Faster Rate Research Articles

Programming the Kinetics of Chemical Communication: Induced Fit vs Conformational Selection.

Life on Earth depends on chemical communication and the ability of biomolecular switches to integrate various chemical signals that trigger their activation or deactivation over time scales ranging from microseconds to days. The ability to similarly program and control the kinetics of artificial switches would greatly assist the design and optimization of future chemical and nanotechnological systems. Two distinct structure-switching mechanisms are typically employed by biomolecular switches: induced fit (IF) and conformational selection (CS). Despite 60 years of experimental and theoretical investigations, the kinetic and evolutive advantages of these two mechanisms remain unclear. Here, we have created a simple modular DNA switch that can operate through both mechanisms and be easily tuned and adapted to characterize its thermodynamic and kinetic parameters. We show that the fastest activation rate of a switch occurs when the ligand is able to bind its inactive conformation (IF). In contrast, we show that when the ligand can only bind the active conformation of the switch (CS), its activation rate can be easily programmed over many orders of magnitude by a simple tuning of its conformational equilibrium. We demonstrate the programming ability of both these mechanisms by designing a drug delivery vessel that can be programmed to release a drug over different time scales (>1000-fold). Overall, these findings provide a programmable strategy to optimize the kinetics of molecular systems and nanomachines while also illustrating how evolution may have taken advantage of IF and CS mechanisms to optimize the kinetics of biomolecular switches.

Coastal Wetlands of Indus River Delta Are Under Risk Due to Reclamation: A Spatiotemporal Analysis During the Past 50 Years From 1972 to 2022

ABSTRACTCoastal wetlands are the most productive and biologically diverse ecosystems, benefiting both human populations and the total environment. However, they are continuously threatened by anthropogenic activities. Indus River Delta is the sixth largest in the world, has been adversely affected due to reclamation. The study examined the spatiotemporal dynamics of coastal wetlands and reclamation in the Indus River Delta from 1972 to 2022. Wetlands conversion to reclamation was extracted from 6‐Landsat images. A land cover transfer matrix was used to analyze land use land cover (LULC) changes in different time intervals. Area‐weight centroid was constructed to determine the migration trend of reclamation and coastal wetlands. Spatial accurateness was assessed using Producer's Accuracy (PA), User Accuracy (UA) and KAPPA coefficient (KC). The results reveal that from 1972 to 2022, the net area of wetlands declined by 1.9% (26.1 km2), while reclamation (settlement and cultivated land) increased by 14.7% (200.1 km2), and 27.5% (373.5 km2), respectively. The fastest areal change rate for coastal wetlands was −1.1 km2/year from 2012 to 2022, whereas the fastest areal change rate for settlement and cultivated land were 7.6 km2/year from 1992 to 2002 and 28.6 km2/year from 2012 to 2022. Centroids of wetlands moved slowly eastwards from Kharo Chan taluka to Keti Bandar in the first and third decades, then southwards in the second decade, later on, westwards in the fourth decade, and finally back southwards from Keti Bandar taluka to the Kharo Chan in the fifth decade with fastest movement. Centroids of settlement expanded in all directions over five decades. Centroids of cultivated land migrated westwards in the first, third and fourth decades, northwards in the second decade and southwards in the fifth decade from Keti Bandar to Kharo Chan. The findings of this study provide a scientific basis for sustainable land development and future planning.

Spatial-Temporal Evolution of Sales Volume of New Energy Vehicles in China and Analysis of Influencing Factors

China’s transportation carbon emissions account for 10% of the total, with nearly 90% originating from road transport. Additionally, China is the world’s largest automotive demand market. Therefore, in the context of achieving the “dual carbon” goals, the promotion and application of new energy vehicles (NEVs) are particularly crucial. However, the current situation regarding the promotion trends and driving mechanisms of NEVs in China remains unclear. Therefore, this study, based on panel data, explores the spatial-temporal evolution of NEV sales in China from 2016 to 2022 through spatial analysis. Simultaneously, based on correlation analysis and geographical detectors, this study qualitatively and quantitatively investigates the driving factors of NEV sales in China. The results show that: (1) China’s NEV sales will increase by 5.7 million units in the seven years from 2016 to 2022, which is an extremely fast growth rate; (2) There are significant spatial-temporal heterogeneities in the sales of NEVs in China. Sales in the eastern region constitute the largest share among the four major economic regions, accounting for 61% by 2022. The northeastern region has the lowest sales, representing only 2.9% of the national total. (3) Among different provinces, the sales in coastal provinces such as Guangdong, ZheJiang, and Jiangsu are much higher than in inland provinces like Tibet and QingHai. (4) The contribution rates of driving factors vary across regions. Overall, however, the order of influence factors is as follows: road length (0.49) > proportion of the tertiary industry (0.48) > road area (0.40). Therefore, infrastructure is identified as the primary influencing factor for the promotion of NEV. This study has revealed the spatial-temporal evolution of NEV sales and their driving mechanisms, aiming to provide theoretical support for the promotion of NEVs in China.

Quantifying the impact of global nitrate aerosol on tropospheric composition fields and its production from lightning NOx

Abstract. Several global modelling studies have explored the effects of lightning-generated nitrogen oxides (LNOx) on gas-phase chemistry and atmospheric radiative transfer, but few have quantified LNOx's impact on aerosol, particularly when nitrate aerosol is included. This study addresses two key questions: (1) how does including nitrate aerosol affect properties such as tropospheric composition, and (2) how do these effects depend on lightning parameterisation and LNOx levels? Using the Met Office's Unified Model–United Kingdom Chemistry and Aerosol (UM–UKCA) global chemistry–climate model, which now includes a modal nitrate aerosol scheme, we investigate these effects with two lightning-flash-rate parameterisations. Our findings show that both nitrate aerosol and LNOx significantly impact tropospheric composition and aerosol responses. Including nitrate aerosol reduces global mean tropospheric OH by 5 %, decreases the tropospheric ozone burden by 4 %–5 %, increases methane lifetime by a similar amount, and alters the top-of-atmosphere (TOA) net downward radiative flux by −0.4 W m−2. The inclusion of nitrate also shifts the aerosol size distribution, particularly in the Aitken and accumulation modes. A 5.2 Tg N yr−1 increase in LNOx from a zero baseline results in global aerosol increases of 2.8 % in NH4, 4.7 % in fine NO3, 12 % in coarse NO3, and 5.8 % in SO4 mass burdens. This much LNOx increase causes relatively small positive changes in aerosol optical depth, TOA radiative flux, and cloud droplet number concentration compared to when nitrate is included. The results, based on a fast uptake rate for HNO3 to produce NH4NO3, likely represent an upper limit on nitrate effects.

Review of: "nanocapacitors, thus emerge as promising fuel sources with astonishingly fast charge release rates. Amazing fast charging"

Review of: "nanocapacitors, thus emerge as promising fuel sources with astonishingly fast charge release rates. Amazing fast charging"

Dynamic Inverse Control of Uncertain Pure Feedback Systems Based on Extended State Observer

A novel, precise disturbance rejection dynamic inversion control algorithm has been proposed. In the high-order dynamic surface control system, an innovative approach utilizes a monotonically increasing inverse hyperbolic sine function to construct an extended state observer, which estimates the uncertain functions at each step. The monotonicity of the inverse hyperbolic sine function simplifies the system stability analysis. Additionally, being a smooth function, it avoids the disturbances caused by piecewise functions at their breakpoints in conventional observer construction, thereby enhancing system stability. The accurate prediction capability of the new observer improves the system’s disturbance rejection performance. To address the inherent differential explosion phenomenon in traditional dynamic inversion control schemes, this paper ingeniously employs a tracking signal observer as a substitute for traditional filters, thus avoiding the differential explosion that may occur with first-order filters. Finally, comparative simulations were conducted to validate the effectiveness of the proposed method. The results show that both the observer and the controller possess high-gain characteristics, and the closed-loop system exhibits a fast convergence rate.

Land cover change and its driving factors in Siberia from 1992 to 2020.

Siberia occupies vast areas underlain by permafrost, and understanding its land cover changes is important for ecological environmental protection in a warming climate. Based on the land cover and climate datasets, we analyzed the land cover changes and their drivers in Siberia from 1992 to 2020. The results show that ① From 1992 to 2020, the areas of evergreen needleleaf trees and deciduous needleleaf trees in Siberia decreased by 9% and 2.5%, and the areas of grassland, shrub, cropland, and construction land increased by 1.5%, 14.2%, 2.8%, and 39.2%, respectively. Cropland expansion had the fastest rate of 1.85% in the continuous permafrost zone, and construction land expansion had the fastest rate of 3.07% in the non-permafrost zone. ② The center of gravity of agricultural land continues to migrate to the northeast, and the center of gravity of construction land continues to migrate to the southwest. ③ The primary drivers for the land cover changes were temperature and precipitation, and active layer thickness also affected grassland, cropland, and deciduous needleleaf trees. The correlation coefficient between active layer thickness and cropland area is 0.74 in the continuous permafrost zone. The interaction between factors is mostly manifested as a two-factor enhancement, with the highest q-value of the interaction of temperature and precipitation for explanatory power. Our results suggest that climate change and permafrost degradation significantly changed land cover in Siberia. This finding deepens our understanding of the mechanisms of land cover change under the influence of permafrost degradation and provides a new perspective on the land cover changes in permafrost regions.

Flow field design and visualization for flow-through type aqueous organic redox flow batteries

Aqueous organic redox flow batteries (AORFBs), which exploit the reversible redox reactions of water-soluble organic electrolytes to store electricity, have emerged as a promising electrochemical energy storage technology. Organic electrolytes possess fast electron-transfer rates that are two or three orders of magnitude faster than those of their inorganic or organometallic counterparts; therefore, their performance at the electrode is limited by mass transport. Direct adoption of conventional cell stacks with flow fields designed for inorganic electrolytes may compromise AORFB performance owing to severe cell polarization. Here, we report the design of a flow field for flow-through type AORFBs based on three-dimensional multiphysics simulation, to realize the uniform distribution of electrolyte flow and flow enhancements within a porous electrode. The electrolyte flow is visualized by operando imaging. Our results show that multistep distributive flow channels at the inlet and point-contact blocks at the outlet are crucial geometrical merits of the flow field, significantly reducing local concentration overpotentials. The prototype pH-neutral TEMPTMA/MV cell at 1.5 M assembled with the optimized flow field exhibits a peak power density of 267.3 mW cm-2. The flow field design enables charging of the cell at current densities up to 300 mA cm-2, which is unachievable with the conventional serpentine flow field, where immediate voltage cutoff of the cell occurs. Our results highlight the importance of AORFB cell stack engineering and provide a method to visualize electrolyte flow, which will be appealing to the field of aqueous flow batteries.

An analysis of the decomposition and driving force of carbon emissions in transport sector in China

China’s transport carbon emissions are increasing quickly and the issue of emission reduction is urgent. This article aims to calculate and decompose China’s transport carbon emissions during 2001–2019. It first calculates the China’s transport carbon emissions by IPCC carbon emission factor method, and then applies the Logarithmic Mean Divisia Index (LMDI) model for decomposition analysis. The conclusion indicates that: (1) Diesel, gasoline, kerosene, and fuel oil are the major energy sources used in China’s transport sector, with the combined consumption of diesel and gasoline exceeding 70%, and the annual growth rate of energy consumption reached 8.92% during 2000–2019. Among them, natural gas and liquefied petroleum gas (LPG) have the fastest growth rate, while the only one showing a downward trend is raw coal, indicating that China’s transportation energy structure is being optimized. (2) Although China’s transport carbon emissions have been increasing, the growth rate has declined since 2013. The proportion of carbon emissions from kerosene, diesel, natural gas, and LPG increased from 2000 to 2019, while that of raw coal, gasoline, and fuel oil decreased. This suggests that the use of clean energy, air transportation, and large-scale transportation is increasing, while the use of heavily polluting fuels and small-scale road transportation is decreasing. (3) Per capita GDP is the driving factor that has the most influence on the increase of China’s transport carbon emissions. Population positively influences transportation carbon emissions too, but issues such as aging, low fertility rates, and insufficient labor force may change the direction of the impact in the next 30 years. (4) The negative effect of energy intensity on transport carbon emissions is the greatest, followed by industrial structure and energy structure. The development of highways, new energy vehicles, railway electrification, multimodal transportation, third-party logistics, and logistics information technology in China has improved the energy structure, reduced energy intensity, and brought China’s transport sector into an important stage of innovation driven and pursuit of coordinated development with the environment.

The first mitogenome of the genus Amphalius (Siphonaptera: Ceratophyllidae) and its phylogenetic implications.

Amphalius spirataenius belongs to Arthropoda, Insecta, Siphonaptera, Ceratophylloidea, Ceratophyllinae, Amphalius. Only 2 species from the subfamily Ceratophyllinae have been sequenced for mitogenomes to date. The genus Amphalius mitogenome research was still blank. The A. spirataenius mitogenome was determined, annotated and analysed for the first time in this study. The 14 825 bp long genome has the typical metazoan of 37 genes with insect ancestral genome arrangement pattern. There was no significant difference in codon usage of 13 protein-coding genes: UUA, UCU, GUU, ACU and GCU were the most frequently used codons. It was found that the reason for codon preference mainly contributed to natural selection base on PR2, ENC-plot and neutrality curve analysis. Evolutionary rate, conserved sites, variable sites and nucleotide diversity analysis indicated that nad6 of A. spirataenius had the fastest evolutionary rate, while cox1 had the slowest evolutionary rate. Phylogenetic trees were reconstructed based on 13 protein-coding genes and 2 rRNA genes datasets using Bayesian inference and maximum likelihood method. The phylogenetic tree supported that both Siphonaptera and Mecoptera were monophyletic, and were sister groups to each other. This study filled gap of the genus Amphalius mitogenome sequences and was of great significance for understanding evolution of the order Siphonaptera.

Conditional Variable Screening for Ultra-High Dimensional Longitudinal Data With Time Interactions.

In recent years, we have been able to gather large amounts of genomic data at a fast rate, creating situations where the number of variables greatly exceeds the number of observations. In these situations, most models that can handle a moderately high dimension will now become computationally infeasible or unstable. Hence, there is a need for a prescreening of variables to reduce the dimension efficiently and accurately to a more moderate scale. There has been much work to develop such screening procedures for independent outcomes. However, much less work has been done for high-dimensional longitudinal data in which the observations can no longer be assumed to be independent. In addition, it is of interest to capture possible interactions between the genomic variable and time in many of these longitudinal studies. In this work, we propose a novel conditional screening procedure that ranks variables according to the likelihood value at the maximum likelihood estimates in a marginal linear mixed model, where the genomic variable and its interaction with time are included in the model. This is to our knowledge the first conditional screening approach for clustered data. We prove that this approach enjoys the sure screening property, and assess the finite sample performance of the method throughsimulations.

Ion-exchange induced multiple effects to promote uranium uptake from nonmarine water by micromotors

As the fundamental resource in nuclear energy, uranium is a sword of two sides, due to its radioactive character that could cause severe impact to the environment and living creatures once released by accident. However, limited by the passive ion transport, the currently available uranium adsorbents still suffer from low adsorption kinetics and capacity. Here, we report a self-driven modular micro-reactor composed of magnetizable ion-exchange resin and adsorbents that can be used to dynamically remove uranium from nonmarine waters. Because of the long-range pH gradient and phoretic flow established by the recyclable ion-exchange resin, the micro-reactor shows a fast uranium adsorption rate and reaches a uranium extraction capacity of 629.3mgg-1 within 10min in 30 ppm uranium solution, as well as good recyclability in repeated use. Numerical simulation result confirms that the phoretic flow and electric field accelerate uranium transport to the adsorbent. Our work provides a new solution for the removal of radioactive uranium with high efficiency.

Tackling water contamination by oncologic drugs: Supported ionic liquids as sustainable adsorbents for cyclophosphamide removal

Due to the increasing incidence of cancer, the consumption of highly toxic oncological drugs is continuously growing. Given the current lack of efficient technologies to remove/treat these toxic drugs in wastewater treatment plants, the environmental quality is compromised, and aquatic organisms are at risk. To address this critical environmental burden, a new strategy based on supported ionic liquids (SILs) for the simultaneous removal of oncologic drugs and toxicity reduction of aqueous samples is here proposed. Silica-based SILs functionalized with imidazolium-based and quaternary ammonium-based ILs were designed and kinetics and isotherm adsorption studies performed. Aiming to develop an adsorbent able to reduce the toxicity of aqueous samples contaminated with oncological drugs, the toxicity reduction was appraised using the model organism Danio rerio. The obtained results disclose that among the studied SILs, the [Si][N3888]Cl (silica functionalized with propyltrioctylammonium chloride) is the best adsorption material (maximum adsorption capacity, qmax = 67.64 mg g−1), with a fast adsorption rate (<20 min). Furthermore, [Si][N3888]Cl was able to remove the toxicity of the treated aqueous samples towards D. rerio embryos, as assessed by lethal and several sublethal endpoints, demonstrating that this material holds remarkable potential for oncological drugs pollution remediation.

Kinetics of hydrothermal reactions of n-butanol over Pt/Al2O3 catalyst for biopropane fuel gas production

Energy defossilisation using drop-in biofuels is an important step towards Net Zero. Producing low-carbon clean-burning propane fuel from biomass provides such additional sustainability benefits. In this work, kinetics of hydrothermal reactions of n-butanol, a biomass-derived feedstock, to produce propane over 5 wt% Pt/Al2O3 catalyst have been studied from 523- 573 K. Experimental data revealed negligible internal and external mass transfer effects and, when fitted to an integral power-rate law equation, gave activation energy of 70 kJ mol−1 (n-butanol reaction order = 1). Furthermore, an appropriate Langmuir-Hinshelwood model was developed, which predicted similar activation energy 62 kJ mol−1. Low adsorption enthalpies for n-butanol (–33.51 kJ mol−1) and water (−18.16 kJ mol−1) indicated weak interactions on the catalyst surface. These agreed with the fast reaction rate of ≈1.0 x 10-5 mol gcat-1 s−1 obtained at ≥ 548 K. As a new research area, generation of such accurate kinetics data will contribute to process development for large-scale biopropane production.

Summertime compound heat extremes change and population heat exposure distribution in China

Amid the cumulative effects of rapid urbanization and climate warming, urban residents face serious health threats posed by heat extremes. Long-term monitoring of extreme high temperatures in cities can provide a foundational framework for mitigating the urban heat environment and enhancing the livability of residents. Utilizing long-term MODIS land surface temperature (LST) data, this study examined the fluctuations of extreme high temperatures, as well as the distribution of urban populations exposed to heat extremes and the associated health risks for urban residents across 289 prefecture-level and above cities in China from 2002 to 2020, considering natural, population and economic regional scales. The results indicated that: (1) Variations in extreme high temperatures. Extreme LST thresholds exhibited an upward trend, with the nighttime growth rate being 0.24°C/decade higher than the day. Regions characterized by higher extreme LST thresholds during the day were concentrated in Northwest and North China, while nighttime were primarily found in South Central and East China. Furthermore, regions showing higher extreme LST thresholds during the day and night were situated in well-developed cities. (2) Changes in cities exposed to heat extremes. Over the past 19 years, the majority of cities have been exposed to compound extreme high temperatures, and the number of such cities increased from 230 to 256. Notably, nearly 42% of cities have been exposed to extreme high temperatures for 15 consecutive years or longer, particularly concentrated in East China and South Central China. Developed cities were more likely to endure persistent heat extremes, especially those with a population of over 5 million and a per capita GDP of over 20,000, which have almost continuously experienced heat extreme exposure for the past 19 years. (3) Urban populations exposed to compound heat extremes. The urban population heat exposure across the country was on the rise, with the fastest growth rate of 2.91 million people per year in the nighttime, and a greater escalation in East and South Central China. Moreover, cities with lower levels of population and economic development represented the primary areas for growth0, while cities with moderate development levels showcased the slowest growth rate. (4) Health risks for urban residents. The number of urban residents dying from cardiovascular and respiratory diseases increased by 522,500, with the elderly and males accounting for a greater proportion of the increase by 234,200 and 149,800, respectively. Additionally, there existed a significant positive correlation between the deaths and heat extremes during the day and night.

Soot particle morphology and polycyclic aromatic hydrocarbons formation molecular dynamics during diffusion combustion of three pentanol biofuels

Soot particles constitute a major pollutant in engine diffusion combustion, posing a serious threat to human health and the atmospheric environment. The employment of carbon-neutral biofuel, pentanol, in engines contributes to reducing soot emissions; however, its effectiveness is contingent upon the position of the OH functional group. This work investigated the soot morphology and microstructural parameters evolution of three pentanol isomers, and explored the influence mechanism of OH functional group positional isomerism on the entire process of PAHs formation at the atomic level. The results showed that the peak of primary particle size and soot volume fraction in pentanol flames showed a trend of 2-pentanol>3-pentanol>1-pentanol, and the initial formation time of soot in 1-pentanol flame is the latest, and the particle aggregate size is the smallest. The entire process of pentanol isomers soot formation can be divided into four stages: fuel pyrolysis forming initial ring, PAHs growing into initial soot, soot chain growth and structural evolution, soot morphology transformation and maturation. Among the three isomers, 2-pentanol has the fastest initial ring formation rate, the highest peak C-number in the largest molecule, and ultimately forms a more mature fullerene-like structure. 1-pentanol has the slowest initial ring formation rate, the lowest peak C-number in the largest molecule, ultimately forms a lower maturity layered structure. In terms of reaction pathways, H-atom abstraction and dehydroxylation reactions jointly dominate the initial decomposition pathway in 1-pentanol combustion, while in 2-pentanol, dehydroxylation becomes the main initial decomposition pathway due to the high stability of H atoms on β‑carbon. The dehydroxylation reaction tends to generate olefins, promoting the generation of C1-C4 hydrocarbon. The oxygen atom bonded on the α‑carbon site exhibits a stronger carbon fixation ability, and C1-C4 hydrocarbons are more inclined to participate in oxidation to form CO rather than promote the soot production.

Numerical study on gas-liquid transport uniformity in full-scale flow field of proton exchange membrane fuel cells

Distribution zone governs airflow transmission and distribution within large-scale flow field, which further affects the discharge of liquid water produced. This paper combines experimental validation and computational fluid dynamics (CFD) methods to elevate mass transfer coherence in full-scale flow field (375 cm2). For the first time, circulation number λ and drainage maldistribution (DM) are introduced to quantify variations in water and gas transport homogeneity attributable to the distribution zone. Effect on orientation and spacing of dot matrix, as well as main field structure are investigated. The results reveal that full-scale flow field inlet and outlet distribution zones manage the behavior of gas and liquid transport. Specifically, dot matrix flow field with an inclination angle α = 90° demonstrates superior flow uniformity, while α = 45° exhibits the fastest initial drainage rate. Optimal comprehensive mass transfer and drainage consistency are achieved with a vertical dot matrix spacing of S = 1.2 mm ∼ 1.5 mm, yielding the lowest maldistribution factor (MF) and DM number of 0.15 and 0.04 respectively. This configuration results in a maximum improvement of 58.4 % and 43.1 %. Notably, a novel aspect is that the drainage rate in full-scale flow field follows an exponential distribution, with peak efficiency factor R = 0.29 observed at α = 90°and S = 1.5 mm.

Regional variation in demographics, reproduction, and body mass growth rates of wild pigs: Implications for population control

AbstractWild pigs are a destructive invasive species throughout many regions of the world and have proven difficult to control or eliminate. Their success as an invasive species is, in part, from their high reproductive potential, which can vary based on available resources, ancestry, and other factors. We opportunistically collected data on demographics (i.e., age and sex), reproduction, and body mass on 2,762 wild pigs throughout various research and operation control activities in Texas, Alabama, Hawai'i, Guam (USA), and Queensland (Australia) during 2016–2024. We evaluated these data for differences among study sites that might lead to a better understanding of wild pig ecology and more effective control of their populations. We found that the age structures of wild pigs varied greatly among sites, with areas with more intense control having younger populations. The timing and frequency of birth pulses also varied by site. Large disparities among populations demonstrated the elasticities of wild pigs in invaded ranges; for example, the Alabama study site had a mostly young population with fast body mass growth rates and 2 discernable birth pulses per year, whereas the Guam study site had an older population with slow body mass growth rates and an indistinguishable birth pulse. We hypothesized that intense population control may increase reproduction rates in younger females through increased body mass growth rates and subsequent reproductive maturity. We recommend that managers identify the seasonal birth pulses of wild pigs in their region, and then intensively focus on removing wild pigs during the 115 days (i.e., gestation period) prior to those birth pulses. This may be counterintuitive to managers that focus on trapping after observing a birth pulse, but it increases the probability of simultaneously removing pregnant females and any associated offspring from previous litters that remained with the pregnant female. We also recommend evaluating regional‐specific intensities of removal that might be required for reducing populations with specific emphasis on whether compensatory reproductive behaviors are generated and how to avoid them.

Cation‐Modified Co‐Based Borophosphates for Efficient and Robust Oxygen Evolution Reaction

AbstractThe development of cost‐effective electrocatalysts for oxygen evolution reaction (OER) is critical and challenging in the field of electrocatalytic water splitting for industrial applications. Herein, a series of cations (Fe, Ni, and Zn)‐doped Co‐based borophosphates with an anion skeleton (Na2CoB3P2O11(OH)·nH2O are prepared by a simple hydrothermal method, in which the cation dopants could be easily achieved via a simple cation exchange during the hydrothermal reaction process. Especially, the Fe dopant increases active sites, improves charge‐mass transfer, and tunes the electronic structures of the Co‐based borophosphate electrode. The optimal Fe‐doped NaCBPO (NaC3FBPO), with the cobalt to iron molar ratio of 3, shows a low overpotential of 289 mV at the current density of 10 mA cm−2, and it can be stable for 16 h at this current density. Above all, it has a fast reaction rate with a low Tafel slope of 84.25 mV·dec−1. This work provides a promising transition metal‐based borophosphates materials with high efficiency and durability toward water splitting.

Fast convergence rates and trajectory convergence of a Tikhonov regularized inertial primal–dual dynamical system with time scaling and vanishing damping

A Tikhonov regularized inertial primal-dual dynamical system with time scaling and vanishing damping is proposed for solving a linearly constrained convex optimization problem in Hilbert spaces. The system under consideration consists of two coupled second order differential equations and its convergence properties depend upon the decaying speed of the product of the time scaling parameter and the Tikhonov regularization parameter (named the rescaled regularization parameter) to zero. When the rescaled regularization parameter converges slowly to zero, the generated primal trajectory converges strongly to the minimal norm solution of the problem under suitable conditions. When the rescaled regularization parameter converges rapidly to zero, the system enjoys fast convergence rates in the primal–dual gap, the feasibility violation, the objective residual, and the gradient norm of the objective function along the trajectory, and the weak convergence of the trajectory to a primal–dual solution of the linearly constrained convex optimization problem. Finally, numerical experiments are performed to illustrate the theoretical findings.