High Temperature Water Research Articles

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.

An investigation of the density of nano-confined subcritical/supercritical water

In various applications such as supercritical water gasification, oil and gas production, and energy harvesting and storage, subcritical/supercritical water is often confined within material pores. Investigating the density and critical parameters of high-temperature and high-pressure water in confined spaces can help us better understand the behavior of water within the pore space. In this study, a topological model consisting of two baths and a carbon nanotube (CNT) is built to examine the effect of temperature (300 K & 600–1173 K), pressure (1 atm & 20–30 MPa), and tube diameter (9.49–50.17Å) on confined density, and used machine learning (ML) to develop a predictive application (APP). The ML model demonstrates excellent predictive performance, achieving an R2 of 0.9962 on the test set. Furthermore, the mean impact value (MIV) is used to evaluate the impact of independent variables on confined density, and find that temperature has the most significant effect. The results indicate that the critical temperature and pressure of water confined within different CNTs are not significantly different from those of bulk water, but the confined critical density is slightly lower than the bulk critical density.

Experimental and theoretical investigation on the energetic and economic performance of low-temperature cascade air-source heat pump considering the effects of cascade heat exchanger

Air-source heat pump (ASHP) is wide used for its carbon neutrality. In cold climates, to ensure good efficiency and stability, cascade ASHP is a promising technology for high-temperature water application, such as space heating boilers retrofit. Cascade heat exchanger is a key component in cascade ASHP. However, there are few experimental studies on the effects of its area on system energetic, economic, and environmental performance under low ambient temperature and high water-supply temperature, which is essential for system improvement and application. Focusing on this research gap, this paper carries out experiment of cascade ASHP system performance and conducts analysis on system suitability based on recurrent Neural Network. To fairly compare system performance in different cold climate cities with different cascade heat exchanger areas, conversion factor γ is proposed and used in the analysis. The results show total energy consumption of compressors decreases the most in New York (21498 MJ) and least in Shenyang (9414 MJ) as cascade heat exchanger areas increases from 0.6 to 1.6 m2. Similarly, the system in New York shows the most significant reductions in carbon emissions (2701 kg/year) and total annual cost (225$), while that in Shenyang shows the smallest drop of 1277 kg/year and 118$, indicating it’s more meaningful to increase cascade heat exchanger area in a city with longer heating period. The results also show the COP varies significantly across cities, strongly correlated with average ambient temperature. The increase in COP slows down when cascade heat exchanger area reaches 1.6 m2, indicating even larger area is not recommended. These findings provide a foundation for improving and applying cascade ASHP in cold climates.

The structure dependence of grain boundary passivation of Alloy 690 in high temperature water

The oxidation behavior of grain boundaries (GBs) was investigated on Alloy 690 after exposure to simulated pressurized water reactor primary water. The tendency to form passive film above GB is positively related to Cr diffusivity along GB which is determined by GB structure. Highly-ordered GB like twin boundary is subject to penetrative oxidation as Cr diffusivity is very low. GBs with misorientation angle θ ≤17.4° can't support fast diffusion of Cr either and also show penetrative oxidation. When θ ranges between 17.4° and 28.7°, Cr diffusivity is enhanced a little and GB shows unstable passivation. Meanwhile, the Cr diffusivity along GB is also related to the atomic packing density of GB planes. GB with higher atom packing density exhibits lower Cr diffusivity and deeper intergranular oxide depth. As θ increases above 28.7°, Cr diffusion is fast enough to support the formation of protective film above GB.

A dynamic energy budget model for black rockfish Sebastes schlegelii: Parameterization and application in marine ranching areas, Yellow Sea, China

Marine ranching has become a powerful tool for coastal habitat restoration, ecosystem conservation and stock enhancement. With increasing development of marine ranching in recent years, it has attracted wide attentions for fishery management and sustainability. The stock of black rockfish Sebastes schlegelii has undergone a serious decline due to overfishing in the past few decades, but has considerably recovered recently in marine ranching areas along the coasts of the Northwest Pacific. Appropriate management of the species is essential for marine ranching development. In this study, a dynamic energy budget (DEB) model of S. schlegelii was developed and applied in the Xixiakou, Changdao and Qiansandao marine ranching areas, Yellow Sea, China. The effects of food availability and water temperature on its growth and reproduction were quantified. The model was parameterised following the AmP procedure, which resulted in mean relative error of 0.123 and symmetric mean square errors of 0.134. The application of the model has showed that the model could reproduce the growth trajectories of both length and weight at each of the three marine ranching areas without site-specific calibration. The growth rates of S. schlegelii showed that Qiansandao > Changdao > Xixiakou in both length and weight. Temperature and food availability are the main contribution to the variations of growth amongst sites. In Qiansandao, the fast growth and maturation of the species correspond to relative high water temperature and sufficient food availability. Food availability limited growth and reproduction of S. schlegelii in Xixiakou, which indicated that the stock density in the areas might be close to the carrying capacity. The earlier maturation was a result of higher temperature and more food supply in Qiansandao than in Changdao and Xixiakou. Fishing and recapture in marine ranching areas should be adjusted to flexibly avoid spawning periods. The presented model is applicable to other marine ranching areas and coastal habitats. It provides an important component of ecosystem management approaches to estimate the ecological carrying capacities. This study provides information about the stock enhancement potential of coastal environments and a powerful tool for sustainable coastal fisheries management.

Study on the working medium of high temperature heat pump suitable for industrial waste heat recovery

In order to find a high-temperature heat pump (HTHP) working medium suitable for industrial waste heat recovery, this paper theoretically analyzes the thermodynamic properties of six refrigerants, including the coefficient of performance (COP), condensation pressure, compression ratio, heating capacity, exhaust temperature, and compressor power consumption. Based on the theoretical analysis results, environmental effects and the temperature range of industrial waste heat, MC-1 can be considered as a suitable working medium for high-temperature water source heat pump. The thermodynamic performance of MC-1 was experimentally studied and compared with that of HFC245fa and F-1 refrigerants. The results show that when the outlet water temperature of the condenser changes from 65 to 110 ℃ and the temperature lift is 35 ℃, the coefficient of performance of MC-1 varies from 4.24 to 5.05, which is much higher than that of both HCFC245fa and F-1. When the outlet water temperature of the condenser varies from 95 to 100 ℃, the average coefficient of performance of MC-1 is 16.2% higher than F-1 and 18.0% higher than HCFC245fa. The relative deviation between the theoretical calculation results and the experimental results of the main thermodynamic performance parameters does not exceed 10%, indicating that the theoretical results are reliable. Therefore, MC-1 can be recommended as the working medium for high-temperature heat pump with a single-stage cycle.

An investigation of water gas shift reaction in a Pd-alloy membrane reactor with an optimized crossflow configuration

In this study, the performance of a high-temperature water gas shift reaction (WGSR) using a Fe-Cr catalyst along with a Pd alloy membrane was simulated by computational fluid dynamics (CFD). The influences of using Pd membranes, catalytic layer thickness ratio (R/R0), Reynolds number, and steam-to-CO ratio (S/C) on the reaction were investigated by comparing CO conversion and hydrogen recovery (HR). In the CFD simulation, one-tube and four-tube systems were simulated at 500 °C. This study also compared the performance between tandem and optimized configurations. The results show that the CO conversion can be improved up to 22.9% when the WGSR reactor system uses a Pd membrane compared to the system without a Pd membrane. The system has the best hydrogen recovery performance at S/C = 4 and R/R0 larger than 1.5. At Re=5, the optimized configuration for CO conversion has better performance when R/R0 is larger than 1.75. Compared to the tandem configuration, the optimized configuration also shows better performance for HR at every R/R0. The results indicate that a Pd membrane and optimized configuration can significantly improve CO conversion and that R/R0 and S/C optimization is very important for effective reactor performance.

Mechanistic understanding of the localized corrosion behavior of laser powder bed fused 316L stainless steel in pressurized water reactor primary water

The laser powder bed fused (LPBFed) stainless steels showed anomalous and localized corrosion behavior in the nuclear reactor high-temperature water compared to their wrought counterparts, which affects their performance during plant operation. In this study, advanced microstructural characterization was performed on LPBFed 316 L sample along with wrought 316 L sample after corrosion tests to understand the underlying mechanisms. The results showed that an inhomogeneous/discontinuous inner oxide layer formed on LPBFed 316 L, in contrast to the continuous inner oxide layer on the wrought 316 L specimen. This discontinuous inner oxide layer was identified to consist of Cr-enriched nano-sized spinel oxide and the barrier layer features a Ni-enriched hexagonal close-packed Laves phase. Localized/preferential oxidation was found to occur along the cellular walls which were tangled with high density dislocations and decorated with Mn and Si-enriched nano-sized precipitates, and the nano-precipitates were observed in the core of dispersed Cr-enriched inner oxide crystals.

Investigation of the operation characteristics and optimization of an alkaline water electrolysis system at high temperature and a high current density

Increasing the operating temperature of water electrolysis is an effective way to improve its performance. When the available region of the operating current density is extended, the stack can generate an increased amount of hydrogen. This can directly contribute to green hydrogen being highly competitive compared to other kinds of hydrogen. In this study, numerical analysis was conducted to investigate and optimize the operational characteristics of alkaline water electrolysis (AWE) under high temperature and high current density conditions. The numerical model of the AWE developed in our previous study has been upgraded by considering the crossover of hydrogen gas through the membrane to more accurately determine the Faraday efficiency of hydrogen production and the available safe operating range. Simulation results show that saturated vapor generation significantly affected the performance of both stack and system components in high-temperature environments. Therefore, pressurization is important to ensure the high efficiency of high-temperature water electrolysis, but it must be appropriately adjusted in consideration of gas crossover. In this study, the highest efficiency of 78.52% was captured at 120 °C and 10 bar for 1 A/cm2 operation.

Harvesting freshwater from atmospheric air using thermal energy storage enabled solar air heater

Fresh water resources are scarce worldwide, and prevailing water harvesting systems face limitations of nighttime operations, high regeneration temperature and limited water yield. To address such issues, a novel system that integrates thermal energy storage unit for harvesting fresh water from atmospheric air is built and experimentally investigated under the ambient conditions. The system includes 4.86 m2 both ends open evacuated tube collector solar air heater to produce high regeneration temperature. Additionally, it incorporates a standalone for water vapor condensation. The performance of the system is compared using two different solid desiccant materials based on energy, exergy, environmental and economic analyses. The system using silica gel harvests 3.75 L/day of fresh water at a cost of 0.13 $/L with water harvesting coefficient of 0.76, while from molecular sieve, 3.41 L/day was harvested at 0.15 $/L with water harvesting coefficient of 0.64. From silica gel, the system reported the maximum thermal, overall and exergy efficiencies of 62.22 %, 10.29 % and 2.31 %, respectively, while from molecular sieve it was 59.12 %, 9.53 % and 2.08 %, respectively. The reports of water sample confirm that the harvested water from both the desiccant materials is good and safe for domestic consumption.

IMPACT OF DEICING SALT ON THE PERFORMANCE OF ASPHALT MIXTURES IN NORTHWEST CHINA: AN INVESTIGATION INTO MECHANICAL PROPERTIES AND INFLUENTIAL FACTORS

Currently, the primary form of high-grade highways is constituted by asphalt concrete pavement. Winter conditions often result in ice and snow accumulation on these pavements, precipitating severe traffic incidents. Statistically, around 15%-30% of such incidents are directly linked to icy and snowy conditions. Hence, when roads are laden with ice and snow, the most cost-effective and efficient countermeasure remains the dispersal of deicing salt onto the road surface. Particularly in China's northwestern region, which experiences low precipitation and consistent droughts, the deicing salts applied during winter aren't diluted or transported away by water flow. Consequently, the soil surrounding the roads retains a higher concentration of deicing salts than other regions, leading to a pronounced impact on the pavement's service life. This investigation aims to experimentally emulate the impact of this high-salt environment on the mechanical properties of asphalt mixtures, followed by an analysis of the crucial factors that influence the asphalt mixtures' durability. The current study employs measures such as high-temperature rut testing, Marshall water immersion testing, and freeze-thaw splitting testing to investigate the damage patterns of mechanical properties in asphalt mixtures under varying grading, diverse deicing salt solutions, and differing frequencies of dry-wet cycles. In addition, the study employs grey correlation entropy analysis to ascertain the interdependence among factors influencing the performance of asphalt mixtures. The findings reveal that after undergoing 0, 5, 10, 15, 20, 25, and 30 dry-wet cycles in solutions of 20% industrial salt (NaCl), 15% urea (CH4N2O), and 20% anhydrous ethanol (CH2CH3OH), both the high-temperature stability and water stability of asphalt mixtures with AC-13 and AC-16 gradings displayed varying levels of decline. Overall, an enhancement in the fine aggregate percentage in asphalt mixtures can augment the asphalt concrete's resistance to deicing salt erosion. As per the grey correlation entropy analysis, gradation variances exerted the most significant impact on diverse mechanical properties, followed by the type of deicing salt solution, with the least significant impact attributed to the frequency of dry-wet cycles. Thus, judicious selection of road materials and structural design can effectively counter the erosive action of deicing salts, thereby enhancing the service life of the road surface.

Integration of booster heat pumps in ultra-low temperature district heating network: Prototype demonstration and refrigerant charge investigation

Decentral booster heat pumps (BHPs) integrated in ultra-low temperature district heating (ULTDH) systems are deemed a sustainable solution for low-carbon building systems. The performance of BHPs is critical for the implementation of ULTDH systems. In this study, we experimentally investigate the effect of refrigerant charge on temperature, pressure, system coefficient of performance (COP), and heating capacity to evaluate the operability and sensitivity of ULTDH. A performance-guaranteed range of refrigerant charge is proposed to ensure the feasibility of the system. We also analyse the component-level exergy destruction and the system-level exergetic efficiency of a BHP prototype. The exergetic efficiencies range from 24.9 % to 33.4 % under operational conditions for ULTDH. The condenser and evaporator's exergy destruction is influenced by the temperature profiles on both sides, suggesting the potential to improve BHP performance by tailoring operating parameters. Additionally, the return water temperature significantly affects the system COP when the domestic hot water supply temperature is fixed. Within the allowable range of return water temperature, BHP operation with high evaporator outlet water temperature can improve the overall efficiency of the ULTDH system.

Long-term removal of perfluoroalkyl substances via activated carbon process for general advanced treatment purposes

Granular or powdered activated carbon (GAC/PAC) processes are installed in full-scale drinking water treatment plants (DWTPs) to reduce disinfection byproduct precursors, odor, ammonia, and pesticides. This study investigated the ability of GAC/PAC processes in 23 DWTPs to remove per- and polyfluoroalkyl substances (PFASs). In the GAC process, filter breakthrough of perfluoroalkyl carboxylic acids (PFCAs) occurred faster as the PFCA chain length is decreased. During periods of high water temperatures (20−29 °C), the effluent concentration of two short-chain PFCAs (C4 and C5) surpassed that of the influent after the throughput reached 5,000−7,500 bed volumes (equivalent to 2−3 months) due to desorption. However, such desorption was not observed during periods of low water temperatures (5−19 °C). Meanwhile, long-chain PFCAs were consistently removed, as the GAC was replaced before breakthrough became noticeable. PFAS removal deteriorated at a remarkably fast rate after a partial breakthrough of several tens of percent. Biological activated carbon was proved ineffective in removing PFASs due to its diminished adsorption capacity after long-term use. The PAC process, however, exhibited a slight decrease in PFCA residual (10%) at higher water temperatures (15−30 °C). The PAC dose required for a certain residual ratio was lower with an increase in the hydrophobicity of PFAS; C8-PFCA only required 20 mg/L of PAC for 50% removal, while C4-PFCA required a significantly higher dose of 100−700 mg/L. Consequently, the activated carbon process, which removes organic contaminants in surface water, was inadequate in removing PFASs, particularly those with short chains. Thus, it is recommended that GAC filters be replaced more frequently (within two months) for short-chain PFAS removal. Further, the adsorption performance of PAC must be enhanced.

Assessing coastal outfall impact on shallow enclosed bays water quality: Field and statistical analysis

Shallow bays, valued for their environmental, economic, and social significance, face increasing threats from anthropogenic stressors, primarily wastewater discharge through coastal outfalls. The slow tidal currents in these bays hinder the effective dispersion of pollutants to deeper waters, exacerbating their impact. This study assesses the spatial effects of wastewater and brine discharges on Sulaibikhat Bay's water quality. The approach combines fieldwork, laboratory analysis, and statistical techniques to identify pollutant types, sources, and concentrations near outfalls, nearshore, and offshore areas. Throughout the study, high water temperatures were observed consistently, exceeding 30 °C in summer and 18.6 °C in winter near most outfalls, with a maximum deviation from the ambient water of 11.1 °C recorded in December. In addition to elevated electrical conductivity (EC) levels peaking at 60,700 μs/cm, these elevated temperatures significantly reduce dissolved oxygen levels and have been linked to fish kill events in the Bay. NH3-N, TSS, COD, BOD5, FC, and FS concentrations exceeded allowable limits in 56.4 %, 92.25 %, 40.30 %, 32.1 %, 70 %, and 63.36 % of samples, respectively, often reaching extreme levels. Also, the BOD5/COD ratios suggest the presence of non-biodegradable organic matter, mainly from industrial sewage, and the FC/FS levels implicate human and animal waste. These results indicate a mix of domestic, industrial, and commercial wastewater discharges and underscore the severe threat coastal outfalls pose to ecosystem health and water quality in Sulaibikhat Bay. Principal Component Analysis (PCA) and Cluster Analysis (CA) delineate two distinct environmental zones with varying characteristics and contamination levels, necessitating expanded monitoring. Finally, substantial field research, numerical modeling, and establishing a sustainable environmental management system are needed to protect this fragile ecosystem. Also, converting outfalls into offshore may mitigate the environmental status of the bay by enhancing pollutant dilution and dispersion.

Discharge‐Mediated Temperature Management in a Large, Regulated River, With Implications for Management of Endangered Fish

AbstractFor large, regulated rivers, operators can impact abiotic conditions for the benefit of the ecosystem, primarily by controlling the volume of discharge from upstream reservoirs. Understanding the decision space around discharge is necessary for evaluating tradeoffs between environmental and other objectives. As a result of climate change, warming water temperatures are increasingly becoming a concern for thermally‐sensitive fauna. In California's largest river, the Sacramento, extinction risk of salmon populations is linked to high water temperatures. Yet, little is known about how much water temperature in lower reaches can be affected by reservoir discharge operations, and the potential benefits to salmon. We used a process‐based water temperature model to estimate the ability of reservoir discharge to mediate river temperature heating processes impacting downstream locations (discharge‐mediated temperature management). To bound this analysis, we used historical forcings over a recent 29‐year span. Results indicate reservoir discharge increases of up to 340 cms over the historical record could have decreased water temperature in the lower reaches by up to 3.6°C. Salmon require water below 20°C during most stages of their lifecycle, and we found that normative water operations could ensure 20°C was rarely exceeded for two potential management seasons, in late‐spring and early‐fall. These periods coincide with important rearing and migratory periods for salmon, during which they frequently experience excessive temperatures under the management status‐quo. This analysis provides stakeholders tools to manage conditions for native fauna in the face of a warming climate, and a framework for developing similar tools in other large, regulated rivers.

일회용 종이컵에서 발생하는 나노플라스틱의 생체 내 잔존량 측정

In this study, an experiment was conducted to determine whether nanoplastics extracted from disposable paper cups that are easily accessible and widely used in daily life remain in vivo. In order to extract nanoplastics, water boiled at 95-100℃ was added to a disposable paper cup, and the extracted nanoplastics were observed with a digital microscope. To check whether nanoplastics remained in the body, 1mg/mL of nanoplastic was administered to mice, urine and feces were collected to measure the amount of nanoplastics discharged, and the gastric tissue of mice was collected to confirm the amount of nanoplastics remaining on the stomach. As a result, it was confirmed that a significant amount of nanoplastic in the disposable paper cup was extracted at high water temperature, and the amount of nanoplastic was discharged out of the body, but some remained in the body.

Mass mortality of the Critically Endangered naked characin (Gymnocharacinus bergii): Possible causes and impact

Abstract The naked characin (Gymnocharacinus bergii) is the only endemic fish of the arid Patagonia of Argentina, living only in the thermal headwaters of the Valcheta Stream in the Somuncura Plateau. This species is listed as Critically Endangered on the IUCN Red List. In April 2018, a massive mortality event was observed in the species. Parasitological studies identified the cause as an epidemic of white spot disease, caused by the parasite Ichthyophthirius multifiliis (Ich). Ich is a common disease in aquaculture settings, but it has also been reported as an epizootic in wild fish populations across tropical and temperate regions worldwide. This occurrence is associated with the introduction of fish into non‐native environments. This article presents the first recorded instance of a mass mortality event and Ich outbreak in the naked characin. It includes a mapping of the disease in the headwaters of the stream, an estimation of the impact on the species' population size, and an analysis of potential causes associated with this epidemic. The results indicate that the epizootic produced mortality of 82% of the global population of the naked characin and was linked to the presence and high abundances of the invasive fish species Uruguay tetra (Cheirodon interruptus). The disease occurred in stream sectors where both characid species coexist, particularly in areas with the highest water temperatures. The Ich outbreak represents the most recent and severe threat recorded for the Critically Endangered naked characin. Implementing control measures against the invasive Uruguay tetra is imperative to prevent future outbreaks that could push the species to the brink of extinction in the near future. This study provides crucial information for assessing current management interventions and developing new strategies within the framework of the action plan for naked characin conservation.

Relationship between environmental conditions and biennial growth of kelp Saccharina japonica var. ochotensis, northern Hokkaido, Japan

The kelp Saccharina japonica var. ochotensis occurs in the northern Sea of Japan. A monthly diving survey was conducted at two sampling stations, Tsugaru in Rebun Island and Hourai in Wakkanai district in northern Hokkaido, Japan, from March 2013 to November 2014. Oceanographic conditions, water temperature, nitrate, and irradiance were recorded, and several differences were observed between Tsugaru and Hourai. Higher irradiance at Tsugaru during July and August led to enhanced photosynthesis by sporophytes, and the lower temperature in this area led to increased storage of mannitol from April to September, with more sulfated polysaccharide in sporophytes and greater blade thickness compared to kelp specimens at Hourai. Higher water temperatures in Tsugaru during September and February led to larger sporophytes, whereas lower winter water temperatures in Hourai led to smaller sporophytes. Higher water temperatures from September to February and lower nitrate concentrations throughout the year except in April 2013 and March 2014 in Tsugaru were associated with higher sorus formation rates and lower regeneration (transition from annual to biennial sporophytes) rates than at Hourai. Irradiance at Tsugaru was higher than at Hourai from July to August. Lower temperatures and lower radiation result in a lower rate of sorus formation; whereas higher nitrate concentrations give rise to higher rates of regeneration.

Geochemical Characteristics and Formation Mechanisms of the Geothermal Waters from the Reshui Area, Dulan of Qinghai, China

The Reshui area, located to the northeast of the Qinghai–Tibet Plateau, exhibits complex geological conditions, well-developed structures, and strong hydrothermal activities. The distribution of hot springs within this area is mainly controlled by faults. In this paper, five hot springs from the area were taken as the research object. We comprehensively studied the geochemical characteristics and genetic mechanism of the geothermal water by conducting a field investigation, hydrogeochemistry and environmental isotopic analysis (87Sr/86Sr, δ2H, δ18O, 3H). The surface temperature of the geothermal water ranges from 84 to 91 °C. The geothermal water in the area exhibits a pH value ranging between 8.26 and 8.45, with a total dissolved solids’ (TDS) concentration falling between 2924 and 3140 mg/L, indicating a weakly alkaline saline nature. It falls into the hydrochemical type CI-Na and contains a relatively high content of trace components such as Li, Sr, B, Br, etc., which are of certain developmental value. Ion ratio analysis and strontium isotope characteristics show that the dissolution of evaporite minerals and carbonate minerals serves as a hot spring for the main source of solutes. Hydrogen and oxygen stable isotope characteristics findings indicate that the geothermal water is primarily recharged via atmospheric precipitation. Moreover, the tritium isotopic data suggest that the geothermal water is a mixture of both recent water and ancient water. Moreover, the recharge elevation is estimated to be between 6151 and 6255 m. and the recharge area is located in the Kunlun Mountains around the study area. The mixing ratio of cold water, calculated using the silicon enthalpy equation, is approximately 65% to 70%. Based on the heat storage temperature calculated using the silicon enthalpy equation and the corrected quartz geothermal temperature scale, we infer that the heat storage temperature of geothermal water in the area ranges from 234.4 to 247.8 °C, with a circulation depth between 7385 and 7816 m. The research results are highly valuable in improving the research level concerning the genesis of high-temperature geothermal water in Reshui areas and provide essential theoretical support for the rational development and protection of geothermal resources in the area.

Multi-Element Doping Boosts a Layered Metal Oxide Electrode for Superior Water Oxidation

More than precisely controlling the active species to optimize the binding with reaction intermediates, applying lab-designed electrocatalysts for practical water electrolysis requires overcoming limitations of mass and electron transports, which are however difficult to achieve by a single strategy. Here, based on a category of layered cobalt oxides (ACoO2, A = alkali metal), we report a multi-element doping method to favor the in-situ reconstruction of more-active species during water oxidation, boost the electronic conductivities, and extend the potential range of kinetic currents. Specifically, various doping elements including both cationic and anionic ones were screened experimentally for ACoO2 and the composition of LiCo1-x-y-zNixFeyPdzO2 was identified with the optimal catalytic properties. Compared with common cobalt oxides and (oxy)hydroxides, LiCo1-x-y-zNixFeyPdzO2 regulated the in-situ catalyst reconstruction during both room- and high-temperature water oxidation, and boosted electronic conductivity by 2-4 orders of magnitudes. Consequently, LiCo1-x-y-zNixFeyPdzO2 outperformed RuO2, Co3O4, α- and β-Co(OH)2 by delivering an anion exchange membrane water electrolysis current density of 1 A cm-2 at about 1.75 V, and showed little degradation during the 500-hour stability test. This work represents a step forward in rationally boosting the catalytic properties of anode materials for practical membrane water electrolysis.