Oxygen Precipitation Research Articles

Simultaneous dual modification of Li-rich Mn-based cathode in restraining oxygen release and structure distortion

Li-rich Mn-based cathode material is modified by a dual modification approach involving Ce, B co-doping, which regulates energy band and induces surface structure reorganization to suppress lattice oxygen precipitation and electrolyte corrosion, thereby improving the cell performance.

Rhodium and Rhodium-Alloy Films and Nanoparticles: Part I

Noble metals are key to various research fields and noble metal nanomaterials are directly relevant to optics, catalysis, medicine, sensing and many other applications. Rhodium-based nanomaterials have been less studied than metals such as gold, silver or platinum. There have been many improvements in characterisation tools over the years and knowledge about rhodium chemistry and nanomaterials is growing rapidly. Rhodium nanoparticles are widely used as catalysts for automotive emissions control and for hydrogen and oxygen precipitation reactions in electrolytic cells. Novel applications in electronics, anticancer drugs and aerospace are being revisited. In Part I of this two-part review, we cover different strategies for the synthesis of rhodium films and nanoparticles.

Ce and S co-doped NiFe based alloy nanocomposite prepared by one-step electrodeposition method for oxygen evolution reaction

It's still a challenge to design reasonably efficient catalyst using non-noble metal for the oxygen evolution reaction (OER). In this paper, we use a simple one-step electrodeposition method to load Ce and S co-doped NiFe amorphous alloys onto Cu(OH)2 nanorod arrays. The excellent oxygen electrocatalytic performance of the catalyst NiFeCeS/Cu(OH)2/CuF is attributed to the electronic environments of the active sites of Ni and Fe regulated by heteroatomic sulfur and cerium, which promote the transfer of the oxygen precipitation intermediates to the higher valence states. Meanwhile, the highly conductive substrate accelerates the electron transfer efficiency of the catalyst material, and the loose nanostructure increases the specific surface area, exposing more active sites. NiFeCeS/Cu(OH)2/CuF shows outsanding electrocatalytic activity for oxygen evolution with a low overpotential of 227 mV at a current density of 10 mA cm−2 in alkaline medium. Moreover, the nanocomposite catalyst also exhibits rapid reaction kinetics and long-term stability and durability. In this work, an efficient oxygen precipitation catalyst is reported, which indicates that non-precious metal-based electrocatalysts have great potential for application in water electrolysis and provides a basis for the rational design and synthesis of nanorod array catalysts with unique structures.

Construction of n-type homogeneous to improve interfacial carrier transfer for enhanced photoelectrocatalytic hydrolysis

Photoelectrocatalyzed hydrogen production plays an important role in the path to carbon neutrality. The construction of heterojunctions provides an ideal example of an oxygen precipitation reaction. In this work, the performance of the n-n type heterojunction CeBTC@FeBTC/NIF in the photoelectronically coupled catalytic oxygen evolution reaction (OER) reaction is presented. The efficient transfer of carriers between components enhances the catalytic activity. Besides, the construction of heterojunctions optimizes the energy level structure and increases the absorption of light, and the microstructure forms holes with a blackbody effect that also enhances light absorption. Consequently, CeBTC@FeBTC/NIF has excellent photoelectric coupling catalytic properties and requires an overpotential of only 300 mV to drive a current density of 100 mA cm−2 under illumination. More importantly, the n-n heterojunction was found to be effective in enhancing charge and photogenerated electron migration by examining the carrier density of each component and carrier diffusion at the interface.

Irrigation‐induced evaporative water loss in a glacially derived soil site

AbstractWorldwide, significant agricultural activities take place where groundwater is used for irrigation and water losses occur due to evaporation. Water loss through evaporation is affected by the soil type, local climate and most likely crop type. Previous studies from arid regions demonstrated the utility of oxygen and hydrogen isotopes in estimating evaporative water loss during return flow back to an aquifer. This study examined the region around Kalamazoo, Michigan, United States, where the soil is formed from glacial sediments and the region experiences a temperate climate. The present study is applicable to agricultural practices in many parts of the world that are in a temperate climate zone. The study area primarily uses centre‐pivot systems supplied by wells. Water samples were taken periodically from wells close to centre‐pivot irrigation systems. Knowledge of isotope ratios in precipitation, the primary source of groundwater recharge is a prerequisite for this study. The distribution of oxygen and hydrogen in local precipitation, the so‐called Local Meteoric Water Line, is available based on several years of measurements. An evaporative model of the isotope data indicates water loss from evaporation to be in the range of 14% and 6%. This is less than what was estimated for arid region zones and is perhaps also due to the well‐drained nature of the regional soil which promotes rapid infiltration lowering evaporation. Evaporative loss was greater at wells near cornfields than at wells that supplied other crop types. Little expected correlation between the groundwater isotope data and chloride concentration is attributable to an external input of chloride from road salt used in winter months.

Precipitation Oxygen Isotope Changes Over East Asia Driven by Sea Surface Conditions During the Last Glacial Maximum

AbstractThe seasonal changes in East Asian monsoon precipitation during the Last Glacial Maximum (LGM, 23,000–19,000 years B.P.) and its isotopic expression remain ambiguous. This study investigates changes in the seasonal precipitation δ18O (δ18Op) over East Asia during the LGM relative to the preindustrial (PI) and the underlying mechanisms using an isotope‐enabled atmospheric general circulation model. We show more depleted δ18Op in summer and a meridional tripolar δ18Op pattern in winter during the LGM compared to the PI. The depletion of summer δ18Op resulted from stronger upstream convective rainout due to the intensification of the Intertropical Convergence Zone. In contrast, the mechanisms for winter δ18Op changes were more complicated. With a series of sensitivity tests, we demonstrate that sea surface temperature controlled δ18Op changes across the whole of East Asia in summer and in the southern part of East Asia in winter. The depletion of winter δ18Op in central China arose largely from the suppression of droplet evaporation due to higher snow fraction. Our work provides important insights into the aspect of seasonal isotope changes during the LGM and may help facilitate an improved level of paleoclimatic interpretation of speleothem δ18O records from East Asia.

Progress in the Synthesis Process and Electrocatalytic Application of MXene Materials.

With their rich surface chemistry, high electrical conductivity, variable bandgap, and thermal stability, 2D materials have been developed for effective electrochemical energy conversion systems over the past decade. Due to the diversity brought about by the use of transition metals and C/N pairings, the 2D material MXene has found excellent applications in many fields. Among the various applications, many breakthroughs have been made in electrocatalytic applications. Nevertheless, related studies on topics such as the factors affecting the material properties and safer and greener preparation methods have not been reported in detail. Therefore, in this paper, we review the relevant preparation methods of MXene and the safer, more environmentally friendly preparation techniques in detail, and summarize the progress of research on MXene-based materials as highly efficient electrocatalysts in the electrocatalytic field of hydrogen precipitation reaction, nitrogen reduction reaction, oxygen precipitation reaction, oxygen reduction reaction, and carbon dioxide reduction reaction. We also discuss the technology related to MXene materials for hydrogen storage. The main challenges and opportunities for MXene-based materials, which constitute a platform for next-generation electrocatalysis in basic research and practical applications, are highlighted. This paper aims to promote the further development of MXenes and related materials for electrocatalytic applications.

Deep reconstruction of Ni-doped CoOOH under industrial conditions for efficient oxygen evolution

Hydrogen production by water electrolysis is considered to be economical and environmentally friendly. Encouraging the reconstruction of electrocatalysts during the oxygen evolution reaction (OER), which produces a large number of active species with high activity, might be viewed as a promising technique for increased activity. In this work, thermally induced complete reconstructions (TICR) are used to create (oxy)hydroxide with low crystallinity and abundant boundary/vacancy from molybdate precatalysts. The obtained Ni-doped CoOOH (CMO1200-90/NF) with boundary/vacancy demonstrates the efficient electrocatalytic activity for OER. An oxygen precipitation overpotential of 299 mV (100 mA cm−2) is exhibited, while the durability of this structure is verified in a strong corrosive environment (1 M KOH) with a long-term stability of 100 h. Compared with Ni-doped CoMoO4 precatalyst, the overpotential is reduced by 102 mV at 100 mA cm−2. During the hydrothermal process, trace amounts of Ni elements are doped and have a synergistic effect with Co to induce the modulation of electronic structure. This work investigates the phenomenon of thermally induced and highlights the commercial potential of deep reconstruction catalysts in high-temperature water electrolysis.

Effects of Nitrogen Doping on Pulling Rate Range of Defect-Free Crystal in CZ Silicon

We investigated the effect of nitrogen doping on the pulling rate range of defect-free crystal in silicon with a diameter of 200 mm. It was found that the pulling rate range of defect-free crystal in nitrogen-doped Czochralski silicon is wider and the pulling rate (defect free) is lower than it is in non-nitrogen-doped Czochralski silicon. Under the experiment, the pull rate was from 0.67 mm/min~0.58 mm/min to 0.65 mm/min~0.54 mm/min. To further confirm the above experimental analysis, a numerical simulation process of nitrogen-doped Czochralski and non-nitrogen-doped Czochralski in an industrial system was performed. The V/G value along the S/L interface was the same for both models, but the distribution of Cvi (concentration of vacancy–concentration of self-interstitial) for nitrogen-doped Czochralski crystal silicon was more uniform and flat in a nitrogen-doped single crystal. Furthermore, the nitrogen-doped Czochralski crystal silicon had a smaller void size and a higher oxygen precipitation density. The experimental results are in good agreement with the numerical simulation results.

Moisture sources and climatic effects controlling precipitation stable isotope composition in a western Mediterranean island (Pianosa, Italy)

The Mediterranean basin is indicated as a hot spot of climate change, which is an area whose climate is especially responsive to variations. The insular environment is one of the most threatened by the current climate change, especially in terms of drought events, with serious consequences for water scarcity and water stress. This issue is even enhanced in small islands, whose ecosystems are among more sensitive to climatic changes and water availability. The stable isotope composition of hydrogen (δ2H) and oxygen (δ18O) in precipitation is globally recognized as a powerful natural tracer in the water cycle and represents the starting point to investigate hydrological processes. The understanding of the prevailing factors that drive the isotopic variability of precipitation in the Mediterranean is therefore essential to unravel the hydrological processes and to ensure proper and sustainable management of potentially vulnerable resources to climate change. Here, we discuss the results of multi-year isotopic monitoring in the period 2014–2021 of monthly precipitation collected on Pianosa Island (Italy), a small island located in the northern Tyrrhenian (western Mediterranean). The lower slope and intercept of the Local Meteoric Water Line of the island compared to the Global Meteoric Water Line indicated warmer and drier climatic conditions, suggesting the existence of sub-cloud evaporation processes of raindrops during precipitation, especially in summer. The mean δ18O of precipitation was lower with respect to other sites placed at higher elevation in this Mediterranean region, due to the lack of summer precipitation which were generally enriched in heavy isotopes. Temperature and amount effects may explain part of the δ18O variability observed at the monthly and seasonal scale. An HYSPLIT-based moisture uptake analysis indicated the area between the western Mediterranean basin, Italy, and the Adriatic Sea as the region that supplied most of the humidity associated with monthly precipitation samples on Pianosa Island. Less moisture was picked from the northwestern areas of Europe, the North Atlantic Ocean, the proximal Atlantic Ocean, the Iberian Peninsula and North Africa. Consistently with the rainout effect, the higher the moisture fraction picked from the more proximal regions, the more positive the δ18O of precipitation occurring on Pianosa Island; conversely, the higher the percentage of moisture sourced from more distal regions, the more negative the δ18O. A multiple linear model was proposed to predict the δ18O of monthly precipitation from temperature, precipitation amount and moisture origin data, which explained 45% of the δ18O variability. The deuterium excess variability on the island was partly controlled by the local climatic variables, whose effect potentially modifies the original d-excess signature imprinted at the moisture source. No relationship was found between the precipitation deuterium excess and moisture sources, suggesting that more attention should be paid when using the deuterium excess as a tracer of moisture origin, especially in the Mediterranean.

Stable isotopes of oxygen and hydrogen in precipitation and river water in Georgia

Abstract The article presents the first comprehensive evaluation of the isotopic composition of precipitation and runoff in Georgia. It is based on data from the monitoring of δ18O and δ2H in monthly precipitation at eleven precipitation stations and monthly runoff from five large, mostly nested catchments in Georgia, collected between the years 2013 and 2022. The data represent different climatic and altitudinal conditions ranging from the wet western part of Georgia affected by the Black Sea to the dry eastern part of the county presumably affected also by the air masses from the Caspian Sea. Specific conditions affecting the isotopic composition of precipitation and river water seem to occur close to the main ridge of the Greater Caucasus Mountains. We defined the National Meteoric Water Line (NMWL) and the National River Water Line (NRWL) for Georgia as well as the Local Meteoric Water Lines (LMWLs) and River Water Lines (RWLs) for individual precipitation stations and river gauges and investigated their slopes and intercepts. Altitude gradients of δ18O and δ2H in the rivers were similar to those in precipitation (–0.16‰ and –1.2‰ per 100 m of altitude for δ18O and δ2H, respectively). The rivers were supplied from precipitation of the colder part of the year (November/December to March/April) while the isotopic composition of precipitation in the remaining warmer part of the year was clearly detached from that of the rivers. The isotopic signal in precipitation was dampened in the rivers by a factor of 5–6. The scaled line-conditioned excess (lc-excess*) did not indicate any significant deviations of river waters from meteorological conditions in the catchments.

Preparation of porous iridium-ruthenium-based acidic water oxidation catalyst by ascorbic acid reduction and evaporation

Green hydrogen is the ultimate direction for energy development technology. Hereon, the porous materials of promoted iridium-ruthenium-based catalyst were prepared by ascorbic acid reduction and evaporation drying methods. The unsupported iridium ruthenium-based catalysts were porous structures, characterized by scanning electron microscopes (SEM). In 0.5 mol·L−1 H2SO4, the electrochemical oxygen precipitation reaction overpotential was only 251 mV at 10 mA·cm2, compared to commercial 303 mV. The polarization overpotential was not significantly reduced, after 20 000 cycles of accelerated cyclic aging experiments. The porous structure of the iridium-ruthenium-based catalysts showed higher catalytic activity for oxygen precipitation than the commercial IrO2(ZrO2) catalysts. Porous materials could improve the activity of catalysts, which provides a good research idea for the synthesis of electrocatalysts.

Synergistic mechanism of B doping and NiO loading on the excellent PEC performance and high stability of TiO2 nanotube photoanodes

The severe photogenerated charge recombination rate, poor visible light utilization and slow oxygen precipitation kinetics are the technical bottlenecks limiting the photo-electrolysis of TiO2 nanotube array (TNAs) photoanode for hydrogen production from water. To solve these problems, NiO nanoparticles were uniformly loaded into B-doped TNAs by the CV method. It is found that B-doping improves the energy band structure of TNAs, and doping-induced surface defects could become traps for photogenerated carriers to substantially improve the charge separation efficiency of the bulk phase. The P-N junctions formed between TiO2 anatase and NiO nanoparticles not only promoted the OER kinetics at the interface but also greatly improved the surface carrier separation efficiency of the catalyst, as well as ensured the stability and activity of the B-doping-induced surface defects. Moreover, the carrier concentration and visible light absorption properties of TNAs were enhanced and improved. Due to the synergistic effect of B doping and NiO loading, the bulk charge separation efficiency and surface charge separation efficiency of NiO/BT (B doping and NiO loading TNAs) were as high as 88.9 and 82.4%, respectively, at 1.23 V vs. RHE, and the photocurrent density reached 2.05 mA/cm2, which was 10 times higher than that of pure TNAs.

Effect of in-plane Mott-Schottky on the hydroxyl deprotonation in MoS2@Co3S4/NC heterostructure for efficient overall water splitting

The development of clean energy sources such as hydrogen is indispensable for achieving the long-term goal of carbon neutrality by the mid-century. The utilization of renewable energy for power generation to electrolyze water for hydrogen production is one of the most desirable green hydrogen production methods. The cathode side of the decomposing water undergoes the oxygen precipitation reaction, and the oxygen precipitation mechanism can be divided into the adsorbed evolution mechanism (AEM) and lattice oxygen oxidation mechanism (LOM). Based on the adsorbed evolution mechanism (AEM), the deprotonation (DeP) process involving multiple electron transfers is central to determining the oxygen release. DeP is essentially a proton-transfer process that allows for the establishment of a bifunctional catalyst system with both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Consequently, an all-transition-metal-based MoS2@Co3S4/NC heterostructure was designed and constructed in this study for the efficient total decomposition of water. The MoS2@Co3S4/NC catalyst achieved the HER and OER current densities of 10 mA cm−2 at the low overpotential (56 mV, 243 mV) and showed excellent long-term durability among all samples. The Mott-Schottky effect is considered the driving force for the HER and DeP in the OER. This study proposes a rational design for bifunctionalized non-precious metal electrolytic water catalysts using the Mott-Schottky effect as a criterion.

Orthorhombic phase induced ultra-low operation voltage in La-doped BiFeO3 resistive switching devices

In this study, the effect of La doping on the resistive switching properties of BiFeO3 (BFO) is systematically discussed. It was found that La doping can not only inhibit the volatilization of Bi and thus diminish the intrinsic oxygen vacancy of BFO, but also improve the lattice symmetry of BFO for generating orthorhombic phase BFO. To confirm these microstructural changes and their relation to the resistive switching properties of BFO, the phase structures, chemical compositions, microstructures, energy band structures, and interfacial features of BFO with different La-doping concentrations are characterized. The resistances of BFO devices with different La doping concentrations also show significant differences, especially, the 15 at. % La-doping BFO device exhibits ultra-low operation voltage of only −0.15 V and good cycling consistency due to the integration of low oxygen vacancy concentrations and precipitation of the orthorhombic phase. The multiple effects of La doping on the resistive characteristics of BFO discussed in this paper provide a reference for the application of BFO in the field of resistive memories.

AlPO4-Li3PO4 dual shell for enhancing interfacial stability of Co-free Li-rich Mn-based cathode

Li-rich Mn-based cathode materials (LRM) have attracted extensive attention as key cathode material for achieving high energy density in lithium ion batteries. However, the irreversible oxygen precipitation and structural transformation during its cycling process, resulting in capacity and voltage degradation have heavily hindered practical applications. The Co-free Li-rich Mn-based cathode material Li1.2Ni0.185Mn0.585Fe0.03O2 by the modified Pechini method, the AlPO4-Li3PO4 double shell was formed in situ on its surface. The AlPO4 protective layer formed by the highly electronegative (PO4)3- with not only effectively inhibits the precipitation of surface oxygen, but also suppresses the interfacial side reactions and transition metal dissolution, thus raising the cycling performances. The formation of the outer Li3PO4 helps to remove the residual Li+ on the surface, accelerates the diffusion and charge transfer process of Li+ at the electrode/electrolyte interface. The synergistic modification of the AlPO4-Li3PO4 dual shell can significantly improve the cycling stability and rate performance. In particular, the 3% modified sample with a capacity retention of 74.8% after 200 cycles at 0.2 C. The first discharge specific capacity is 260.73 mAh g-1 at 0.1 C, and the initial coulombic efficiency reaches 84.96%. The lithium-ion full cell employing 3% and graphite exhibit a specific energy density of 440 Wh kg-1 at 0.1 C, and shows the best cycling stability with 78.3% capacity retention over 100 cycles at 1 C.

Isotope Composition of Natural Water in Lake Onega Basin

In 2009–2018, the isotopic composition of oxygen and hydrogen in the atmospheric precipitation, groundwater and river and lake water of Lake Onega basin was studied. The weighted annual isotope composition of precipitation at Petrozavodsk was δ18O = −11.7‰ and δ2H = −84‰ and varied from −30.9 to −4.1‰ for δ18O and from −23 to −22‰ for δ2H. The isotopic composition of the water in Lake Onega was relatively uniform from −11.5 to −9.3‰ for δ18O and from −85 to −71‰ for δ2H. In the bays, the isotopic composition of the water varied more substantially than in the central part of the lake due to the river runoff during springtime flooding. In late summer, the concentrations of deuterium and oxygen-18 increased in the lake water, and figurative points on the δ2H vs. δ18O diagram shifted above the meteoric line. The absorption of the isotopically heavy summer precipitation and disequilibrium isotope fractionation during evaporation led to the enrichment of the lake water by heavy isotopes. Experiments were conducted to estimate the evaporation influence on the isotope enrichment of the residual water, and a comparison of the obtained isotope data with the experimental function showed that commonly, about 4% and up to 12% of water was lost during the spring and summer, respectively. In the water of the tributaries, the abundance of the deuterium and oxygen-18 varied in a wider scale than in the lakes, from −14.4 to −9.1‰ for δ18O and from −102 to −73‰ for δ2H. An evaporation loss of up to 35% was found for the rivers in late summer, and this value was proportional to the area of lakes and wetlands in the elementary watershed. The initial isotope composition of the water in the tributaries prior to evaporation was estimated to be δ18O ≈ −14.1‰ and δ2H ≈ −103‰ on average and crossed the approximation and meteoric lines. This estimation was close to the average composition of the groundwater, i.e., δ18O ≈ −13.4‰ and δ2H ≈ −94‰ on the Lake Onega catchment. The slightly increased isotope depletion of the calculated composition in the initial river water in comparison with the groundwater was the result of the contribution of the spring snowmelt water, which had a significant influence on the lake water balance.

Simulation study on 300mm monocrystalline silicon celerity single crystal

Since entering the 21st century, the survival and development of mankind are faced with great challenges and great opportunities. With the decrease of petroleum, coal, natural gas and other resources, a large number of harmful products generated in the combustion process of fossil fuels have caused incalculable adverse effects on human living environment. Thermal stress in crystals is one of the key factors affecting the properties of solar level monocrystalline silicon. In this paper, the relationship between the heat loss mode and the stress in crystal is studied. If carbon is introduced into the crystal growth process, it will promote the formation of oxygen precipitation and SiC precipitated phase, resulting in increased stress in the crystal, thus affecting the quality of monocrystalline silicon. The distribution of carbon impurities in the melt is closely related to the convection behavior of the melt. The carbon atoms in the atmosphere diffused into the melt mainly through the free surface area near the crucible wall. By adjusting the structural parameters of symmetric magnetic field and asymmetric magnetic field, the convection intensity in the carbon atom doped region can be suppressed, the thickness of carbon atom diffusion layer can be increased, and the oxygen content and distribution uniformity in the crystal can be controlled by magnetic pull technology to improve the crystal quality.

Environmental drivers of precipitation stable isotopes and moisture sources in the Mongolian Plateau

Τhe absence of precipitation-isotope stations in the wide flatland of the Mongolian Plateau (MP) hinders the analysis of precipitation processes. For this reason, a precipitation-isotope station was established in Erenhot in 2015. Based on precipitation samples collected during all precipitation events between January 2015 and December 2019, we analyzed the temporal variations of stable isotopes (δ2H, δ18O) in precipitation and their influencing factors, including meteorological factors, sub-cloud evaporation, and moisture sources. Oxygen and hydrogen isotopes in precipitation in Erenhot are richer than those in Ulaanbaatar, which is situated close to the mountains and depleted compared to, e.g., Baotou. In Erenhot, oxygen and hydrogen isotopes in precipitation are controlled by the temperature effect, similarly to Ulaanbaatar, but also by the amount effect in summer. The low slope of the local meteoric water line indicates that raindrops have undergone sub-cloud evaporation. The annual mean sub-cloud evaporation fraction was 5.2% from 2015 to 2019, while sub-cloud evaporation fraction was highest in summer (7.5%). Sub-cloud evaporation is mainly correlated by relative humidity, precipitation amount, regional (pan) evaporation, and air temperature. Relative humidity has the greatest effect and masks the effect of air temperature. The study area is mainly controlled by the west wind and winter monsoon, which brought 75.6% of the total precipitation with −7.75‰ δ18O. During summer, the Pacific monsoon resulted in 13.5% precipitation with −10.34‰ δ18O in the study area, while the Indian monsoon had negligible impact. Except for moisture advection, the moisture recycling fraction accounted for 11.1% of local precipitation, with −10.32‰ δ18O. This study compensates for the lack of global network of isotopes in precipitation (GNIP) stations in the MP, reveals the MP precipitation-isotope signatures and their influencing factors, and provides basic precipitation-isotope information for researching the distribution of precipitation-isotope signatures in Asia and the water cycle in the MP.

The Excitation Efficiency for Dislocation-Related Luminescence Centers in Silicon with Oxygen Precipitates

The Excitation Efficiency for Dislocation-Related Luminescence Centers in Silicon with Oxygen Precipitates