterization methods, such as XRD and SEM, the structure-activity relationship was established. Assisted with electric internal heating and ozone oxidation environments, this structured catalyst exhibits excellent catalytic oxidation performance for oxidative decomposition of toluene even under high humidity conditions. The results showed that the ozone-coupled structured nickel foam catalyst increased the decomposition efficiency of toluene from 25 % (without catalyst and heating) to 55 % (with catalyst and without heating) and the electric internal heating can significantly improve the reactivity and moisture resistance of the structured nickel-foam catalyst, at 90 % RH and 40000 h-1, 50000 ppb O3 and 40 mg/m3 toluene was maintained 100 % catalytic efficiency. The high-efficiency non-precious metal-based electrothermal catalyst prepared herein is expected to have certain enlightenment for the purification of VOCs.

Phenotypic evaluation of USDA peanut (Arachis hypogaea L.) mini-core collection for resistance against stem rot caused by Sclerotium rolfsii Sacc.

Sclerotium rolfsii is a necrotrophic fungus that causes devastating stem rot disease on peanuts under high temperature and humidity conditions. Developing more resistant stem rot varieties is a better disease management strategy from an economic and environmental point of view. In this study, 105 peanut accessions from the USDA mini-core collection were screened for resistance against stem rot under growth chamber and greenhouse conditions at the New Mexico State University Agricultural Science Center in Clovis, NM, USA. The accessions were inoculated with a virulent isolate of S. rolfsii, and disease development was monitored and scored at 5, 7, 9, 11, and 17-days post-inoculation (DPI). Mean disease score, lesion length and broad sense heritability were calculated, and cluster analysis was performed. Though the accessions were not significantly different for the mean disease parameters, numerical differences were observed in disease score and lesion length among the accessions at 17-DPI. Eleven accessions showed moderate resistance and performed better than stem rot resistant commercial cultivar, ‘G03L’, and ninety-four accessions were susceptible based on mean disease scores under both growing conditions. Low broad-sense heritability for disease score (0.05 to 0.06) and lesion length (0.03 to 0.06) under different environments indicates that most of the variance for these traits is due to environmental effects, and that stem rot resistance can be a complex trait. The identified resistant accessions can be used for genotyping and finding major QTLs through genome-wide association mapping to dissect genetic basis of stem rot resistance in peanuts. This information would be helpful to the peanut breeding program to develop more resistant varieties.

Evaluation of Lipidomics Profile of Quinoa Flour and Changes during Storage Based on Ultra Performance Liquid Chromatography Coupled with Quadrupole Exactive Orbitrap Mass Spectrometry.

Although quinoa is nutritious, its high fat content and lipase activity make it easily oxidized during storage. Meanwhile, quinoa's lipid composition and changes during storage are still unknown. Therefore, we stored fresh quinoa flour at low temperature and low humidity (LL), normal temperature and normal humidity (NN), and high temperature and high humidity (HH) conditions for 120 days to assess its oxidative stability and to monitor the changes in lipid composition. Herein, the contents of fatty acids, the peroxide values, the malondialdehyde values, and the lipase activity in quinoa flour during storage are determined to evaluate its oxidation stability. At LL and NN conditions, the contents of fatty acids, the peroxide values, the malondialdehyde values, and the lipase activity changed slowly. They were 3 (LL) and 5 times (NN), 2.7 (LL) and 4.7 times (NN), 1.4 (LL) and 2.3 times (NN), and 1.5 (LL) and 1.6 times (NN) the initial content at storage up to 120 d. However, with the prolongation of storage time under HH conditions, they all increased significantly to 8, 6.6, 3, and 2 times the original content. Moreover, during the storage of quinoa under LL, NN, and HH conditions for 120 days, we continuously monitored the lipid composition of quinoa grains with UPLC-Q-Exactive Orbitrap MS/MS. We identified a total of 14 subclasses of 229 lipids, including 90 significantly different lipid species. PCA and PLS-DA showed that quinoa lipids in HH conditions changed significantly with prolonged storage; among these, the TG and DG classes were the most susceptible to oxidation, which could distinguish fresh quinoa from oxidized quinoa. Simultaneously, we also found that lipase activity has a significant impact on lipid metabolism through correlation analysis, which also indicates that enzyme inactivation treatment can slow down lipid hydrolysis and oxidation during storage. To explore the mechanism of these changes, we also identified twelve important lipid metabolism pathways during quinoa storage. In conclusion, our study advances knowledge of the storage stability and lipid oxidation mechanisms of quinoa and provides a theoretical basis for setting the shelf life of quinoa.

Effect of Hydrophilic Layer in Double Microporous Layer Coated Gas Diffusion Layer on Performance of a Polymer Electrolyte Fuel Cell

Abstract Water flooding under high current and humidity conditions is a main barrier to enhancing the performance of polymer electrolyte fuel cells (PEFCs). This study evaluated a double microporous layer (MPL) coated gas diffusion layer (GDL) consisting of a thin hydrophilic layer coated on a hydrophobic MPL coated GDL. An accurate measurement of the contact angle was introduced to assess the wettability of the MPL. In addition, the water breakthrough pressure and water vapor permeance values were measured to evaluate the water transport ability of the MPL. The oxygen transport resistance was measured using the limiting current density in polarization curves. Appropriate hydrophilic MPL containing 5% Nafion, 25% TiO2, and carbon black in the double MPL enhanced the ability of the GDL to discharge water at the catalyst layer, effectively reducing water flooding. The total oxygen transport resistance obtained with the double MPL was reduced by about 20% compared to that obtained with a hydrophobic MPL. Moreover, the pressure-independent and pressure-dependent resistances were separated from the total oxygen transport resistance measured under various back pressure conditions. The double MPL exhibited a substantially reduced pressure-independent resistance at the interface between the MPL and the catalyst layer.

Analysis of hygroscopicity and pyrolysis behaviour of propanediol esters synthesized by the enzymatic method

AbstractIn order to develop food or tobacco usable flavour precursors, compounds 2‐hydroxypropyl benzoate (3a), propane‐1,2‐diyl dibenzoate (4a), 2‐hydroxypropyl cinnamate (3b) and propane‐1,2‐diyl (2E,2′ E)‐bis(3‐hydroxypropyl cinnamate) (4b) were synthesized by transesterification propanediol with vinyl benzoate and vinyl cinnamate under the biological enzyme Novozym435. The structures of the propanediol esters were characterized using nuclear magnetic resonance (1H NMR, 13C NMR), infrared spectroscopy (IR) and high‐resolution mass spectrometry (HRMS). The hygroscopicity and moisture retention capacity of reconstituted tobacco shreds with the synthesized propanediol were explored by 100 h hygroscopic desorption assay, model validation and low‐field nuclear magnetic resonance imaging (LF‐NMR). The results showed that the bound water content of 3a and 3b was lower than that of propanediol and higher than that of the control under both low (RH = 32%) and high (RH = 84%) humidity conditions. In addition, pyrolysis‐gas chromatography/mass spectrometry (Py‐GC/MS) technique was applied to investigate the thermal behaviour of 3a and 3b. Four and five pyrolysis products were formed by pyrolysis of 3a and 3b, respectively. The main pyrolysis products benzoic acid and cinnamic acid could be used as flavouring agents in food and tobacco. 3a and 3b had good moisture and humidity retention effects as well as uniform and sustained flavour release. The results of the study not only effectively improve the water absorbency of reconstituted tobacco and enhance the flavour, which is suitable for the storage and smoking process, but also provide a reference for the further development of new flavour moisturizers in the tobacco industry.

High-humidity hot-air impingement blanching conditions for the inhibition of potato-browning enzymes and for quality retention.

Potato is an important non-cereal crop. It provides carbohydrates, a major source of energy in the human diet. Blanching during the processing of fresh fruits and vegetables is essential for their preservation. High-humidity hot-air impingement blanching (HHAIB) is a promising emerging technology for pretreating different food materials. This research aimed to identify the optimum HHAIB conditions for the inhibition of potato-browning enzymes, maintaining their nutritional and physical quality, and to compare this with conventional hot-water blanching (HWB). Polyphenol oxidase (PPO) inactivation, total phenol content (TPC), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, color, textural attributes, thermal properties, microstructure, and particles crystallinity were evaluated. The relative humidity (RH), temperature, and duration of HHAIB required for PPO inactivation (2.59%) were 50%, 105 °C, and 4 min, respectively, which resulted in a complete gelatigination of potato starches, based on the thermal properties and the microstrcture of the blanched potatoes. These conditions led to improvements in TPC to 312.54 μg GAE.g-1 FP, DPPH scavenging to 1.99 μmol TE.g-1 FP, as well as enhancements in color and crystallinity. When HHAIB was conducted at lower temperatures (85 and 95 °C) there were negative effects on the blanched potatoes' color and crystallinity, along with a non-safe level of PPO activity. High-humidity hot-air impingement blanching was superior to HWB, inhibiting PPO, maintaining nutrients, and preserving physical properties, especially under the optimum conditions revealed by the principal component analysis. It provides an excellent technique for blanching and pretreating potatoes, preserving them, and maintaining their quality. © 2023 Society of Chemical Industry.

A Flexible Self-Powered Noncontact Sensor with an Ultrawide Sensing Range for Human-Machine Interactions in Harsh Environments.

Noncontact human-machine interactions (HMIs) provide a hygienic and intelligent approach to communicate between humans and machines. However, current noncontact HMIs are generally hampered by the interaction distance, and they lack the adaptability to environmental interference such as high humidity conditions. Here, we explore a self-powered electret-based noncontact sensor (ENS) with moisture-resisting ability and ultrawide sensing range exceeding 2.5 m. A megascopic air-bubble structure is designed to enhance charge-storage stability and charge-recovery ability of the ENS based on the heterocharge-synergy effect in electrets. Besides, multilayer electret films are introduced to strengthen the electric field by utilizing the electrostatic field superposition effect. Thanks to the above improved performances of the ENS, we demonstrate various noncontact HMI applications in harsh environments, including noncontact appliances, a moving trajectory and accidental fall tracking system, and a real-time machine learning-assisted gesture recognition system with accuracy as high as 99.21%. This research expands the way for noncontact sensor design and may further broaden applications in noncontact HMIs.

Effect of High Temperature and Humidity on Bond Strength of Al/Resin Adhesive Joints

The adhesive strength and degradation behavior of the Al/resin interface was investigated under high temperature and high humidity conditions. The adhesive strength of the joint without aging was approximately 14 MPa. The value is the same as the Cu/resin joint. With progress of aging at 85°C in 85%R. H., the strength decreased rapidly in the early aging stage and decreased gradually by further aging. The strength of the Al/resin joint was inferior to that of the Cu/resin joint after aging. The fracture mainly occurred in the interface of the joint. The result of Fourier transform infrared spectroscopy analysis for the fracture surface showed that water absorption in the Al/resin joint occurs by aging and causes the degradation of the strength.

Efficient Photothermal Anti-/Deicing Enabled by 3D Cu2-x S Encapsulated Phase Change Materials Mixed Superhydrophobic Coatings.

Photothermal superhydrophobic surfaces are one of the most promising anti-/deicing materials, yet they are limited by the low energy density and intermittent nature of solar energy. Here, a coupling solution based on microencapsulated phase change materials (MPCMs) that integrates photothermal effect and phase change thermal storage is proposed. Dual-shell octahedral MPCMs with Cu2 O as the first layer and 3D Cu2-x S as the second layer for the first time is designed. By morphology and phase manipulation of the Cu2-x S shell, the local surface plasmonic heating modulation of MPCMs is realized, and the MPCM reveals full-spectrum high absorption with a photothermal conversion efficiency up to 96.1%. The phase change temperature and enthalpy remain in good consistency after 200 cycles. Multifunctional photothermal phase-change superhydrophobic composite coatings are fabricated by combining the hydrolyzed and polycondensation products of octadecyl trichlorosilane and the dual-shell MPCM. The multifunctional coatings exhibit excellent anti-/deicing performance under low temperature and high humidity conditions. This work not only provides a new approach for the design of high-performance MPCMs but also opens up an avenue for the anti-icing application of photothermal phase-change superhydrophobic composite coatings.

Allied species with Dicksonia sellowiana Hook. in a High Montane Araucaria Forest Remnant, in Southern Brazil

The Araucaria Forest in highlands is an environment characteristic of regions with altitudes greater than 1200 above sea level, in southern Brazil. The species that occur in this place are adapted to conditions of low temperatures and high humidity, where the presence of Dicksonia sellowiana Hook., a tree-sized pteridophyte with expressive importance value in many remnants. This research aimed to identify the associations of this species in a remnant of Araucaria Forest in the mountain region of Santa Catarina. The site was inventoried with permanent plots of fixed area of 200 m², which were systematically and contiguously distributed in 3 transects following the slope gradient of the terrain (1411 to 1940 m). The surveys evaluated the scientific name, geographic coordinates and DBH, with an inclusion limit of 5 cm for each individual. Subsequently, 14 individuals of D. sellowiana were randomly selected and used as a reference to the center of the sampling units of Prodan method, than the six closest trees were measured, identified and measured the distance from the center of the unit sampling to the sixth tree (R6) to determine its area. As the measurements of the permanent plots contain the geographic coordinates of all trees, the selection of Prodan sampling units and the collection of data (R6, N.ha-1, G.ha-1) were performed using ArcGis Software. The average basal area value was 69.5 m².ha-1 and the average density was 1628 ind.ha-1, values compatible with those obtained in the permanent plots (69.4 m².ha-1 and 1630 ind.ha-1 respectively), obtaining sample sufficiency by the collector curve. Dicksonia sellowiana showed association with 14 species, being inserted in characteristic environments with less sun exposure, slopes and presence of watercourses, generating an environment with low floristic diversity, however, with a high degree of endemism in the Atlantic Forest.

Water-durability and high-performance all-fiber humidity sensor using methyldiethanolamine-photopolymer-PDMS structure

In the context of optical fiber humidity sensing, the long-term stability of sensors in high humidity and dew environments such as bathrooms or marine climates remains a challenge, especially since many humidity sensitive materials are water soluble. In this study, we use methyldiethanolamine, pentaerythritol triacrylate and Eosin Y to form a liquid-solid structure humidity sensitive component, the outermost layer is coated with PDMS passivating layer to ensure the stability and durability of the humidity sensor under the conditions of dew and high humidity. The liquid microcavity of the sensor consists of methyldiethanolamine-pentaerythritol triacrylate composite solution, and the sensitivity is several times higher than that of the liquid-free cavity sensor. The sensitivity of the sensor to temperature is verified (0.43 nm/°C and 0.30 nm/°C, respectively) and temperature crosstalk is compensated using a matrix. The compact structure allows for ultra-fast response (602 ms) and recovery time (349 ms). Our work provides a promising platform for efficient and practical humidity and other gas monitoring systems.

Comparison of hermetic and conventional bags for maize seed preservation in Azad Kashmir, Pakistan

Maize (Zea mays L.) is a major cereal crop used as a staple food worldwide for decades. Farmers store their produce in porous polypropylene bags under humid conditions which negatively affects their quality. In this study, maize seeds were stored in hermetic and conventional bags with an initial seed moisture content of 13.5% (wet basis) and 96.3% germination for 8 months at four major maize growing districts (Athmuqam, Hattian Bala, Muzaffarabad and Rawlakot) of Azad Jammu and Kashmir, Pakistan. Due to high ambient relative humidity conditions (>80%), an increase in moisture was observed in seeds stored in porous conventional bags (14. 7%). This increase was because of high initial relative humidity conditions (79–85%) in conventional bags. Seed moisture content remained unchanged in hermetic bags and internal humidity was 59–60%. As a result of hermetic conditions, germination and seed integrity were maintained in hermetic bags compared to conventional woven bags. Germination drastically decreased in conventional bags and fell to 9 % (Athmuqam), 13 % (Hattian Bala), 11 % (Muzaffarabad) and 12 % (Rawlakot). Higher physical quality losses of maize in conventional bags were because of infestation activity of live insect pest populations (S. zeamais, R. dominica and T. castaneum) that initiated 21.7–23.7 % weight loss in polypropylene bags. Hermetic bags protected seeds from insect pest attack and maintained seed quality. Higher contamination of aflatoxin B1, G1, B2 and G2 (ppb) was recorded in seeds stored in conventional bags as compared to hermetic bags. Aflatoxin B1 was maximum in conventional bag at Hattian Bala (8.93 ppb) followed by Muzaffarabad (6.68 ppb), Athmuqam (5.02 ppb) and Rawlakot (0.71 ppb). In conclusion, the use of hermetic dry chain storage preserves maize seed quality and thus can have a significant impact on the livelihoods of smallholder farmers of humid areas.

Observational insights into the environmental effect for secondary inorganic aerosol formation in the Northeast China: Influence of biomass burning

Secondary inorganic aerosols (SIA), as one of the main ubiquitous components of PM2.5, still have unclear impacts on their formation in the ambient environment, especially under extremely cold weather conditions. To explore the effects of open biomass burning (OBB) source emissions and meteorological factors on SIA formation, biomass burning tracer, i.e., levoglucosan (LG), was observed along with SIA were analyzed during the heating season at the Longfengshan (LFS) background of Northeast China. Based on the LG/OC ratio and fire hotspots, the entire sampling campaign was divided into OBB and non-open biomass burning (NBB) periods.It was found that OBB emissions had little effect on sulfate formation but a significant impact on nitrate formation. High relative humidity (RH) conditions played a crucial role in SIA formation, with both SO42−/EC and NO3−/EC increasing as RH elevated at temperatures below −10 °C. Furthermore, the temperature dependence of SO42−/EC and NO3−/EC indicated that temperature could enhance the activity of either aqueous-phase production or gas-phase reactions, subsequently promoting the formation of SO42− and NO3− in the ambient environment. Additionally, positive matrix factorization (PMF) analysis was used to scientifically separate the sources of ambient aerosols during OBB and NBB periods.

Thermal Comfort Comparison and Cause Analysis of Low-Temperature High-Humidity Indoor Environments of Rural Houses in Gansu Province, China

Low temperatures and high humidity often occur in the northern basins and mountainous regions of China. This research reveals a common winter indoor environment in this rural areas characterized by low-temperature and high-humidity indoor thermal conditions. Improving this environment directly with equipment would inevitably result in significant energy consumption. Therefore, comprehending the thermal performance mechanisms of different structural building materials is of vital importance as it provides crucial baseline values for environmental improvement. This study conducted a survey utilizing user questionnaires, resulting in the collection of 214 valid responses. Additionally, a local experiment regarding thermal comfort was conducted. Simultaneously, this study monitored the indoor physical environments of these houses (a sample of 10 rooms was taken from earth houses and 12 rooms from brick houses). Parameters measured on site included air temperature, relative humidity, light illumination, and CO2. The results showed that the humidity inside the earth houses is more stable and regression models can be developed between thermal sensations and temperature for long-term residents. The residents of these earth houses are more sensitive to temperature step. In contrast, the residents of brick houses, experiencing greater environmental variability, demonstrated lower sensitivity and greater adaptability to temperature changes. In addition, heating from bottom to top is more comfortable and healthier for the residents of brick houses in Gansu. Moreover, it is more favorable for the inhabitants’ livelihood to regulate the temperature steps to a maximum of 4 °C. This study provides valuable reference information for the future design of houses in low-temperature and high-humidity environments.

Dual positive charging sites for MIL-101 enhanced adsorption of toluene under high humidity conditions: Experimental and theoretical studies

Highly efficient capture of volatile organic compounds (VOCs) under humid conditions is a significant yet formidable task for metal–organic frameworks (MOFs). Based on the material simulation technique, we proposed implanting a significantly positive-density ligand (DABA) to modify MIL-101 and constructing dual positive-charging centers to improve MIL-101 competitive adsorption of benzene VOCs over H2O vapors both thermodynamically and kinetically. The introduction of DABA containing two –NH2 groups with electrostatically positive charges into MIL-101 resulted in the formation of an open tetrahedral cage with a dual positive charging center. This facilitated strong N-H…π interactions with toluene molecules, leading them to accumulate firmly in MOF pores, and thus dramatically enhanced its adsorption capacity from 17 to 31 toluene molecules per unit cell compared to pristine MIL-101. Moreover, the open tetrahedral cage in D-MIL-101 preferentially captured toluene and occupied the strongest adsorption sites first, thus effectively preventing H2O entry into MOF pores to contact with hydrophilic metal sites. This realized high water resistance and toluene adsorption uptake under high humidity conditions. Results showed that D-MIL-101 had a high specific surface area of 2558 m2/g and a new microporous structure of 9.5 Å size. It presented higher toluene uptake of 4.69 mmol/g at lower vapor pressure of P/P0 = 0.013 and 298 K temperature, as well as 3.3 folds higher working capacity of toluene compared to pristine MIL-101 under 80 % RH. This study presents a novel approach for constructing hydrophobic MOFs using new positive charging ligands and delves deeper into the competitive adsorption of VOCs/H2O in MOF composites for large-scale applications.

Investigation of the incorporation of C60 into PC61BM to enhance the photovoltaic performance of inverted-type perovskite solar cells based on MAPbI3

Perovskite Solar Cells (PSCs) have managed to significantly capture attention by achieving efficiency values of 25.6% in a remarkably short period of around ten years. Each layer within the device plays a crucial role in the overall device efficiency when it comes to PSC production. PC61BM, a derivative of fullerene, is one of the most commonly used electron-transport layers (ETLs) in inverted-type PSCs. In this study, the improvement of the ETL was aimed by incorporating C60 into PC61BM, and the effects of the doped ETL on MAPbI3-based inverted-type PSCs were investigated. For inverted type PSCs which are fabricated under high humidity (40-60%) and room conditions (~25 °C), the power conversion efficiencies (PCEs) have boosted from 11.54% (for undoped PC61BM) to 13.40% (for C60-doped PC61BM). To comprehend the sources of improvement in the fabricated devices, a series of characterizations were carried out, including Current Density-Voltage (J-V), Hysteresis Factor (HF), Scanning Electron Microscope (SEM), and Atomic Force Microscope (AFM) measurements.

Preparation and temperature-controlled morphology of helical microrods composed of supramolecular α-cyclodextrin assemblies.

Significant efforts have been devoted so far to artificially fabricate supramolecular helical nano- and microstructures through the regulated assembly of biological and synthetic building blocks. However, the preparation of supramolecular helical structures with a regulated morphology remains challenging. Here, helical microrods composed of supramolecular α-cyclodextrin (α-CD) assemblies were fabricated by allowing an α-CD/1,1,1,3,3,3-hexafluoro-2-propanol (HFIP)/2-pentanol mixture to stand at 30-60 °C under high humidity conditions. The morphology could be controlled by temperature to produce helical microrods with a regulated pitch and length. These helical rods can be applied as optical devices, chiral separation devices and asymmetric catalysts.

Standardized agronomic practices for mechanical harvesting of the single-harvest garden pea in India

The field investigations were conducted at Vegetable Research Farm, Department of vegetable Science, Punjab Agricultural University, Ludhiana with the objective to standarize the agronomic practices for mechical harvesting of garden pea. Therefore, effect of different agronomic traits including time of sowing, spacing and sowing method on yield and its attributing traits were studied on single-harvest garden pea. The experiment was laid out in split-plot design with 30 treatments comprising five dates of sowing in main plots and 2 different planting methods (flat and bed) sown at three different spacing in subplots and replicated three times. The bed size was standardized according to front-loading width of the pea combine. Significant interactions were observed between the date of sowing and spacing for a number of pods per plant, green seeds per pod, green pod yield per plant, green pod yield per plot; date of sowing and sowing method for pod length; spacing and sowing method for plant height. However, for all the traits, there was non-significant 3-way interaction. The late sown (20th December) crop resulted in the least number of pods per plant, green seeds per pod, green pod yield per plant and green pod yield per plot which was due to high temperature and low relative humidity conditions at pod development and filling stage. It is concluded that the garden pea cultivar Punjab-89 sown on 5th November at the spacing of 20 × 7.5 cm on beds (bed width of 1.0 m) resulted in significantly highest green pod yield of 12.75 kg/9 m2 in the single harvest. Therefore, the 3 beds of 1 m width can be harvested together with pea combine (because combine has working front width of 3.1 m) results into maximum yield when pea crops is sown on 5th November @ 20 × 7.5 cm spacing.

HIGHLY STABLE PEROVSKITE FILM WITH IONIC LIQUID ADDITIVES FOR AMBIENT AIR DEPOSITION

Perovskite solar cells (PSCs) technology has emerged as a highly promising photovoltaic (PV) option due to remarkable advancements in power conversion efficiency (PCE). Nevertheless, the stability of PSCs continues to pose a challenge for commercialization, as factors such as moisture, oxygen, light, and temperature can lead to degradation during fabrication and actual use stage. The stability of the perovskite film is crucial for extending the device’s lifetime and performance. This research seeks to explore the degradation mechanism and improve the perovskite film’s stability by incorporating 1-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF4) and 1,3-dimethyl-3-imidazolium hexafluorophosphate (DMIMPF6) ionic liquids into a perovskite precursor using the two-step deposition technique in ambient air. The perovskite film’s degradation and PSCs’ stability were evaluated under high relative humidity conditions, averaging 73%RH without encapsulation. UV-visible spectroscopy results indicate that the most stable perovskite film, containing the BMIMBF4 ionic liquid additive, maintains its α phase perovskite structure for 144 hours without alterations in absorbance and persisted for over 336 hours before degrading into an undesirable δ phase perovskite. Furthermore, PSCs retained 74.1% of their initial PCE after 28 days of exposure to ambient conditions. This research offers promising findings for the large-scale fabrication of stable PSCs.

Characterisation of Novel and High Performing Double-Sided Microporous-Layers-Coated Gas Diffusion Layers for Polymer Electrolyte Membrane Fuel Cells

This study aims to experimentally evaluate the impact of a double-sided microporous layer coating on gas diffusion layers in terms of their key properties and fuel cell performance, in comparison to conventional single-sided coated gas diffusion layers (GDLs). Vulcan black and Ketjenblack were used as the carbon black materials. This was to investigate the sensitivity of the results with respect to the type of carbon black used. The results showed that the in-plane electrical conductivity is almost insensitive to microporous layer (MPL) loading and carbon black type. Furthermore, the electrical conductivity of all the MPL-coated GDLs are slightly lower than that of the uncoated GDL. The Ketjenblack black MPL samples were found to demonstrate higher gas permeability than the Vulcan black samples. The addition of the MPL resulted in a favourable shift in pore size distribution, with prominent micropores observed in both single- and double-sided MPL-coated GDLs. Contact angle measurements indicated a slight increase in the hydrophobicity with the addition of a microporous layer, but without significant differences between carbon black types or loading levels. Cross-sectional SEM images showed that there was a higher level of MPL penetration into the carbon substrate for the GDLs coated with Vulcan black as compared to a Ketjenblack coating. In situ fuel cell testing demonstrated the superior performance of the double-sided Vulcan black MPL-coated GDL under high humidity conditions, while the single-sided Vulcan black MPL-coated GDL exhibited better performance at low humidity conditions. All the above findings have been thoroughly discussed and justified.