Materials In Aqueous Environments Research Articles

Evaluation of influence of dissolved oxygen on corrosion behaviors of FeCrW model alloys in 360 °C water

The dissolved oxygen in a coolant can affect the oxidation properties of structural materials. A desirable oxide phase formation is achieved by manipulating the oxygen level in the coolant, which can mitigate structural material degradation in nuclear power plants. Therefore, the role of dissolved oxygen in the corrosion of structural materials in aqueous environments needs to be understood. In this study, a short-term corrosion test (up to 300 h) of Ferritic/Martensitic steels (F/M steels; FeCrW model alloys), namely, Fe12Cr1W, Fe9Cr1W, and Fe9Cr, in stagnant water at 360 °C was performed in a pressurized autoclave with the dissolved oxygen concentration controlled to 1 ppm or a very low level (<1 ppm). The results of the corrosion tests showed that an increase in the oxygen level in the water elevated the corrosion potential, allowing the phase transition of iron oxide from magnetite (Fe3O4) to hematite (Fe2O3), whereas there was no significant correlation between the concentrations of the alloying elements Cr and W and the oxide growth rate. In addition, hematite was found to mitigate further oxide growth. Finally, a mechanism for the growth of the initial oxide layer was proposed based on the experimental results.

On the Degradation of Vanadium-Based Phosphate Framework Electrode Materials in Aqueous Environments

Na3V2(PO4)3 and Na3V2(PO4)2F3 are among the most studied and applied positive electrode materials in non-aqueous sodium-ion batteries due to their relatively high capacities and redox potentials. However, the stability of these materials in aqueous environments is relatively low limiting their applications in aqueous batteries or deionization cells. In this study, we provide a comprehensive analysis of Na3V2(PO4)3 and Na3V2(PO4)2F3 degradation in aqueous media using a number of techniques such as standard electrochemical methods, elemental analysis, powder X-ray diffractometry, and rotating ring-disc electrode. The latter allows for real time in situ/operando degradation analysis during electrochemical operation. The results show that Na3V2(PO4)3 suffers from chemical vanadium dissolution when immersed even in neutral pH electrolytes, whereas Na3V2(PO4)2F3 is significantly more stable. The results obtained by the rotating ring-disc electrode technique explicitly show that at pH ∼7 Na3V2(PO4)3 and Na3V2(PO4)2F3 generate most of the soluble V(V) species during the electrochemical charging process. Whereas in acidic pH, there is also additional electrochemically-induced generation of soluble V(IV) species during the discharging process. The overall results suggest that fluoride ions significantly increase the structural stability of phosphate materials in aqueous environments. Potentially, a careful electrolyte design with controlled proton and water activity could enable the use of Na3V2(PO4)2F3 in aqueous electrochemical devices.

Harnessing the radical potential of calcium-activated biochar for non-peroxide catalytic degradation of bisphenol S

Biochar, characterized by its rich surface functional groups, defective structure, and inherent aromaticity, serves as a promising catalyst in Advanced Oxidation Processes (AOPs). The generation of Reactive Oxygen Species (ROS) stems from the heterolytic cleavage of peroxides, facilitated by electron transfer from biochar's functional groups. However, safety hazards of peroxides during transportation and storage persist. This study explores a non-peroxide-based oxidation mechanism via Calcium Chloride-activated biochar (CaBC). Remarkably, upon aeration, Bisphenol S (BPS) concentration in water decreased by 25.7 % after reaching adsorption saturation. Reactive Oxygen Species (ROS) generation was confirmed by electron paramagnetic resonance, with species including •OH, •O2–, •CH3, •CH2OH, and CH3C(=O)OO•. Degradation products of BPS were identified using Liquid Chromatography-Mass Spectrometry (LC-MS), their biosafety was assessed, and the degradation pathways of BPS were analyzed through density functional theory (DFT) calculations. This study highlights the potential of biochar in safer, mild catalytic oxidation processes and offers insights into the radical reactions of carbon-based materials in aqueous environments.

Full-Color Long-Lived Room Temperature Phosphorescence in Aqueous Environment.

Long-lived room temperature phosphorescence (RTP) materials are widely utilized in the field of biological and chemical sensing, due to their unique characteristics of long-lived luminescence and no background autofluorescence. However, the realization of full-color RTP in aqueous solution still remains a great challenge. Herein, a feasible strategy for achieving high stability and full-color RTP of carbon dots (CDs)-based composite materials in aqueous environment is reported by constructing a rigid hydrogen bonds' network. The obtained m,p-CDs@CA composite materials exhibit deep-blue RTP with phosphorescence quantum yield of 23.2% and lifetime of 1.74 s, and the afterglow can last for over 12 s. More importantly, the m,p-CDs@CA composite materials are desirable in the detection of biomarkers, because of excellent stability, dispersion, and long-lived RTP properties. The m,p-CDs@CA suspension also displays excellent sensitivity, and a limitation of detection as low as 5.61 and 550nm for biomarkers 5-hydroxyindole-3-acetic acid (HIAA) and serotonin (5-hydroxytryptamine, HT), respectively. Meanwhile, the sensing performance exhibits excellent selectivity even in the presence of other competitive species in blood plasma and urine. With superior selectivity, the long-lived phosphorescence probe based on m,p-CDs@CA suspension can be as an effective biomarker for carcinoid identification, which has potential application in clinical analysis.

A Highly Efficient Phosphorescence/Fluorescence Supramolecular Switch Based on a Bromoisoquinoline Cascaded Assembly in Aqueous Solution.

Despite ongoing research into photocontrolled supramolecular switches, reversible photoswitching between room‐temperature phosphorescence (RTP) and delayed fluorescence is rare in the aqueous phase. Herein, an efficient RTP‐fluorescence switch based on a cascaded supramolecular assembly is reported, which is constructed using a 6‐bromoisoquinoline derivative (G3), cucurbit[7]uril (CB[7]), sulfonatocalix[4]arene (SC4A4), and a photochromic spiropyran (SP) derivative. Benefiting from the confinement effect of CB[7], initial complexation with CB[7] arouses an emerging RTP signal at 540 nm for G3. This structure subsequently coassembles with amphiphilic SC4A4 to form tight spherical nanoparticles, thereby further facilitating RTP emission (≈12 times) in addition to a prolonged lifetime (i.e., 1.80 ms c.f., 50.1 µs). Interestingly, following cascaded assembly with a photocontrolled energy acceptor (i.e., SP), the efficient light‐driven RTP energy transfer occurs when SP is transformed to its fluorescent merocyanine (MC) state. Ultimately, this endows the final system with an excellent RTP–fluorescence photoswitching property accompanied by multicolor tunable long‐lived emission. Moreover, this switching process can be reversibly modulated over multiple cycles under alternating UV and visible photoirradiation. Finally, the prepared switch is successfully applied to photocontrolled multicolor cell labeling to offer a new approach for the design and fabrication of novel advanced light‐responsive RTP materials in aqueous environments.

Electrostatic co-assembly of nanoparticles with oppositely charged small molecules into static and dynamic superstructures.

Coulombic interactions can be used to assemble charged nanoparticles into higher-order structures, but the process requires oppositely charged partners that are similarly sized. The ability to mediate the assembly of such charged nanoparticles using structurally simple small molecules would greatly facilitate the fabrication of nanostructured materials and harnessing their applications in catalysis, sensing, and photonics. Here we show that small molecules having as few as three electric charges can effectively induce attractive interactions between oppositely charged nanoparticles in water. These interactions can guide the assembly of charged nanoparticles into colloidal crystals of a quality previously only thought to result from their cocrystallization with oppositely charged nanoparticles of a similar size. Transient nanoparticle assemblies can be generated using positively charged nanoparticles and multiply charged anions that are enzymatically hydrolyzed into mono- and/or dianions. Our findings demonstrate an approach for the facile fabrication, manipulation, and further investigation of static and dynamic nanostructured materials in aqueous environments.

Magnetically-stimulated transformations in the nanostructure of PEGylated phytantriol-based nanoparticles for on-demand drug release

Lipid-based liquid crystalline (LLC) systems are formed by the self-assembly of lipid materials in aqueous environments. The internal nanostructures of LLC systems can be manipulated using remote stimuli and have the potential to serve as ‘on-demand’ drug delivery systems. In this study, a magnetically-responsive system that displayed a transition in nanostructure from liposomes to cubosomes/hexasomes under external alternating magnetic field (AMF) was established by the incorporation of iron oxide nanoparticles (IONPs) into a PEGylated phytantriol (PHYT)-based LLC system. Small angle X-ray scattering (SAXS) was utilized to assess the equilibrium phase behaviour of the systems with different compositions of the lipids to find the optimized formulation. Time-resolved SAXS was then used to determine the dynamic transformation of nanostructures of the IONP-containing systems with the activation of AMF. The formulation containing PHYT and DSPE-PEG2000 at a 95 to 5 molar percent ratio produced a transition from lamellar phase to bicontinuous cubic phase, showing a slow-to-fast drug release profile. Inclusion of either 5 nm or 15 nm IONPs imparted magnetic-responsiveness to the system. The magnetically-responsive system produced an ‘on-demand’ drug delivery system from which the drug release was able to be triggered externally by AMF-stimulation.

The Potential for PE Microplastics to Affect the Removal of Carbamazepine Medical Pollutants from Aqueous Environments by Multiwalled Carbon Nanotubes.

Microplastics are ubiquitous in aquatic environments and interact with other kinds of pollutants, which affects the migration, transformation, and fate of those other pollutants. In this study, we employ carbamazepine (CBZ) as the contaminant to study the influence of polyethylene (PE) microplastics on the adsorption of CBZ pollutants by multiwalled carbon nanotubes (MCNTs) in aqueous solution. The adsorption capacity of CBZ by MCNTs in the presence of PE microplastics was obviously lower than that by MCNTs alone. The influencing factors, including the dose of microplastics, pH, and CBZ solution concentration, on the adsorption of CBZ by MCNTs and MCNTs−PE were thoroughly investigated. The adsorption rate of CBZ by MCNTs decreased from 97.4% to 90.6% as the PE microplastics dose increased from 2 g/L to 20 g/L. This decrease occurred because the MCNTs were coated on the surface of the PE microplastics, which further decreased the effective adsorption area of the MCNTs. This research provides a framework for revealing the effect of microplastics on the adsorption of pollutants by carbon materials in aqueous environments.

A Review of Photoelectrocatalytic Reactors for Water and Wastewater Treatment

The photoexcitation of suitable semiconducting materials in aqueous environments can lead to the production of reactive oxygen species (ROS). ROS can inactivate microorganisms and degrade a range of chemical compounds. In the case of heterogeneous photocatalysis, semiconducting materials may suffer from fast recombination of electron–hole pairs and require post-treatment to separate the photocatalyst when a suspension system is used. To reduce recombination and improve the rate of degradation, an externally applied electrical bias can be used where the semiconducting material is immobilised onto an electrically conducive support and connected to a counter electrode. These electrochemically assisted photocatalytic systems have been termed “photoelectrocatalytic” (PEC). This review will explain the fundamental mechanism of PECs, photoelectrodes, the different types of PEC reactors reported in the literature, the (photo)electrodes used, the contaminants degraded, the key findings and prospects in the research area.

Structure and dynamics of water in TiO2 nano slits: The influence of interfacial interactions and pore sizes

Abstract The interaction of water with TiO2 surfaces is of enduring interest because of wide applications of the TiO2 materials in aqueous environments. The structure and dynamic properties of water molecules in TiO2 nanopores are crucial as increasingly TiO2 materials are synthesized into nanoporous structures. In this work, the structural and dynamic properties of water molecules in nanoscale slit pores of TiO2 are investigated, by using three sets of force field models for the water- TiO2 interaction, as well as four TiO2 slit pore widths. It is concluded that the water- TiO2 interaction dominates the interfacial structure of water molecules, while the dynamic properties of water molecules are primarily influenced by the slit width in both interfacial and central regions. These findings indicate that both of the fluid properties and the interactions of fluids with pore wall will determine the transport properties of fluid in nanopores. If the pore size is large enough, e.g. 1.0 nm or larger in this work, the transport properties will be determined most by the fluids themselves. For the cases of pores whose sizes are in the range of interfacial region, the influences of pore size and interfacial interaction will interfere each other.

Improving the hydrostability of ZIF-8 membrane by biomolecule towards enhanced nanofiltration performance for dye removal

Zeolitic imidazolate frameworks-8 (ZIF-8)/polymer composite membranes have shown great promise in gas separation, catalysis and biotechnology due to their microporous nature. However, the structural instability against protonation limits the application of ZIF-8 materials in aqueous environments, e.g. water treatment membranes. In this study, a ZIF-8 nanocomposite membrane with satisfactory hydrostability was explored. More specifically, a series of composite ZIF-8 thin film containing DNA molecules were deposited on dopamine-modified polysulfone (PSF) substrates via an in situ growth under ambient conditions. The incorporation of DNA molecules significantly enhanced the hydrophilicity of the composite membrane (water contact angle reduced from 66.9° to 29.2°). Compared with the pure ZIF-8 counterpart, the DNA-containing ZIF-8 membrane exhibited higher water flux, accompanied with higher rejections for organic dyes and inorganic salt ions. More importantly, the DNA-containing ZIF-8 membrane showed significantly enhanced water stability and anti-fouling property during the filtration tests. The utilization of biomacromolecules to stabilize ZIF membrane enables potential applications for ZIF membranes for wider water-related applications.

Stress wave in monosized bead string with various water contents

Wet granular materials exhibit unique physical and mechanical properties, especially in relation to wave propagation, which is quite different from dry granular materials. In this paper, by introducing the capillary bridge force into the discrete element method, the stress wave in mono-sized bead string with various water content has been studied. First the vibration of two particles with liquid bridge has been analyzed. The presence of the liquid bridge force causes the kinetic response of the particles to exhibit completely different properties than that of the dry particles. The equilibrium position is affected by both the physical properties of the particles and the liquid bridge properties. Then the wave propagation behaviors in a mono-sized bead string have been analyzed. According to whether the liquid bridge volume has an effect on granular motion, the whole process can be divided into two stages. Stage I, particles are physically contacted with each other directly. The influence of liquid bridge force is independent of the bridge volume. Stage II, particles start to oscillate back and forth at their equilibrium positions, the influence of the liquid bridge force becomes related to the bridge volume. The kinetic energy dissipation first decreases and then increases. A U-shaped trend appears throughout the dissipation process. In our work, the mechanical properties of wet granular materials are studied from two levels: particle vibration and wave propagation, which will provide theoretical guidance for the application of granular materials in aqueous environment.

Dye-sensitization enhances photoelectrochemical performance of halide perovskite CH3NH3PbI3 photoanode in aqueous solution

Owing to superior optoelectronic performance, halide perovskite-based materials have been widely applied in energy conversion systems such as solar cells. However, the halide-perovskite-based photoelectrochemical systems with the halide perovskite materials photoanode directly placed in aqueous solution receive insufficient attention. In this manuscript, for the first time a photoelectrochemical setup based on a dye-sensitized CH3NH3PbI3 photoanode directly immersed in water solution is demonstrated. The photoelectrochemical performance in the aqueous solution under the visible light irradiation is activated by a simple deposition of commercial dye on halide perovskite surfaces. The interfacial structures of the molecule/perovskite hybrid systems are analyzed via the density-functional theory calculations, indicating effective passivation of multiple potential surface charge traps. This study helps the fundamental understanding of the halide perovskite materials in aqueous environment, and highlights the concept of dye-sensitized halide perovskite photoelectrochemical system, which combines the virtues of dye-sensitized systems and halide perovskite materials for energy conversion applications.

Ionic-Strength Dependence of Electron Mobility of Back-Gate Bilayer MoS2 FETs in Aqueous Electrolyte Solutions

In the past few years, atomically thin layered semiconductor materials have attracted numerous interest because of the potential of using those materials to establish liquid–semiconductor sensor systems towards next-generation biological/chemical sensing applications. However, the information regarding the electrical characteristics of 2D materials in aqueous environments for advancing the development of such emerging sensor systems is still unclear. In this report, we have synthesized the bilayer molybdenum disulfide (MoS2) nanomaterials by the chemical vapor deposition method. The layer number of the as-grown MoS2 materials were characterized by using both the Raman spectra and the atomic force microscope (AFM). The selected bilayer MoS2 materials were transferred to a silicon substrate covered with 100 nm-thick SiO2 dielectric layer. The source/drain electrode patterns of the back-gate FETs were defined using an electron beam lithography, followed by the deposition process of the gold thin layer. Importantly, the source/drain electrodes were passivated by the PR layer for reducing the leakage current. After the FET fabrication, the electrical properties of bilayer MoS2 FETs were measured under both the ambient condition and the different concentrations of KCl aqueous electrolyte solutions. From the experimental result of the extracted field-effect mobility, we can evidently find that, when the ionic strength of the KCl electrolyte solution was increased from 0.1 μM to 0.1 M, the values of the ratio of the electron mobility extracted at the aqueous solution to that extracted at the air environment revealed a decreasing trend. The scattering from the ions in the aqueous electrolyte solutions may presumably give rise to the degradation of electron mobility. This report provides information regarding the dependence of the ionic strength on the mobility of atomically thin layered FETs for future sensor applications.

Rheological Characteristics of 2D Titanium Carbide (MXene) Dispersions: A Guide for Processing MXenes.

Understanding the rheological properties of two-dimensional (2D) materials in suspension is critical for the development of various solution processing and manufacturing techniques. 2D carbides and nitrides (MXenes) constitute one of the largest families of 2D materials with >20 synthesized compositions and applications already ranging from energy storage to medicine to optoelectronics. However, in spite of a report on clay-like behavior, not much is known about their rheological response. In this study, rheological behavior of single- and multilayer Ti3C2T x in aqueous dispersions was investigated. Viscous and viscoelastic properties of MXene dispersions were studied over a variety of concentrations from colloidal dispersions to high loading slurries, showing that a multilayer MXene suspension with up to 70 wt % can exhibit flowability. Processing guidelines for the fabrication of MXene films, coatings, and fibers have been established based on the rheological properties. Surprisingly, high viscosity was observed at very low concentrations for solutions of single-layer MXene flakes. Single-layer colloidal solutions were found to exhibit partial elasticity even at the lowest tested concentrations (<0.20 mg/mL) due to the presence of strong surface charge and excellent hydrophilicity of MXene, making them amenable to fabrication at dilute concentrations. Overall, the findings of this study provide fundamental insights into the rheological response of this quickly growing 2D family of materials in aqueous environments as well as offer guidelines for processing of MXenes.

Probing Electron Mobility of Monolayer MoS2 Field‐Effect Transistors in Aqueous Environments

AbstractAtomically thin layered 2D semiconductors have inspired intense interest in building hybrid liquid–semiconductor electronic systems for next‐generation biological/chemical sensing applications. There remains, however, a lack of understanding of the electrical characteristics of 2D materials in aqueous environments and, thereby, much useful information for advancing the development of such emerging sensor systems. In this study, the effects of aqueous environments on the field‐effect electron mobility (µFE) of monolayer molybdenum disulfide (MoS2) field‐effect transistors (FETs), using various operational modes (back‐gating, liquid‐gating, and dual‐gating), are explored at room temperature. The value of µFE of the MoS2 exposed to deionized (DI) water is much greater than that treated merely under ambient conditions, presumably the result of a dielectric screening effect. When the DI water is changed to a biologically compatible buffer (0.01 or 0.1 m potassium phosphate buffer) at pH 7, the value of µFE decreases significantly. Further investigation into the possible origin of the degraded mobility suggests that the ions in the aqueous solutions play an important role as additional scatterers. This report should enhance the understanding of the mechanisms of mobility scattering in liquid–semiconductor 2D FET systems for applications in hybrid electronics, bioelectronics, and nanosensors.

Amine-Reactive Azlactone-Containing Nanofibers for the Immobilization and Patterning of New Functionality on Nanofiber-Based Scaffolds.

We report the design of amine-reactive polymer nanofibers and nonwoven reactive nanofiber mats fabricated by the electrospinning of azlactone-functionalized polymers. We demonstrate that randomly oriented nanofibers fabricated using a random copolymer of methyl methacrylate and 2-vinyl-4,4-dimethylazlactone contain intact and reactive azlactone groups that can be used to introduce new chemical functionality and modulate important interfacial properties of these materials (e.g., wetting behaviors) by postfabrication treatment with primary amine-based nucleophiles. The facile and "click-like" nature of these reactions permits functionalization under mild conditions without substantial changes to nanofiber or mat morphologies. This approach also enables the patterning of new functionality on mat-coated surfaces by treatment with bulk solutions of primary amines or by using methods such as microcontact printing. Further, these reactive mats can also, themselves, be contact-transferred or "printed" onto secondary surfaces by pressing them into contact with other amine-functionalized objects. Finally, we demonstrate that functionalization with hydrophobic amines can increase the stability of these materials in aqueous environments and yield hydrophobic nanofiber scaffolds useful for the design of "slippery" liquid-infused materials. The approaches reported here enable the introduction of new properties to reactive polymer mats after fabrication and, thus, reduce the need to synthesize individual functional polymers prior to electrospinning to achieve new properties. The azlactone chemistry used here broadens the scope of reactions that can be used to functionalize polymer nanofibers and is likely to prove general. We anticipate that this approach can be used with a range of amines or other nucleophiles (e.g., alcohols or thiols) to design nanofibers and reactive nanofiber-based materials with new physical properties, surface features, and behaviors that may be difficult to achieve by the direct electrospinning of conventional materials or other functional polymers.

Natural polymeric microspheres for modulated drug delivery

Microspheres can be regarded as a suitable platform for the development of ad hoc drug delivery systems, since the targeted release of a therapeutic agent can effectively contribute to support and improve a pharmacological protocol. However, several crucial factors related to the selection of materials, drugs and fabrication techniques should be critically analyzed in order to enhance the expected performance. Dealing with highly compatible materials, e.g. naturally-derived polymers and “green” reagents, can be a valid approach. For this aim, gelatin, chitosan and blend microspheres were produced by emulsion technique simply using distilled water and olive oil. Necessarily, due to the intrinsic instability of the selected materials in aqueous environment, microspheres were cross-linked with genipin, an extremely low cytotoxic agent, at three different concentration (i.e., 0.1, 0.5, 1% w/v). Collected microspheres were then loaded with methylene blue (MB), as drug model. Morphological analysis revealed homogeneous microspheres characterized by an average diameter comprised in the range 42–54μm. In vitro MB temporal delivery was assessed until complete release, which occurred in about 3days for gelatin and 30days for chitosan microspheres. Nanoindentation analysis was performed to evaluate how polymers and genipin influenced the mechanical properties of microspheres. Finally, the effect of released MB was investigated by means of chicken embryo chorioallantoic membrane assay, highlighting anti-angiogenic properties for gelatin differently from chitosan and blend microspheres.

On the dispersion of lithium-sulfur battery cathode materials effected by electrostatic and stereo-chemical factors of binders

Sodium carboxymethyl cellulose-styrene butadiene rubber (CMC-SBR), sodium alginate (SA) and LA132 are utilized as the polymer binders for the cathodes of Li-S batteries to study their dispersion mechanism on the cathode materials and the consequent influence on the performance of Li-S batteries. Zeta potential tests, differential scanning calorimetry analysis and calculations of the rotational barriers of the links of the polymer chains by General Atomic and Molecular Electronic Structure System (GAMESS) reveal that higher charge densities and better chain flexibility of the binders promise the dispersion of the downsized cathode materials. LA132 is found to have optimal characteristic for dispersing and stabilizing the cathode materials in aqueous environment. The cycling performance and SEM images of the cathodes demonstrate that cathodes with higher dispersion degree achieve higher discharge capacities. The electrochemical impedance spectroscopy (EIS) results further support that better dispersed cathodes have lower impedance resulting from their well established conducting frameworks.

Electrochemical phase diagrams for Ti oxides from density functional calculations

Developing an accurate simulation method for the electrochemical stability of solids, as well as understanding the physics related with its accuracy, is critically important for improving the performance of compounds and predicting the stability of new materials in aqueous environments. Herein we propose a workflow for the accurate calculation of first-principles electrochemical phase (Pourbaix) diagrams. With this scheme, we study the electrochemical stabilities of Ti and Ti oxides using density-functional theory. First, we find the accuracy of an exchange-correlation functional in predicting formation energies and electrochemical stabilities is closely related with the electronic exchange interaction therein. Second, the metaGGA and hybrid functionals with a more precise description of the electronic exchange interaction lead to a systematic improvement in the accuracy of the Pourbaix diagrams. Furthermore, we show that accurate Ti Pourbaix diagrams also require that thermal effects are included through vibrational contributions to the free energy. We then use these diagrams to explain various experimental electrochemical phenomena for the Ti--O system, and show that if experimental formation energies for Ti oxides, which contain contributions from defects owing to their generation at high (combustion) temperatures, are directly used to predict room temperature Pourbaix diagrams then significant inaccuracies result. In contrast, the formation energies from accurate first-principles calculations, e.g., using metaGGA and hybrid functionals, are found to be more reliable. Finally to facilitate the future application of our accurate electrochemical phase equilibria diagrams, the variation of the Ti Pourbaix diagrams with aqueous ion concentration is also provided.