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The excellent electrocatalytic performance of the LCO-NiFe-C 3 N 4 was attributed to the exposure of the true active site after adulteration. [Display omitted] • Design a stable 3D conductive network with uniform nanosphere distribution. • Excellent performance results from true active site exposure after adulteration. • DFT calculations proved the source of catalytic activity. The rising global energy demand & environmental crisis spur exploration of traditional fuel alternatives. Hydrogen, with high energy density & pollution-free potential, is seen as a promising energy carrier. The development of efficient and durable electrocatalysts for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is of paramount importance for renewable energy conversion and storage systems. Developing efficient and stable catalysts is crucial for improving OER performance, but the scarcity, high cost, and stability issues of precious metal oxide catalysts hinder their industrial application. Herein, the composite material was synthesized using a combination of sol–gel and one-step hydrothermal methods, followed by an annealing process. The inherent electrocatalytic activity of LaCoO 3 , a perovskite oxide, towards both OER and HER was harnessed. In an alkaline electrolyte, the LCO-NiFe-C 3 N 4 demonstrated remarkable electrocatalytic performance with overpotentials of 251.4 mV for OER and 186.7 mV for HER at a current density of 10 mA cm-2. The Tafel slopes were 60.8 mV dec-1 for OER and 138.53 mV dec-1 for HER, suggesting that the LCO-NiFe-C 3 N 4 composite material is a promising candidate as a bifunctional catalyst. Theoretical calculations also confirm that doped elements can effectively regulate the electronic properties of active sites, thereby reducing the energy barrier of the rate-limiting step in the OER reaction and significantly enhancing the electrocatalytic activity of the catalyst. This study presents the synthesis and electrocatalytic performance evaluation of a novel (LCoO 3 -NiFe-C 3 N 4) LCO-NiFe-C 3 N 4 composite material, showcasing its potential as an effective bifunctional catalyst. [ABSTRACT FROM AUTHOR]

The commercialization and scalability of proton exchange membrane (PEM) fuel cells have been hindered by the sluggish kinetics of the oxygen reduction reaction (ORR) and the high cost of platinum electrocatalysts. Heteroatom-doped graphene has emerged as a promising alternative catalyst due to the synergistic effects of the dopants on the graphene structure. This study aims to synthesize boron, nitrogen, and sulfur tri-doped reduced graphene oxide (BNS-rGO) to elucidate the role of dopants in enhancing the electrocatalytic activity of doped graphene. In this study, B-, N-, and S-tri-doped graphene was synthesized via a one-pot hydrothermal reaction of graphene oxide (GO) with boric acid and thiourea. A comprehensive characterization of the synthesized materials was conducted using various analytical techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), ultraviolet–visible spectroscopy (UV–vis), scanning electron microscopy (SEM), and cyclic voltammetry. These analyses confirm the successful incorporation of B, N, and S dopants into the graphene structure. The tri-doped BNS-rGO catalyst exhibited superior ORR activity and a higher current density. This enhanced performance can be attributed to the reduced number of oxygen-containing functional groups, increased surface area, and improved electrical conductivity of the doped graphene structure. This study demonstrated the potential of metal-free heteroatom-doped graphene structures for the development of cost-effective and stable ORR electrocatalysts for PEM fuel cells and other energy applications. The successful synthesis and characterization of BNS-rGO provide valuable insights into the role of dopants in enhancing the electrocatalytic activity of graphene-based materials. [ABSTRACT FROM AUTHOR]

The low theoretical capacity and conductivity of Li4Ti5O12 (LTO) impose limitations on its capacity release at high rate, so a core–shell structure, LSbC-10 [87 wt.% Li4Ti5O12 + 10 wt.% Sb2O3 + 3 wt.% carbon nanotubes (CNTs)] with Sb3+-doped and CNT-wrapping has been synthesized by liquid-phase dispersion and hydrothermal crystallization to address this problem. The obtained results demonstrated the successful preparation of LSbC-10 with exceptional properties. The LSbC-10 exhibits enhanced crystallinity and an increased Ti3+/Ti4+ ratio, which promotes the material's conductivity, while the polarization resistance decreased significantly. Building upon the LTO, the rate capability (5C/1C) has been boosted to 83.41%, while the reversible capacity retention rate (0.1C(re)/0.1C) has increased to 93.27%. The Li+ diffusion coefficient also doubled to achieve a value of 1.5316 × 10−9 cm2 s−1. After undergoing fast charge–discharge at a rate of 5C for 1000 cycles, the capacity reached 228.53 mAh g−1, representing a remarkable increase of 43.05% compared to the LTO (159.75 mAh g−1). Compared with the recently reported Li4Ti5O12 composites, the rate capability still had obvious advantages. In the meantime, straightforward and green processes can reduce the pressure on the environment during industrial production. The outstanding performance exhibited by LSbC-10 not only demonstrates that Sb3+-doped and CNT-wrapping significantly enhances the market competitiveness of Li4Ti5O12 but also provides a new model for the study of insertion anode electrode composite conversion/alloying anode electrode besides single doping or coating. [ABSTRACT FROM AUTHOR]

The electrochemical detection of p-nitrophenol (PNP) has gained significant attention due to its potential application in environmental monitoring and food safety. In this study, a novel electrochemical sensor based on a (CeGdHfPrZr)O 2 (HEO) nanoparticle-modified glassy carbon electrode (GCE) has been developed for the detection of PNP. Hydrothermal synthesis was employed to prepare a single-phase HEO nanoparticle. Various characterization techniques were employed to investigate the prepared HEO nanoparticles. The GCE was modified with HEO nanoparticles to enhance its electrocatalytic activity for the detection of PNP. As a result, the oxidation peak current of PNP was greatly enhanced compared to unmodified GCE, indicating an improved electrode reaction kinetics. The sensor showed high sensitivity (0.1517 μA μM−1 cm−2) and selectivity towards PNP, with a detection limit as low as 0.321 μM. The developed electrochemical sensor exhibited excellent reproducibility and selectivity towards PNP over other interfering species. The reusability and stability of the sensor were also investigated. The modified GCE exhibited good long-term stability and could be reused for at least 50 cycles without significant loss of sensitivity. • A high-entropy oxide nanoparticle based electrochemical sensor is proposed. • The modified electrode detects nitrophenol at sub-micromolar concentrations. • Modified electrode effectively employed in tap water samples to monitor p-nitrophenol. • Minimal interference by other ions during p-nitrophenol sensing is observed. [ABSTRACT FROM AUTHOR]

Bone tissue engineering aims to develop biomaterials that are capable of effectively repairing and regenerating damaged bone tissue. Among the various polymers used in this field, polycaprolactone (PCL) is one of the most widely utilized. As a biocompatible polymer, PCL is easy to fabricate, cost-effective, and offers consistent quality control, making it a popular choice for biomedical applications. However, PCL lacks inherent antibacterial properties, making it susceptible to bacterial adhesion and biofilm formation, which can lead to implant failure. To address this issue, this study aims to enhance the antibacterial properties of PCL by incorporating calcium phosphate composite (PCL_CaP) nanostructures onto its surface via hydrothermal synthesis. The resulting "PCL_CaP" nanostructured surfaces exhibited improved wettability and demonstrated mechano-bactericidal potential against Escherichia coli and Bacillus subtilis. The flake-like morphology of the fabricated CaP nanostructures effectively disrupted bacteria membranes, inhibiting bacterial growth. Furthermore, the "PCL_CaP" surfaces supported the adhesion, proliferation, and differentiation of pre-osteoblasts, indicating their potential for bone tissue engineering applications. This study demonstrates the promise of calcium phosphate composite nanostructures as an effective antibacterial coating for implants and medical devices, with further research required to evaluate their long-term stability and in vivo performance. [ABSTRACT FROM AUTHOR]

Infections continue to pose significant challenges in dentistry, necessitating the development of innovative solutions that can effectively address these issues. This study focuses on creating coatings made from polymethyl methacrylate (PMMA) enriched with zinc oxide–silver composite nanoparticles, layered to Ti6Al4V–titanium alloy substrates. The application of these materials aims to create a solution for the abutments utilized in complete dental implant systems, representing the area most susceptible to bacterial infections. The nanoparticles were synthesized using a hydrothermal method, optimized through specific temperature and pressure parameters to achieve effective morphologies and sizes that enhance antibacterial efficacy. The layers were applied to the titanium substrate using the spin coating technique, chosen for its advantages and compatibility with the materials involved. Comprehensive analyses were conducted on the antimicrobial powders, including X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Furthermore, the PMMA-based coatings incorporating antimicrobial nanoparticles were evaluated to ensure uniformity and homogeneity across the titanium alloy surface by IR mapping and SBF immersion–SEM analysis. The antimicrobial activity of the samples was demonstrated with impressive results against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans, as assessed through biofilm modulation studies. The biocompatibility of the samples was validated through in vitro cell-based assays, which demonstrated excellent compatibility between PMMA-based coatings and human preosteoblasts, confirming their potential suitability for future use in dental implants. [ABSTRACT FROM AUTHOR]

[Display omitted] • The S=O bond formed via hydrothermal method tightly binds oxygen-rich vacancy WO 3 with N -doped Zn 0.6 Cd 0.4 S. • Oxygen vacancies introduced into WO 3 serve as bridging sites, facilitating a closer interaction with N -doped Zn 0.6 Cd 0.4 S. • An efficient Z-scheme charge transfer mechanism was formed in the composites. • An excellent hydrogen evolution activity of 21.98 mmol·g−1 was obtained under visible light irradiation. Photocatalytic water splitting technology for H 2 production represents a promising and sustainable approach to clean energy generation. In this study, a high concentration of oxygen vacancies was introduced into tungsten trioxide (WO 3) to create a vacancy-rich layer. This modified WO 3 (WO 3-x) was then combined with N -doped Zn 0.6 Cd 0.4 S through a hydrothermal synthesis, resulting in the formation of a Z-scheme heterojunction composite aimed at enhancing photocatalytic performance. Under visible light, the H 2 production activity of the composite reached an impressive 8.52 mmol·g−1 without adding co-catalyst Pt. This corresponds to enhancements of 7.82 and 4.39 times the production yield of pure ZCS and ZCSN, respectively. However, the hydrogen production increased to 21.98 mmol·g−1 when Pt was added as a co-catalyst. Furthermore, an array of characterizations were employed to elucidate the presence of oxygen vacancies and the establishment of the Z-scheme heterojunction. This structural enhancement significantly facilitates the utilization of photo-generated electrons while effectively preventing photo-corrosion of ZCSN, thus improving material stability. Our study provides a new scheme for the incorporation of oxygen-rich vacancy and the construction of Z-scheme heterojunction, demonstrating a synergistic effect that greatly advances photocatalytic performance. [ABSTRACT FROM AUTHOR]

Perovskite oxide has good sensitivity to VOCs gases, but its gas-sensitive properties are negatively affected by high humidity, thereby limiting its potential application in respiratory gas detection. This study focuses on synthesizing porous LaFeO3 of perovskite type used a dual-process method involved hydrothermal synthesis with thermal treatment. The morphology and evolution of porous LaFeO3 microspheres was studied. The LaFeO3 sensors exhibited p-type gas-sensitive behavior with notable selectivity for respiratory gases. The LaFeO3 sensor represented a significant response value of 9.7 to a 100 ppm C2H5OH concentration, with a rapid response/recovery time of 8 s/9 s at 300 °C. The sensor demonstrated a high response (S = 4.2) and a low detection limit of 100 ppb at 90% relative humidity. The superior sensor performance was due to the porous surface structure of LaFeO3 microspheres, which improved the gas diffusion channels and reaction sites with microspheres. The density of states map revealed a strong orbital hybridization between C2H5OH and LaFeO3, resulted in a calculated adsorption energy of − 1.18 eV, signified a strong adsorption affinity in line with the experimental results. [ABSTRACT FROM AUTHOR]

An intricately designed one-pot hydrothermal approach was utilized to synthesize yolk-shelled Co 3 Fe 1 glycerate, demonstrating its role as a highly efficient electrocatalyst for the oxygen evolution reaction. [Display omitted] • A convenient method to synthesize a range of CoFe gly with controllable surface morphologies. • The yolk-shell structure of Co 3 Fe 1 gly ensures uniformly distributed active sites, promoting efficient mass transfer. • Co 3 Fe 1 gly shows great potential for advancing electrode material development. CoFe-based catalysts are efficient electrocatalysts for the oxygen evolution reaction (OER) in alkaline media. Here, we present a simple one-pot hydrothermal method for synthesizing a series of CoFe glycerates with controllable surface morphologies and investigate their potential as highly efficient catalysts for the OER in alkaline media. These CoFe glycerates exhibit a unique yolk-shell microsphere structure assembled from ultrathin nanosheets. The adjustment of the surface nanosheet size is achieved by varying the CoFe ratio, ensuring a more efficient electrocatalytic system for the OER process. Due to the abundant active sites provided by the yolk-shell structure and interleaved ultrathin nanosheets, Co 3 Fe 1 glycerate (Co 3 Fe 1 gly) demonstrates a low overpotential (283 mV) and a small Tafel slope (44.61 mV dec−1) at 10 mA cm−2. Additionally, Co 3 Fe 1 gly exhibits excellent durability in alkaline electrolytes. Moreover, a series of characterizations demonstrate that the active sites of Co 3 Fe 1 gly are the high-valence Co species generated during the OER process. This study opens a promising avenue for utilizing efficient and low-cost electrocatalysts to enhance OER performance. [ABSTRACT FROM AUTHOR]

A novel mineral-like phosphate hydrate Na6.9Ni2+0.9V3+4.3Al0.8(PO4)8(H2O)2 (Z = 2) was obtained under high-temperature hydrothermal conditions by modeling the chemistry of geothermal brines in natural geological solutions. The compound, characterized by scanning electron microscopy and microprobe analysis, possesses an orthorhombic symmetry with the Cccm space group; the unit cell parameters are a = 6.4082(8), b = 19.6813(19), c = 10.5035(11) Å. Here we report its crystal structure studied by low-temperature single crystal X-ray diffraction and discussed as derived from the α-CrPO4 archetype, known for a large range of compounds with promising properties. Three-dimensional continuous migration pathways for Na+ within the structure were found and confirmed by a bond valence energy landscape analysis. The migration barriers turned out to be ~0.44 eV along the a and b directions and ~0.42 eV along the c axis. These values suggest that the compound may be a potential electrode material for sodium-ion batteries. [ABSTRACT FROM AUTHOR]

COx-free H2, along with uniform carbon nanotubes, can be achieved together in high yield by CH4 decomposition. It only needs a proper catalyst and reaction condition. Herein, Fe-based catalyst dispersed over titania-incorporated-alumina (Fe/Ti-Al), with the promotional addition of lanthanides, like CeO2 and La2O3, over it, is investigated for a methane decomposition reaction at 800 °C with GHSV 6 L/(g·h) in a fixed-bed reactor. The catalysts are characterized by temperature-programmed reduction (TPR), powder X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy (TEM). The promoted catalysts are facilitated with higher surface area and enhanced dispersion and concentration of active sites, resulting in higher H2 and carbon yields than unpromoted catalysts. Ceria-promoted 20Fe/Ti-Al catalyst had the highest concentration of active sites and always attained the highest activity in the initial hours. The 20Fe-2.5Ce/Ti-Al catalyst attains >90% CH4 conversion, >80% H2-yield, and 92% carbon yield up to 480 min time on stream. The carbon nanotube over this catalyst is highly uniform, consistent, and has the highest degree of crystallinity. The supremacy of ceria-promoted catalyst attained >90% CH4 conversion even after the second cycle of regeneration studies (against 87% in lanthanum-promoted catalyst), up to 240 min time on stream. This study plots the path of achieving catalytic and carbon excellence over Fe-based catalysts through CH4 decomposition. [ABSTRACT FROM AUTHOR]

[Display omitted] • A unique carbon coating Ge nanospheres with a cubic hollow structure (Ge@C) is controllably designed and synthesized by using low-cost GeO 2 as precursor. • The hollow Ge@C nanostructure not only provides abundant internal space to alleviate volumetric expansion of Ge, but also facilitates the transmission of Li+ and electrons. • The hollow Ge@C shows very superior lithium storage performance with enhanced Li+ adsorption ability and low Li+ diffusion energy barrier. • This work is a very important breakthrough for the development of high-performance Ge based anode for lithium ion batteries. Germanium based nanomaterials are very promising as the anodes for the lithium ion batteries since their large specific capacity, excellent lithium diffusivity and high conductivity. However, their controllable preparation is still very difficult to achieve. Herein, we facilely prepare a unique carbon coating Ge nanospheres with a cubic hollow structure (Ge@C) via a hydrothermal synthesis and subsequent pyrolysis using low-cost GeO 2 as precursors. The hollow Ge@C nanostructure not only provides abundant interior space to alleviate the huge volumetric expansion of Ge upon lithiation, but also facilitates the transmission of lithium ions and electrons. Moreover, experiment analyses and density functional theory (DFT) calculations unveil the excellent lithium adsorption ability, high exchange current density, low activation energy for lithium diffusion of the hollow Ge@C electrode, thus exhibiting significant lithium storage advantages with a large charge capacity (1483 mAh/g under 200 mA g−1), distinguished rate ability (710 mAh/g under 8000 mA g−1) as well as long-term cycling stability (1130 mAh/g after 900 cycles under 1000 mA g−1). Therefore, this work offers new paths for controllable synthesis and fabrication of high-performance Ge based lithium storage nanomaterials. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hierarchical core-shelled CoMo-LDH@CuCo 2 S 4 NWAs/NF is prepared by hydrothermal synthesis and electrodeposition. • The electrode exhibits a high specific capacity of 1265.9 C g−1 at 1 A g−1. • The electrode shows a 92.2% capacity retention ratio at 10 A g−1 after 10, 000 cycles. • The energy density of the assembled HSC device is 52.2 Wh kg−1 at the power density of 983.9 W kg−1. The development of core-shelled heterostructures with the unique morphology can improve the electrochemical properties of hybrid supercapacitors (HSC). Here, CuCo 2 S 4 nanowire arrays (NWAs) are vertically grown on nickel foam (NF) utilizing hydrothermal synthesis. Then, CoMo-LDH nanosheets are uniformly deposited on the CuCo 2 S 4 NWAs by electrodeposition to obtain the CoMo-LDH@CuCo 2 S 4 NWAs/NF electrode. Due to the superior conductivity of CuCo 2 S 4 (core) and good redox activity of CoMo-LDH (shell), the electrode shows excellent electrochemical properties. The electrode's specific capacity is 1271.4 C g−1 at 1 A g−1, and after 10, 000 cycles, its capacity retention ratio is 92.2 % at 10 A g−1. At a power density of 983.9 W kg−1, the CoMo-LDH@CuCo 2 S 4 NWAs/NF//AC/NF device has an energy density of 52.2 Wh kg−1. This indicates that CoMo-LDH@CuCo 2 S 4 /NF has a great potential for supercapacitors. [ABSTRACT FROM AUTHOR]

A conceptually new approach is developed for hydrothermal synthesis of nanostructured iron oxides for energy storage in anodes of supercapacitors. The use of biocompatible organic additives facilitates the fabrication of electrodes with enhanced capacitance. The use of amino acids, such as L-histidine (HS), L-lysine (LS) and L-arginine (AR), as capping agents results in the crystallization of antiferromagnetic α-Fe2O3 phases, which show higher capacitance than that of α-Fe2O3 formed without additives using NaOH for pH modification. Surprisingly, the use of meglumine (ML) as an alkalizer–capping agent instead of NaOH results in the fabrication of a ferrimagnetic γ-Fe2O3 phase. The γ-Fe2O3 electrodes prepared using ML show a capacitance of 2.97 F cm−2 from cyclic voltammetry data at 2 mV s−1 and 3.22 F cm−2 from galvanostatic charge–discharge data at 3 mA cm−2 in a potential window of −0.8–0 V in 0.5 M Na2SO4 electrolyte. The high active mass γ-Fe2O3 electrodes, prepared using ML show higher capacitance and lower resistance, compared to the α-Fe2O3 electrodes, prepared using HS, LS and AR. Moreover, the γ-Fe2O3 electrodes prepared using ML exhibit higher capacitance, compared to the literature data for γ-Fe2O3 electrodes, prepared by other methods. The particle size, magnetization and capacitance of the γ-Fe2O3 electrodes can be varied by the variation in synthesis temperature. The obtained γ-Fe2O3 is a promising magnetically ordered pseudocapacitive material for energy storage and other applications based on magnetocapacitive properties. The synthesis method developed in this investigation can be used for the fabrication of other functional nanomaterials. [ABSTRACT FROM AUTHOR]

This study investigates the magnetic and dielectric properties of cobalt–zirconium co-doped iron oxide nanoparticles synthesized via the hydrothermal method. The synthesis was conducted at 150 °C, with reaction times of 4, 6, 8, 10, and 12 h. Co-doping with cobalt and zirconium significantly influenced the magnetic phase formation of iron oxide. Magnetic properties were characterized using a Vibrating Sample Magnetometer (VSM), revealing ferromagnetic behavior with a maximum saturation magnetization of 45 emu/g for the 8 h sample. The dielectric properties were analyzed through impedance spectroscopy across a wide frequency range, and the results were interpreted using Maxwell–Wagner's model and Koop's theory. The dielectric constant reached its maximum value of approximately 58 at a logarithmic frequency of 1.5 Hz for the sample synthesized for 8 h. This study highlights the importance of synthesis time in optimizing both the magnetic and dielectric properties of (Co, Zr) co-doped iron oxide nanoparticles. [ABSTRACT FROM AUTHOR]

In this study, the potential to modify the phase structure and morphology of manganese dioxide synthesized via the hydrothermal route was explored. A series of samples were prepared at different synthesis temperatures (100, 120, 140, and 160 °C) using KMnO4 and MnSO4·H2O as precursors. The phase composition and morphology of the materials were analyzed using various physicochemical methods. The results showed that, at the lowest synthesis temperature (100 °C), an intercalation compound with composition K1.39Mn3O6 and a very small amount of α-MnO2 was formed. At higher temperatures (120–160 °C), the amount of α-MnO2 increased, indicating the formation of two clearly distinguished crystal structures. The sample obtained at 160 °C exhibited the highest specific surface area (approximately 157 m2/g). These two-phase (α-MnO2/K1.39Mn3O6) materials, synthesized at the lowest and highest temperatures, respectively, and containing an appropriate amount of carbon xerogel, were tested as active mass for positive electrodes in a solid-state supercapacitor, using a Na+-form Aquivion® membrane as the polymer electrolyte. The electrochemical evaluation showed that the composite with the higher specific surface area, containing 75% manganese dioxide, demonstrated improved characteristics, including 96% capacitance retention after 5000 charge/discharge cycles and high energy efficiency (approximately 99%). These properties highlight its potential for application in solid-state supercapacitors. [ABSTRACT FROM AUTHOR]

This paper presents the laboratory study results of the hydrothermal synthesis of compounds structurally related to the jarosite group, which is characterized by basic iron sulfate AFe3(SO4)2(OH)6 as the main structural component containing A+ cations such as K+, Ag+, and NH4+. The synthesis process involves preparing the initial model solution using soluble salts of the studied metals, either jointly or individually. The resulting solution is then processed in a sealed vessel (autoclave) at a temperature exceeding 100 °C. This study was conducted within a temperature range of 105–200 °C, with experiment durations varying and a maximum dwell time of 300 min. The zero-time value was defined as the moment the autoclave reached the required temperature. It was observed that adding potassium salts to the solution during hydrothermal synthesis reduced the amount of silver precipitated as argentojarosite. An increase in process temperature from 105 °C to 200 °C resulted in a rise in silver precipitation, from 35% to 69%. The equilibrium constants of the reactions involved in the precipitation of specific jarosite group compounds were calculated, and the reaction order was determined. [ABSTRACT FROM AUTHOR]

A cost-effective industrial TiOSO4 solution was employed to fabricate visible light active sulfur-doped titanium dioxide (S-TiO2) via a facile hydrothermal method. The effect of calcination temperature on morphology, particle size, crystallinity, and photocatalytic property of S-TiO2 was systematically investigated. Successful incorporation of sulfur into TiO2 was confirmed by carbon-sulfur analysis, X-ray photoelectron spectroscopy (XPS), and Energy dispersive spectrometer (EDS). The research results demonstrated that calcination temperature significantly impacted the crystallinity, specific surface area, sulfur content, and light absorption properties of S-TiO2. The catalyst calcined at 400 °C revealed the highest photocatalytic activity, with a rate constant of 0.02408 min−1, approximately 25 times higher than commercial P25 catalyst. The higher activity was attributed to the synergistic effect of well-crystallized anatase phase, specific surface area, and red shift of spectral absorption. [ABSTRACT FROM AUTHOR]

Zinc ion batteries (ZIBs) are increasingly prominent due to their cost-effectiveness, abundance, environmental safety, mature processing methods, high volumetric energy density, and compatibility with aqueous electrolytes. However, a significant challenge lies in finding a suitable cathode material with high capacity and structural stability. Manganese dioxide (MnO 2) is a promising candidate for ZIB cathodes in aqueous systems, surpassing other metal oxides in potential. However, MnO 2 cathodes encounter challenges, including rapid capacity degradation and limited cyclic stability. Enhancing the structural stability of host materials during intercalation presents a significant avenue for increasing cathode capacity. In this study, we employed a hydrothermal method to synthesize MnO 2 , followed by annealing in an argon atmosphere at 300 °C for 4 h for MnO 2 -300 and 400 °C for 2 h for MnO 2 -400 to bolster its structural integrity. The properties of annealed samples MnO 2 -300 and MnO 2 -400 are compared with pristine samples (MnO 2 -P). Initially, XRD analysis is conducted to compare their structures, followed by a comparison of electrochemical properties, including Cyclic Voltammetry (CV) and charge-discharge analysis. MnO 2 -400 exhibits a higher initial capacity (149.3 mAhg−1 at 0.1 Ag-1) than MnO 2 -300 (129.0 mAhg−1 at 0.1 Ag-1) and MnO 2 -P (107.9 mAhg−1 at 0.1 Ag-1). An extended cycling test of up to 500 cycles also indicates that annealing MnO 2 in an Ar atmosphere enhances structural stability and capacity compared to the unannealed sample. [ABSTRACT FROM AUTHOR]