Double Ion Research Articles

Co-precipitation reaction: A facile strategy for designing hierarchical porous carbon nanosheets for EDLCs and zinc-ion hybrid supercapacitors

Hierarchical porous carbon is a valuable electrode material for electrochemical energy storage devices by virtue of its high specific surface area, excellent conductivity, and large pore volume. Herein, a simple, convenient and cheap self-made Fe-based template strategy is innovated to prepare hierarchical porous carbon employing coal chemical byproducts anthracene as carbon precursor, which is utilized as electrode materials of electrical double layer capacitors (EDLCs) and zinc ions hybrid supercapacitors (ZHSs). Benefiting from the high specific surface area (2085.1 m2 g−1), feasible micropore content (0.28 cm3 g−1), suitable oxygen content (11.57 at%) and two-dimensional nanosheet structure, the optimal sample delivered a high specific capacitance value of 183.5 F g−1 at 0.05 A/g and excellent rate capability (109.5 F g−1 at 20 A/g) for symmetric supercapacitor. Meanwhile, the as-fabricated ZHSs exhibited remarkable specific capacitance (181.67 mAh/g at 0.05 A/g), superior energy density (145.2 Wh kg−1), high power density (14.5 kW kg−1) and splendid cycling stability (∼91.25 % after 40,000 charge/discharge cycles at 2 A g−1). This work affords a new idea for the synthesis of template carbon using a feasible and low-cost co-precipitation reaction route and has great significance for the development of high-performance electrochemical energy storage device.

Hydration-induced protomer switching in p-aminobenzoic acid studied by cold double ion trap infrared spectroscopy.

Para-Aminobenzoic acid (PABA) is a benchmark molecule to study solvent-induced proton site switching. Protonation of the carboxy and amino groups of PABA generates O- and N-protomers of PABAH+, respectively. Ion mobility mass spectrometry (IMS) and infrared photodissociation (IRPD) studies have claimed that the O-protomer most stable in the gas phase is converted to the N-protomer most stable in solution upon hydration with six water molecules in the gas-phase cluster. However, the threshold size has remained ambiguous because the arrival time distributions in the IMS experiments exhibit multiple peaks. On the other hand, IRPD spectroscopy could not detect the N-protomer for smaller hydrated clusters because of broad background due to annealing required to reduce kinetic trapping. Herein, we report the threshold size for O → N protomer switching without ambiguity using IR spectroscopy in a double ion trap spectrometer from 1300 to 1800 cm-1. The pure O-protomer is prepared by electrospray, and size-specific hydrated clusters are formed in a reaction ion trap. The resulting clusters are transferred into a second cryogenic ion trap and the distribution of O- and N-protomers is determined by mid-IR spectroscopy without broadening. The threshold to promote O → N protomer switching is indeed five water molecules. It is smaller than the value reported previously, and as a result, its pentahydrated structure does not support the Grotthuss mechanism proposed previously. The extent of O → N proton transfer is evaluated by collision-assisted stripping IR spectroscopy, and the N-protomer population increases with the number of water molecules. This result is consistent with the dominant population of the N-protomer in aqueous solution.

Experimental investigation of divalent ions and screening in smart water on calcite rock surface

Massive demand for fossil fuel against limited available oil conventional reservoirs worldwide highlights that innovative enhanced oil recovery method. Nowadays, due to the accessibility of seawater and rivers, smart water and low salinity water injection have gained more attention. This paper addresses the mechanisms behind smart water injection and studies a real case from a carbonate oil reservoir. For this purpose, contact angle measurement was employed to screen and find the best smart water composition among different types of water. A core flooding experiment was used to evaluate the performance of the smart water injection in calcite rock. Two different scenarios were implemented in the core displacement experiment to examine the effect of divalent ions. Based on the experimental results, the main mechanism behind the smart water injection is the wettability alteration of the calcite rock surface. Also, as the most central divalent ions, an increase in calcium ions has been effective in increasing the water wetness of the rock surface, resulting in river water with double calcium ion content as the best smart water. [Received: November 8, 2021; Accepted: June 2, 2022]

Simulation of the cyclic voltammetric response of an outer-sphere redox species with inclusion of electrical double layer structure and ohmic potential drop.

A finite-element model has been developed to simulate the cyclic voltammetric (CV) response of a planar electrode for a 1e outer-sphere redox process, which fully accounts for cell electrostatics, including ohmic potential drop, ion migration, and the structure of the potential-dependent electric double layer. Both reversible and quasi-reversible redox reactions are treated. The simulations compute the time-dependent electric potential and ion distributions across the entire cell during a voltammetric scan. In this way, it is possible to obtain the interdependent faradaic and non-faradaic contributions to a CV and rigorously include all effects of the electric potential distribution on the rate of electron transfer and the local concentrations of the redox species Oz and Rz-1. Importantly, we demonstrate that the driving force for electron transfer can be different to the applied potential when electrostatic interactions are included. We also show that the concentrations of Oz and Rz-1 at the plane of electron transfer (PET) significantly depart from those predicted by the Nernst equation, even when the system is characterised by fast electron transfer/diffusion control. A mechanistic rationalisation is also presented as to why the electric double layer has a negligible effect on the CV response of such reversible systems. In contrast, for quasi-reversible electron transfer the concentrations of redox species at the PET are shown to play an important role in determining CV wave shape, an effect also dependant on the charge of the redox species and the formal electrode potential of the redox couple. Failure to consider electrostatic effects could lead to incorrect interpretation of electron-transfer kinetics from the CV response. Simulated CVs at scan rates between 0.1 and 1000 V s-1 are found to be in good agreement with experimental data for the reduction of 1.0 mM Ru(NH3)63+ at a 2 mm diameter gold disk electrode in 1.0 M potassium nitrate.

A one-dimensional conductive metal-organic framework with extended π-d conjugated nanoribbon layers

Conductive metal-organic frameworks (MOFs) have performed well in the fields of energy and catalysis, among which two-dimensional (2D) and three-dimensional (3D) MOFs are well-known. Here, we have synthesized a one-dimensional (1D) conductive metal-organic framework (MOF) in which hexacoordinated 1,5-Diamino-4,8-dihydroxy-9,10-anthraceneedione (DDA) ligands are connected by double Cu ions, resulting in nanoribbon layers with 1D π-d conjugated nanoribbon plane and out-of-plane π-π stacking, which facilitates charge transport along two dimensions. The DDA-Cu as a highly conductive n-type MOF has high crystalline quality with a conductivity of ~ 9.4 S·m−1, which is at least two orders of magnitude higher than that of conventional 1D MOFs. Its electrical band gap (Eg) and exciton binding energy (Eb) are approximately 0.49 eV and 0.3 eV, respectively. When utilized as electrode material in a supercapacitor, the DDA-Cu exhibits good charge storage capacity and cycle stability. Meanwhile, as thse active semiconductor layer, it successfully simulates the artificial visual perception system with excellent bending resistance and air stability as a MOF-based flexible optoelectronic synaptic case. The controllable preparation of high-quality 1D DDA-Cu MOF may enable new architectural designs and various applications in the future.

Top-down integration of suspended N+/P/N+ silicon-nanowire-based ion-sensitive field effect transistors for pH analysis at the submicronic scale

A technological process was proposed in order to integrate fully silicon-nanowire-based field-effect nanodevices on a silicon-on-insulator (SOI) substrate. Thanks to a double reactive ion etching process of the SOI silicon upper layer as well as to a "SiO2 thermal oxidation growth / Al2O3 atomic layer deposition" gate process, silicon-nanowire-based field-effect transistors (SiNW-FET) and silicon-nanowire-based ion-sensitive field-effect transistors (SiNW-ISFET) were fabricated. Focuses were brought on (i) the integration of a suspended N+/P/N+ double-junction structure (gate length: ∼ 0.75 μm and ∼ 3.75 μm), (ii) the fabrication of a SiO2/Al2O3 all-around surrounding gate structure, (iii) the achievement of low nanowire sections (width: ∼ 150 nm, height: ∼ 200 nm), and (iv) the final adaptation to the liquid phase analysis thanks to SU8-based wafer-level packaging. According to the proposed process, SiNW-FET and SiNW-ISFET devices showed excellent electrical characteristics in terms of leakage resistance ROFF, subthreshold current slope and ION/IOFF maximal ratio. SiNW-ISFET devices were finally studied for the pH analysis at the submicronic scale (analysed volumes: ∼ 10 pL), evidencing standard potentiometric detection sensitivity (∼ 56 mV/pH), as well as excellent amperometric detection sensitivity (∼ 0.4 current decade per pH) in subthreshold regime.

A Cross-Scale Framework for Modelling Chloride Ions Diffusion in C-S-H: Combined Effects of Slip, Electric Double Layer and Ion Correlation.

Water and chloride ions within pores of cementitious materials plays a crucial role in the damage processes of cement pastes, particularly in the binding material comprising calcium-silicate-hydrates (C-S-H). The migration mechanism of water and chloride ions restricted in C-S-H nanopores is complicated due to the presence of interfacial effects. The special mechanical properties of the solid-liquid interface determine the importance of boundary slip and Electric Double Layer (EDL) and ion diversity in pore solutions determines the difference of the EDL and the stability of water film slip. A cross-scale model covering slip effects, time-varying of EDL and ion correlation needs to be developed so that the interfacial effects concentrated at the pore scale can be extended to affect the overall diffusivity of C-S-H. The statistics of pore size distribution and fractal dimension were used to quantitatively compare the similarities between model and C-S-H structure, thus proving the reliability of cross-scale reconstructed C-S-H transmission model. The results show that the slip effect is the dominant factor affecting the diffusion ability of C-S-H, the contribution of the slip effect is up to 60% and the contribution rate of EDL time-varying only up to about 15%. Moreover, the slip effect is sensitive to both ion correlation and C-S-H inhomogeneity and EDL time-varying is almost insensitive to ion correlation changes. This quantification provides a necessary benchmark for understanding the destructiveness of cement-based materials in the salt rich environment and provides new insights into improving the durability of concrete by changing the solid-liquid interface on the micro-nanoscale.

Radiative cooling of polyyne anions: C4H- and C6H.

Time-dependent photodetachment action spectra for the linear hydrocarbon anions C4H- and C6H- are investigated using the cryogenic Double ElectroStatic Ion Ring ExpEriment. The radiative cooling characteristics of these ions on the millisecond to seconds timescale are characterized by monitoring changes in their spectra as the ions cool by spontaneous infrared (IR) emission. The average cooling rates, extracted using Non-negative Matrix Factorization, are fit with 1/e lifetimes of 19 ± 2 and 3.0 ± 0.2s for C4H- and C6H-, respectively. The cooling rates are successfully reproduced using a simple harmonic cascade model of IR emission. The ultraslow radiative cooling dynamics determined in this work provide important data for understanding the thermal cooling properties of linear hydrocarbon anions and for refining models of the formation and destruction mechanisms of these anions in astrochemical environments.

Gentle nano-electrospray ion source for reliable and efficient generation of microsolvated ions

We present herein the design of a nano-electrospray ion source capable of reliable generation of large quantities of microsolvated ions. The source is based on a triple molecular skimmer scheme and can be quickly tuned to generate bare ions or their ionic complexes with up to more than 100 solvent molecules retained from solution. The performance of this source is illustrated by recording the mass spectra of distributions of ionic complexes of protonated water, amino acids, and a small protein ubiquitin. Protonated water complexes with more than 110 molecules and amino acids with more than 45 water molecules could be generated. Although the commercial ion source based on the double ion funnel design with orthogonal injection, which we used in our laboratory, is more efficient in generating ions than our triple skimmer ion source, they both exhibit comparable short-term stability in generating bare ions. In return, only the new source is capable of generating microsolvated ions.

Simple Monovalent Metal Ion Logical Order to Regulate the Secondary Conformation of G-Quadruplex.

Based on the reactions of different sequences with single ions K+, Na, NH4 +, double ions high + low, low + high, and triple ions with different addition orders, the best stable ion combinations of 12 quadruplexes with different DNA sequences were reported. From the fluorescence spectrum, except for HT-V15 and PW17 and AS1411 and HT-V18, the structural stability of G-quadrangle formed basically follows a certain rule. In terms of this experiment, according to circular dichroism, the antiparallel quadrupole structure has the largest proportion among quadrupole structures, and 12 optimal DNA addition schemes and sequences have been obtained through exploration. It is worth mentioning that, on the whole, the best addition scheme of AS1411 and HT-V18 is a three-ion scheme, which provides an effective reference for similar experiments in the future.

Mg1-xNixFe2-xCrxO4 synthesis via hydrothermal route: Effect of doping on the structural, optical, electrical, magnetic and photocatalytic properties

A pristine MgFe2O4 and a series of Ni and Cr substituted magnesium ferrite NPs have been fabricated via hydrothermal route. The influence of double ions substitution on MgFe2O4 was examined attributed to structural, optical, electrical, magnetic and photocatalytic properties. X-ray diffraction analysis revealed cubic geometry having fd3m space group with an average crystalline size in 25–33 nm. From hysteresis loop saturation polarization (Ps), coercivity and remanence polarization (Pr)was evaluated and found that the value of Ps and Pr were improved on increasing dopants content. VSM analysis confirms the ferromagnetic behavior of Mg1-xNixFe2-xCrxO4. Furthermore, thedielectric loss decreased by increasing frequency as well as the amount of dopant. UV–Vis absorption spectrum exhibited red-shift and band-gap energy reduced i.e., 2.58 to 2.29 eV. PCA study evaluated using crystal violet (CV) dye and Mg1-xNixFe2-xCrxO4 NPs exhibited higher efficiency and 97 % dye degradation was observed for Mg1-xNixFe2-xCrxO4 versus MgFe2O4 (59 %) under sunlight irradiation in 100 min. Moreover, the stability of NPs was confirmed through recycling experiment and Mg1-xNixFe2-xCrxO4 showed promising stability and reusability. Thus, the enhanced photocatalytic activity under solar light revealed its application for remediation of dyes in industrial waste under sunlight irradiation, it will make the process highly feasible.

Ag+ and Ca+ single implantation and co-implantation induced the cell growth and antibacterial activity of TiN/Ti-6Al-4V

In order to inhibit titanium alloy's (Ti-6Al-4V) release of toxic ions (e.g., V4+ and Al3+) in the humoral environment, titanium nitride (TiN) film was first coated on Ti-6Al-4V in this paper. Then, silver (Ag) and calcium (Ca) ions were single implanted or co-implanted into the TiN flim respectively to provide significant effects on the osteogenic enhancement and antibacterial responses of TiN film. The results showed that the roughness, hydrophilicities and protein adsorption capacities of samples were all increased after ion implantation. In addition, compared with the single performance improvement over single ion implantation, the Ag + Ca ions co-implanted TiN sample (Ag/Ca-TiN) showed the best cell adhesion, cell proliferation and excellent antibacterial activity. And the study of bacteria-cell co-culture showed that Ag/Ca-TiN could help cells overcome bacteria and occupy the sample surface. These results indicate that the synergy obtained by double ions via co-implantation is the key factor in the osteogenic and antibacterial enhancements.

Formations of anode double layer and ion beam in bipolar-pulse HiPIMS (BP-HiPIMS)

As an emerging ion acceleration plasma source, the bipolar-pulse high power impulse magnetron sputtering (BP-HiPIMS) discharge provides an effective approach to improve deposited ion energy and tailor the film properties for a large range of applications. The ion acceleration mechanism in BP-HiPIMS discharge is very vital but still unclear now. In the present work, the ion acceleration mechanism is systematically investigated via the experimental measurements, particle-in-cell/Monte Carlo collision (PIC-MCC) simulation, and theoretical model together. In the experiment part, the floating potential V f and the ion velocity distribution function (IVDF) have been measured via the Langmuir probe and the retarding field energy analyser (RFEA) respectively. The measurements show that the V f at the downstream drops from +80 V to ∼+40 V after applying the positive pulse for ∼75 μs, suggesting the formation of the double layer. Correspondingly, the IVDF changes from the unimodal Maxwellian distribution to the bimodal distribution, suggesting the existence of the ion beam. The PIC-MCC simulation results clearly show the development process of the double layer and ion beam. A theoretical model is introduced to explore the complex plasma dynamics in the experiment and simulation. The theoretical results illustrate that (i) the sheath in front of the target surface prefers an ion sheath rather than an electron sheath, (ii) the stable position of the double layer boundary is in the magnetic null point, (iii) the potential drop across the boundary is influenced by the gas pressure p. These important theoretical results are well consistent with the measurements and simulation. In addition, the oscillation of the double layer boundary and the instabilities of the ions are briefly discussed by combining the previous works.

Zinc-doped calcium silicate additive accelerates early angiogenesis and bone regeneration of calcium phosphate cement by double bioactive ions stimulation and immunoregulation

Calcium phosphate cement (CPC), a popular injectable bone defect repairing material, has deficiencies in stimulating osteogenesis and angiogenesis. To overcome the weaknesses of CPC, zinc-doped calcium silicate (Zn-CS) which can release bioactive silicon (Si) and zinc (Zn) ions was introduced to CPC. The physicochemical and biological properties of CPC and its composites were evaluated. Firstly, the most effective addition content of calcium silicate (CaSiO3, CS) in promoting the in vitro osteogenesis was first sorted out. On this basis, the most effective Zn doping content in CS for improving osteogenic differentiation of CPC-based composites was screened out. Finally, the immunoregulation of CS/CPC and Zn-CS/CPC in promoting angiogenesis and osteogenesis was studied. The results showed that the most effective incorporation content of CS was 10 wt%. Zn at a doping content of 30 mol% in CS (30Zn-CS) further enhanced the osteogenic capacity of CS/CPC and simultaneously maintained excellent proangiogenic activity. CS/CPC and 30Zn-CS/CPC promoted the recruitment of macrophages and enhanced M2 polarization while inhibiting M1 polarization, which was beneficial to the early vascularization as well as subsequent new bone formation. When implanted into the femoral condylar defects of rabbits, 30Zn-CS/CPC showed high in vivo materials degradation rate, angiogenesis and osteogenesis, due to the synergistic effects of Si and Zn on bio-stimulation and immunoregulation. This study shed light on the synergistic effects of Si and Zn on regulating the angiogenic, osteogenic, and immunoregulatory activity, and 30Zn-CS/CPC is expected to repair the lacunar bone defects effectively.

Enhancing Structural Stability and Electrochemical Properties of Co-Less Ni-Rich Layer Cathode Materials by Fluorine and Niobium Co Doping

A solid-state approach was used to synthesize Li(Ni0.925Co0.03Mn0.045)0.996Nb0.004O1.98F0.02 with double ion doping. The structure parameters, micromorphology, and element valence distribution of all materials were thoroughly investigated by XRD, SEM, EDS, XPS, and HR-TEM. The results show that the distribution of F and Nb is uniform both on the surface and inside the particles and that F and Nb ions have an impact on the valence state of Ni ions on the surface of the material. In addition, the lattice parameter c is raised and the (003) crystal plane spacing is widened by the introduction of both F and Nb ions. The Li(Ni0.925Co0.03Mn0.045)0.996Nb0.004O1.98F0.02 electrode shows a higher discharge specific capacity (169.12 mAh g–1) at 10C and excellent cycling performance with a capacity retention of 83.60% after 150 cycles. Comparison of CV, dV/dq, EIS, SEM, and HR-TEM after cycling for all electrodes reveals that the particles doped with F and Nb maintained intact morphology and showed varying degrees of decrease in polarization and impedance.

A bionic composite hydrogel with dual regulatory functions for the osteochondral repair

Due to the avascular nature of cartilage, it is difficult to heal and regenerate spontaneously after injury. At present, tissue engineering has become a promising strategy for repairing damaged cartilage, but the use of seed cells and growth factors is limited. In addition, the importance of mechanical compatibility of scaffold materials is often ignored. In this study, osteochondral scaffold was designed as a bilayer structure with a dense γ-Polyglutamic acid/carboxymethyl chitosan/bacterial cellulose (PGA/CMCS/BC) hydrogel cartilage layer and a porous nano HA-containing PGA/CMCS/BC hydrogel osteogenic layer. In addition, bioactive ions were introduced into the hydrogel scaffold to adjust the mechanical and swelling properties of the material to match the mechanical properties of natural articular cartilage. At the same time, based on the structural characteristics of bone and cartilage, magnesium and copper ions were introduced into the double-layer hydrogel scaffold, respectively, to prepare the cartilage layer and the bone layer, which endowed the material with excellent antibacterial properties and achieved the purpose of the integrated repair of bone and cartilage. The results showed that, after adding magnesium ions, the tensile breaking strength of material was increased from 0.66 MPa to 1.37 MPa，the corresponding compression modulus of the material (strain 0–12%) increased from 0.15 MPa to 0.58 MPa whilst the maximum mass swelling rate decreased from 155% to 75%. The results of in vivo experiments show that the group with bioactive ions had a much better effect on the repair of osteochondral defects, compared with group without bioactive ions, demonstrating such double ion regulation strategy is a very practical strategy for the treatment of osteochondral defects.

Structure of Gas Phase Monohydrated Nicotine: Implications for Nicotine's Native Structure in the Acetylcholine Binding Protein.

We report a joint experimental-theoretical study of the never reported before structure and infrared spectra of gas phase monohydrated nicotine (NIC) and nornicotine (NOR) and use them to assign their protonation sites. NIC's biological activity is strongly affected by its protonation site, namely, the pyrrolidine (Pyrro-NICH+, anticipated active form) and pyridine (Pyri-NICH+) forms; however, these have yet to be directly experimentally determined in either the nicotinic acetylcholine receptor (nAChR, no water present) or the acetylcholine-binding protein (AChBP, a single water molecule is present) but can only be inferred to be Pyrro-NICH+ from the intermolecular distance to the neighboring residues (i.e., tryptophan). Our temperature-controlled double ion trap infrared spectroscopic experiments assisted by the collisional stripping method and high-level theoretical calculations yield the protonation ratio of Pyri:Pyrro = 8:2 at 240 K for the gas phase NICH+···(H2O) complex, which resembles the molecular cluster present in the AChBP. Therefore, a single water molecule in the gas phase enhances this ratio in NICH+ relative to the 3:2 for the nonhydrated gas phase NICH+ in a trend that contrasts with the almost exclusive presence of Pyrro-NICH+ in aqueous solution. In contrast, the Pyri-NORH+ protomer is exclusively observed, a fact that may correlate with its weaker biological activity.

Zn/Ti dual concentration-gradients surface doping to improve the stability and kinetics for Li-rich layered oxides cathode

Li-rich layered oxides (LLOs) with high specific capacity and low cost are potential cathode materials for next-generation lithium-ion batteries (LIBs). However, surface side reactions and structural instability at high operating voltages lead to poor cycling performance and sluggish kinetics. Herein, we report a novel Zn/Ti dual concentration-gradients surface modification strategy for LLOs, in which the Ti content gradually increases from the interface to the particle interior while the Zn content gradually decreases and finally remains at a relatively stable level. This strategy successfully induces the formation of functionalized surfaces and the Ti doping is more favorable to stabilize Mn4+, while the subsequent Zn doping is more benign to Ni3+. In addition, the strong Ti-O bond serves to stabilize the oxygen framework, while the blocking effect of Zn2+ in the Li layer inhibits the migration path of transition metal (TM) elements. In conclusion, the synergistic effect of double ion co-doping stabilizes the surface structure, improves the redox kinetics, and mitigates the degradation of electrochemical performance, with 24.1% increase in capacity retention compared to the pristine LLOs after 150 cycles at 0.5 C. This study provides an effective strategy for the design of robust LLOs cathode materials for LIBs.

Water-Gas Shift Catalyzed by Iridium-Vanadium Oxide Clusters IrVO2- with Iridium in a Rare Oxidation State of -II.

The discovery of compounds containing transition metals with an unusual and well-established oxidation state is vital to enrich our horizon on formal oxidation state. Herein, benefiting from the study of the water-gas shift reaction (CO + H2O → CO2 + H2) mediated with the iridium-vanadium oxide cluster IrVO2-, the missing -II oxidation state of iridium was identified. The reactions were performed by using our newly developed double ion trap reactors that can spatially separate the addition of reactants and are characterized by mass spectrometry and quantum-chemical calculations. This finding makes an important step that all the proposed 13 oxidation states of iridium (+IX to -III) have been known. The iridium atom in the IrVO2- cluster features the Ir═V double bond and resembles chemically the coordinated oxygen atom. A reactivity study demonstrated that the flexible role switch of iridium between an oxygen-atom like (Ir-IIVO2-) and a transition-metal-atom like behavior (Ir+IIVO3-) in different species can drive the water-gas shift reaction in the gas phase under ambient conditions. This result parallels and well rationalizes the extraordinary reactivity of oxide-supported iridium single-atom catalysts in related condensed-phase reactions.

Impact of salinity on fluid/fluid and rock/fluid interactions in enhanced oil recovery by hybrid low salinity water and surfactant flooding from fractured porous media

Wettability alteration of the porous medium from oil-wet (OW) to neutral-wet or even water-wet (WW) is proposed as one of the main mechanisms behind the enhanced oil recovery (EOR) by the Low Salinity Water Flooding (LSWF). However, our recent studies for a specific crude-oil/brine/rock of the oil reservoir in the Middle East, shows that LSW (diluted sea water) is not that much effective, neither to change the wettability of the surface nor to significantly increase the oil recovery factor. This obstacle becomes more challenging when we deal with fractured formations, where the imbibition of injected fluid from fracture into matrix and its propagation within the matrix, is the main macroscopic mechanism of the EOR. Chemical EOR, in which the chemical additive is added to the injecting brine, is one of the hybrid techniques which can boost oil recovery in such cases. In this study, CTAB as a cationic surfactant was added to brine solutions with different ionic strengths (i.e., sea water (SW), 10 times diluted sea water (10dSW) and 2 times concentrated sea water (2cSW)). Contact angle, zeta potential of both fluid/fluid and fluid/rock surfaces, and IFT tests were conducted to shed insight on interactions in crude oil/brine and rock/brine interfaces and the role of ionic strength. Finally, dynamic micromodel tests were performed in oil-wet fractured porous media to observe the impact of the added surfactant along with different ionic strength on displacement mechanisms and oil recovery.Experimental results show that neither electrical double layer expansion nor multiple ion exchange mechanisms cannot justify the observed detachment of oil droplets from the oil-wet substrates in the presence of the CTAB. Surfactant are absorbed on the oil/brine interface by the embedment of their hydrophobic tails in oil. Both surfactant molecules and the non-polar oil components (that are attracted to hydrophobic tail of surfactant molecules), are attracted to the solution via the hydrophilic parts of the surfactants. The effectiveness of this mechanism is dependent on both the concentration of the surfactant and concentration of the ions in brine.In the case that the aforementioned mechanism is adequately dominant and effective, the small droplets of oil will be detached from continuous oil bulk, resulting in oil to be broken to smaller droplets which enhances the detachment of the oil bulk from oil-wet substrates. This fluid/fluid interaction mechanism also promotes the imbibition of the aqueous phase into the matrix and also its propagation within the matrix.