NaOH Solution Research Articles

SnO2 nanoparticles: synthesis, characterization and photocatalytic activity

SnO2 nanoparticles have been synthesized using precipitation method and heat treatment. Firstly, SnCl4.5H2O was reacted with NaOH solution, and than the precipitate heat treated at 350 oC, 450 oC and 550 oC. The obtained materials were characterized by X-Ray diffraction (XRD) infrared spectra (IR) energy-dispersive X-ray spectroscopy (EDS) scanning electron microscopy (SEM) and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The photocatalytic degradation of rhodamine B (RhB) using SnO2 nanoparticles was investigated. The results show that the SnO2 nanoparticles exhibited a significantly enhanced photocatalytic activity. The photoactivity of SnO2 nanoparticles photocatalysts can be ascribed to the enhanced electron-hole separation.

Nanoarchitectonics of bamboo-based heterojunction photocatalyst for effective removal of organic pollutants

A high-performance photocatalyst with both efficient and reusable performance is essentially demanded for the purification of organic wastewater and the removal of indoor formaldehyde. However, recovery of photocatalyst particles from the reaction system remains a challenge. Herein, based on the abundant pore structure of natural bamboo and the outstanding photocatalytic activity of ZnO/WO3, we fabricated an efficient bamboo-based photocatalyst (ZnO/WO3@bamboo) for the efficient photocatalytic degradation of formaldehyde and organic dyes. The pretreatment of bamboo substrates with NaOH solution resulted in the formation of nucleation sites for ZnO/WO3 growth within bamboo cellulose channels. Subsequently, the as-prepared ZnO and WO3 were mixed in different mass ratios, and loaded on the pretreated bamboo substrates using the hydrothermal method. The results showed that the ZnO/WO3@bamboo had the effective function of photocatalytic degradation of formaldehyde gas and organic dyes. Moreover, the as-prepared ZnO/WO3@bamboo photocatalyst demonstrated superior recycling ability toward organic pollutants, which was described by photocatalytic degradation efficiency of formaldehyde gas more than 89% after 10 cycles, and organic dyes over 93% after 20 cycles. The coupling of ZnO and WO3 leads to electron delocalization, which caused the electron holes generated in the valence band (VB) of ZnO to delocalize to the VB of WO3, and reduced the recombination of electron-hole. Therefore, the photocatalytic degradation performance of the ZnO/WO3@bamboo was enhanced. The proposed ZnO/WO3@bamboo photocatalyst holds great promise in the field of air pollution and wastewater remediation.

Promoting propane dehydrogenation performance of Co/silicalite-1 catalysts

Co catalysts supported on silicalite-1 (S-1) zeolite are developed in this work for direct propane dehydrogenation to propylene (PDH), showing excellent activity and propylene selectivity. Comprehensive characterizations of XRD, SEM, N2-sorption, TEM, DR UV–vis, H2-TPR, and TGA jointly evidence that the atomic-level dispersed CoOx species have significantly positive influence on the catalytic performance for PDH reaction. Alkaline treatment is a kind of advanced and effective method to create a number of defects on S-1 support, further isolating CoOx species and thus depressing side reactions. After the optimizing treatment on support, the catalyst with 0.5 wt% of Co supported on the S-1 pretreated with 0.1 mol/L of NaOH solution can exhibit simultaneously 78 % of propane conversion and 97 % of propylene selectivity after 15-minute of induction period. This work confirms that the highly-dispersed CoOx species bonded to zeolite are necessary for obtaining highly active and selective Co sites confined in the developed oxygen defects for the PDH reaction possibly due to the interface-induced effect between Co-O, and the main deactivation cause is ascribed to the migration and aggregation of Co sites in defects which points out that the direction for developing commercial Co based catalysts should focus on the stability design of active single Co atoms.

Cu/Cu2O/C nanoparticles and MXene based composite for non-enzymatic glucose sensors

Copper/Cuprous oxide/Carbon nanoparticles decorated MXene composite was prepared and subsequently examined for its potential application as a non-enzymatic glucose sensor. To carry out this, initially the Cu MOF/MXene composite was synthesised by the hydrothermal method and was annealed in an unreacted environment at different time intervals. During this process, petal like Cu MOF on MXene loses the organic ligands to form a Cu/Cu2O/C based nanoparticles on MXene. Further, an electrode was fabricated with the developed material for understanding the sensing performance by cyclic voltammetry and chronoamperometry in 0.1 M NaOH solution. Results reveal that the highest weight percentage of copper oxide in the composite (15 min of annealed material) shows a higher electro catalytic activity for sensing glucose molecules due to more active sites with good electron transfer ability in the composite. The formed composite exhibits a wide linear range of 0.001–26.5 mM, with a sensitivity of 762.53 μAmM−1cm−2 (0.001–10.1 mM), and 397.18 μAmM−1cm−2 (11.2–26.9 mM) and the limit of detection was 0.103 μM. In addition to this, the prepared electrode shows a good reusability, repeatability, selectivity with other interferences, stability (93.65% after 30 days of storage), and feasibility of measuring glucose in real samples. This finding reveals that the metal oxide derived from MOF based nanoparticle on the MXene surface will promote the use of non-enzymatic glucose sensors.

Enzyme-free magnetic relaxation detection for glucose based on the Mn(IV)/Mn(II) conversion under alkaline condition

Herein, we have developed two enzyme-free magnetic relaxation assays for the detection of glucose utilizing the principle that glucose reduces Mn(IV) species to Mn(OH)2 in an alkaline environment, and the further conversion of Mn(OH)2 to Mn2+ under neutral condition can induce a noteworthy increase in the transverse relaxation rate (1/T2) of water protons. Thus, MnO2 nanosheets were first employed as probes and signaling units for the magnetic relaxation detection of glucose, achieving a detection limit of 1 μM. Furthermore, we realized straightforward magnetic relaxation detection of glucose by direct mixing of Mn2+ ions, NaOH and glucose in solution. This process encompasses the in-situ oxidation of Mn2+ ions to MnO(OH)2 and the subsequent reduction of MnO(OH)2 by glucose to Mn(OH)2, thereby integrating probe synthesis, and target identification within a one-pot reaction. To our knowledge, this type of analysis is more superior compared with the approach utilizing MnO2 nanosheets, since it exhibits higher sensitivity (with a limit of detection at 0.6 μM), faster, and enhanced convenience. Considering the advantages of being enzyme-free and facile, the magnetic relaxation sensing strategy, grounded in the redox reaction of Mn(IV) and glucose, holds substantial potential for diverse applications.

Effect of NaOH Concentration on Rapidly Quenched Cu–Al Alloy-Derived Cu Catalyst for CO2 Hydrogenation to CH3OH

By utilizing greenhouse gas CO2 and renewable energy-sourced H2 to produce methanol, the “methanol economy” can replace fossil fuels and H2 as the energy storage medium, which not only reduces CO2 emissions, but also mitigates the energy shortage issue. However, the traditional Cu-based catalysts for CO2-to-methanol conversion suffer from low activity at low temperature and high vulnerability to sintering and deactivation. In this contribution, rapidly quenched skeletal Cu catalysts (RQ Cu) are prepared by leaching the RQ Cu–Al alloy with NaOH aqueous solutions of different concentrations. It is found that high NaOH concentration of 10 wt% favors the preparation of the RQ Cu-10 catalyst with higher porosity, lower residual Al content, and larger active Cu surface area (SCu) than the RQ Cu-3 catalyst leached with 3 wt% of NaOH solution. However, in aqueous-phase CO2 hydrogenation at 473 K and 4.0 MPa, the CO2 conversion over the RQ Cu-3 catalyst is more than two times greater than that over the RQ Cu-10 catalyst, and the selectivity and productivity of methanol are 1.20 and 2.69 times of the corresponding values over the RQ Cu-10 catalyst. At 5.0 MPa, the selectivity and productivity of methanol are further boosted to 97.9% and 1.329 mmol gCu–1 h–1 on the RQ Cu-3 catalyst. It is identified that the SCu of the RQ Cu-3 catalyst is well preserved after reaction, while dramatic growth of the Cu crystallites occurs for the RQ Cu-10 catalyst. The better catalytic performance and stability of the RQ Cu-3 catalyst are tentatively attributed to the presence of more residual Al species by using NaOH solution with lower concentration for Al leaching, which acts as the dispersant for the Cu crystallites during the reaction.

Elucidation of the optical, electronic, and photoelectrochemical properties of p-type CuFe2O4 photocathodes

High-quality thin films of p-type CuFe2O4 photocathode were prepared for the first time on FTO-coated glass substrates by a novel nonaqueous solution using spray pyrolysis method. The films' critical physical and photophysical properties, including morphology, optical properties, carrier transport properties, band position, and photoelectrochemical (PEC) characteristics, were analyzed and estimated. The feasibility of PEC water splitting was systematically evaluated. The prepared reddish-brown CuFe2O4 film exhibits a compact and uniform morphology. Its optical bandgap is approximately 1.42 eV, and it possesses a suitable conduction band position, indicating its capability to facilitate solar-driven water splitting and absorb visible light. Under AM 1.5 simulated solar illumination, the photocurrent density of 12 μA/cm2 was attained in a 1 mol NaOH solution. However, the prepared CuFe2O4 films demonstrate instability under constant light in the electrolyte owing to the copper reduction reaction. These research results offer a fresh insight into the potential application of CuFe2O4 as a photocathode semiconductor in PEC water splitting.

Effect of chloride binding behavior of cement hydration products on chloride critical value of steel corrosion in the presence of Na+ and Ca2+

To accurately predict the service life of concrete structures, the effect of chloride binding behavior of cement hydration products on steel corrosion should be taken into account. In this study, the steel specimen with cement paste coating were prepared to investigate the effect of chloride binding behavior on steel initial corrosion in the presence of Na+ and Ca2+. The results show that the higher pH level and Ca2+ concentration effectively inhibited the leaching C–S–H, while the Ca2+ increased the Ca/Si ratio of C–S–H, thereby enhancing the physical chloride binding capacity of cement paste coating in the CaCl2-Ns system (the addition of CaCl2 in NaOH solution). This enhancement primarily accounted for the higher critical value (Ccrit) of 0.03 mol/L in the CaCl2-Ns system, surpassing that of specimens exposed to other corrosion solutions, which was 0.01 mol/L. Both chloride ions from NaCl and CaCl2 could partially replace carbonate ions in monocarboaluminate (Mc), indicating that the cation type did not exert significant influence on chemical binding in this study.

Six-membered ring-reinforced flexible high-elongation block polyamide as strong and multi-reusable hot melt adhesive

This study presented the synthesis and characterization of polyester block polyamide hot melt adhesives (PPHMAs) with high adhesion strength and toughness. The PPHMAs demonstrated an adhesion strength of 11.04 MPa and toughness of 22.54 MJ·m−3, making them suitable for various substrates such as aluminum, copper, and stainless steel. The polyamide segments synthesized from dimer acid and 2-methyl-1,5-diaminopentane exhibited characteristics of softness and high elongation. Using isophorone diamine as a reinforcing agent introduced a stable six-membered ring structure, which enhanced the polymer's rigidity and strength, thus meeting the requirements for polyamide segments to function as the hard segments in block polymers. A trace amount of Tris (2-aminoethyl) amine provided the cross-linking sites which are similar to those in neuronal structures. The polyester segments, which were synthesized from poly (propylene glycol) diglycidyl ether and sebacic acid, served as the soft segments in the block polymer and were connected to the hard segment via amide bonds. The addition of the polyester segments enhanced the non-covalent molecular interactions within PPHMAs, leading to dynamic crosslinking properties. The adhesive maintained stable adhesion even after six cycles, which showcased its durability. Furthermore, the PPHMAs exhibited notable chemical resistance. It retained over 60 % adhesion strength after exposure to some chemical solvents including artificial seawater, 5 % NaOH solution, 5 % HCl solution, and DMSO for 24 h. These findings offered a novel approach to enhancing the adhesion strength and toughness of conventional thermoplastic hot melt adhesives.

A dilute sodium hydroxide technique for radiolarian extraction from cherts

Radiolarians have been used to determine geological ages and have contributed markedly to our understanding of Earth’s history. Hydrofluoric acid (HF) has traditionally been used to extract radiolarian fossils from siliceous deposits (i.e., radiolarian cherts), but this acid is strictly regulated because of environmental and human health concerns. Here we report on the successful extraction of radiolarians from cherts using a low-concentration NaOH solution (1 mol/L NaOH) as an alternative to HF. The degree of chert dissolution in NaOH is strongly temperature-dependent and is limited at < 80 °C. However, even a 1 mol/L NaOH solution is sufficient to dissolve chert at 100 °C. Our new NaOH method yields better-preserved radiolarian fossils compared with the conventional HF method. The 1 mol/L NaOH solution is less hazardous, easier to handle, and has fewer effects on the environment and human health than HF. Therefore, this method can be widely used for research and teaching purposes in studies of radiolarian fossils, even in institutions where HF cannot be used owing to chemical restrictions.

Kinetics of Alkali-Silica Reaction: Application to Sandstone.

Despite extensive research, the relationship between the progression of the alkali-silica reaction (ASR) and the expansion of concrete due to ASR, particularly for the heterogeneous aggregate with slow reactivity, is not thoroughly understood. In this paper, the dissolution kinetics of reactive silica present in sandstone when exposed to NaOH solutions, alongside the expansion characteristics of rock prisms under ASR conditions, were studied. The experimental results indicate that ASR behaves as a first-order reaction, accompanied by an exponential decrease in the concentration of OH- over time, and the dissolution rate of silica is predominantly governed by diffusion dynamics. Notably, increasing the temperature accelerates ASR, which augments the expansive pressure in a confined and limited space, leading to more significant aggregate expansion. Conversely, higher temperatures also result in a diminished retention of ASR gels within the aggregate, leading to the mitigation of ASR expansion. Our findings underscore that larger aggregates retain a greater quantity of gels, resulting in more pronounced expansion. To establish an ASR prediction model based on the relationship of the ASR expansion of concrete to high and low temperatures, the parameters such as the range of curing temperatures and the grading size of aggregates should be carefully considered for the experiments.

MODIFICATION OF WOVEN DENDROCALAMUS ASPER IN COMPOSITE APPLICATIONS

The aim of this study is to examine the influence of immersing Petung Bamboo in a NaOH solution on the tensile strength (TS) of composites containing an epoxy matrix. Petung Bamboo Webbing was given 0%, 3%, 6% and 9%, soaking treatment. The Composite utilised in this investigation was fabricated by the Vacuum Assisted Resin Infusion technique. Tensile testing of composites is conducted according to the ASTM D638-1 standard. The findings indicated a positive correlation between the concentration of NaOH immersion and the adhesion between the woven surface of Petung Bamboo and the matrix. Consequently, the TS of the Composite was enhanced. However, increasing the concentrations beyond a certain point leads to more degradation of the lignin and cellulose in the fibers, resulting in a loss in the strength of the composite. The Petung Bamboo woven reinforced Composite achieved the highest TS of 136.06 MPa after being treated with a 6% NaOH immersion. This was followed by a 3% NaOH immersion treatment resulting in a TS of 106.04 MPa. Without any NaOH immersion treatment, the composite had a TS of 97.31 MPa. The lowest TS of the composite was observed after a 9% NaOH immersion treatment, measuring 90.79 MPa. The Petung Bamboo wicker-reinforced composite with NaOH immersion treatment showed higher fiber pullout and fiber-matrix debonding failures, while higher NaOH treatment concentration reduced these failures.

Relationship between calcium forms and organic carbon content in aggregates of calcareous soils in northern China

The agricultural soil organic carbon (SOC) pool is one of the most active C pools in terrestrial ecosystems, and soil aggregates are the main site of SOC fixation. Mineral sorption plays a crucial role in SOC accumulation. Calcium (Ca) is a typical soil mineral element that plays a crucial role in SOC accumulation and is fundamental for the formation of soil aggregates. Although Ca has been shown to regulate the stability of SOC, the relationship between different forms of Ca and SOC within aggregates in northern China remains unclear. In this study, we selected five soils (black soil, light chernozem soil, fluvo-aquic soil, sierozem soil, and loess soil) with different calcium carbonate (CaCO3) contents as the target materials. Water-stable aggregates were separated using the wet-sieving method. Soil respiration was measured using the static alkali absorption method (carbon dioxide [CO2] absorption by NaOH solution). The CaCO3 content was quantified using the CO2 gas volume method, and the continuous leaching method was used to analyze the different forms of Ca (water soluble-Ca, exchangeable-Ca, acid soluble-Ca, and bound to organic-Ca). In-situ field sampling was used to reveal the associations between different forms of Ca and SOC within aggregates. The results showed that besides the CaCO3 form, exchangeable-Ca (20.06 %–57.86 %) and bound to organic-Ca (26.69 %–73.91 %) were major Ca forms in calcareous soils. There was a nonsignificant negative correlation between CaCO3, acid soluble-Ca, and exchangeable-Ca and SOC in the bulk soil. However, there was a significant negative correlation among CaCO3, acid soluble-Ca, and exchangeable-Ca with SOC in macro-aggregates (> 0.25 mm) and micro-aggregates (0.25–0.053 mm). A 90-day incubation experiment was conducted to verify the previous speculations, which revealed that CaCO3 increased SOC mineralization and reduced the content of SOC, while enhancing the acid soluble-Ca and bound to organic-Ca content. In the treatment with added CaCO3, there was a negative correlation between acid soluble-Ca and bound to organic-Ca and SOC in bulk soil and macro-aggregates (> 0.25 mm). The effect of Ca2+ on SOC should not be ignored. Excessive Ca2+ may be converted into different forms of Ca to occupy the bonding sites for SOC on the surface of soil particles with silt and clay particles, forming a pseudo-aggregate structure, and the SOC traveling between soil particles, which is not conducive to SOC stabilization and accumulation.

Waste valorization: Sustainable geopolymer production using recycled glass and fly ash at ambient temperature

This research explores the reutilization of waste glass powder (GP) and class F fly ash (FA) in the development of an advanced geopolymer, focusing on reducing natural resource consumption to serve as a green alternative for conventional concrete material. Investigating mix ratios of GP-to-FA (0-to-1), activated with 2–12 M NaOH, followed by ambient temperature curing, this study mainly assesses strength (compressive, and flexural) and durability at different ages. Mechanical properties concerning reaction kinetics and Al/Si ratio, reveal that GP initially acts as an inert filler with slow reaction kinetics, while significant strength improvement at later ages is attributed to the reaction between GP and FA. Optimal performance is achieved with a geopolymer mixture featuring a GP-to-FA ratio of 1:3 (Al/Si ratio of 0.51) and an 8 M NaOH solution, resulting in the highest compressive strength of 40 MPa and superior durability. Microstructural analysis (SEM-EDS, and 29Si MAS NMR) identifies the reacting product as calcium/sodium aluminate silicate hydrate (C/N-(A)-S-H) gel within the geopolymer matrix. Leaching tests further underscore potential environmental concerns related to excessive alkali leaching, necessitating meticulous mix design management. Embodied energy and carbon footprint assessments confirm the environmental friendliness of the GP-FA-based geopolymer. Overall, this research demonstrates the feasibility of producing effective geopolymers from dry waste at ambient temperature, emphasizing the potential synergy between waste glass recycling and the concrete industry towards sustainable construction practices.

Simple and Fast Determination of Carbaryl Pesticide in Commercial Topical Formulations by Capillary Electrophoresis

A novel analytical method using capillary zone electrophoresis (CZE) for simple and fast determination of the pesticide carbaryl in commercial topical formulations was developed and validated. The carbaryl was previously hydrolyzed quantitatively under an alkaline medium (NaOH solution) to form 1-naphthol, which was separated and quantified by CZE with spectrophotometric detection at 214 nm. Optimization of the hydrolysis reaction regarding time and NaOH concentration was conducted. The CZE separation was achieved in less than 3 min using a bare silica capillary (60 cm total length) and a 10 mmol L-1 sodium borate buffer (pH 9.3) as background electrolyte. The proposed CZE method was linear in the 0.25 to 70 mg L-1 concentration range, as attested by a coefficient of determination (R2) higher than 0.999 and confirmed by the lack of fit test. Recovery tests at three concentration levels provided recovery percentages ranging from 80 to 115%, indicating acceptable accuracy. The limits of detection (LOD) and quantification (LOQ) were 0.08 and 0.25 mg L-1, respectively. The proposed CZE method was successfully applied for carbaryl determination in commercial samples of topical formulations such as powders and dry bath gel.

Electro-Reactivity of Resorcinol on Pt(111) Single-Crystal Plane and Its Influence on the Kinetics of Underpotentially Deposited Hydrogen and Hydrogen Evolution Reaction Processes in 0.1 M NaOH Solution

This article primarily presents cyclic voltammetry, Tafel polarization and ac. impedance spectroscopy electrochemical examinations of resorcinol (RC) electro-reactivity on the Pt(111) surface and its influence on the kinetics of UPD H (underpotentially deposited hydrogen) and the HER (hydrogen evolution reaction) in a 0.1 M NaOH supporting solution. The collected data provided evidence of the RC-ion’s surface adsorption and its further electroreduction in the presence of surface-adsorbed H radicals along with their primary beneficial role on the kinetics of the UPD H process. The above was elucidated through an evaluation of the associated charge-transfer resistance and capacitance parameters, and was carried out on the platinum (111) electrode plane, comparatively, for the RC-free and resorcinol-modified NaOH electrolyte. In addition, the recorded cathodic charge transients (obtained by injecting small amounts of RC-based 0.1 M NaOH solution to initially resorcinol-free electrolyte, carried out at the constant electrode potential characteristic to the UPD H potential zone) provided evidence that the RC species undergoes electrocatalytic reduction through the involvement of the Pt(111)-chemisorbed hydrogen radicals.

Optimizing crystal transitions in low-temperature, low-concentration NaOH solutions to prepare cellulose I and II composite materials

Optimizing crystal transitions in low-temperature, low-concentration NaOH solutions to prepare cellulose I and II composite materials

Application of Taguchi approach to optimize the waste glass powder in developing eco-friendly ternary blended aluminosilicate matrix

This study investigated the effects of incorporating varying proportions of waste glass powder (WGP) and fly ash (FA) on the strength characteristics of ternary blended ground granulated blast furnace slag (GGBS) based geopolymer matrix. The examination was conducted to explore the impact of different levels of substitution of WGP (ranging from 25 % to 40 %) and FA (ranging from 20 % to 35 %) in GGBS-based geopolymer concrete under conditions of ambient curing, employing Taguchi L16 optimization. An investigation into the influence of various input parameters on the compressive strength and workability results was carried out through the utilization of analysis of variance (ANOVA). The analysis based on signal to noise ratio (SNR) revealed that the most effective mix composition consisted of 30 % WGP, 20 % FA, 50 % GGBS, and an 8 M NaOH solution, yielding the highest compressive strength value of 48.3 MPa. Additionally, the examination of the microstructure and morphology of the geopolymer fragments was explored by utilizing scanning electron microscopy (SEM) in conjunction with energy dispersive spectroscopy (EDS), revealing the creation of a densely packed microstructure for the optimal blend.

Detecting structure and composition of passive film on Mo-containing stainless steel formed in alkaline environment by aberration-corrected TEM

In this paper, the structural and compositional evolution of the passive films formed on the Mo-containing stainless steels induced by chloride ions in 0.1 mol L−1 NaOH solution has been studied by means of aberration-corrected transmission electron microscopy and X-ray photoelectron spectroscopy. Mo is enriched at the outer layer of the passive film, which is attributed to the induction of Cl-. Moreover, MoO42- is formed due to the alkaline solution, which impedes the film formation process and inhibits the thickening of the film. Consequently, the positive effect of Mo in the passive film on the corrosion resistance is strongly suppressed.

Ultrasonic-assisted pulse electrodeposition process for producing nanocrystalline nickel films and their corrosion behavior: Competition between mass transport and nucleation

Ultrasonic-assisted pulse electrodeposition of nanocrystalline nickel (NC-Ni) coatings from Watts bath on copper substrate was investigated. Direct (DC), pulsed (PC), and pulse reversed (PRC) current electrodeposition techniques were employed to electrodeposit NC-Ni coatings in the absence and presence of ultrasound wave with a nominal power ranging from 95 W to 200 W and their surface morphology, hardness, and crystalline microstructure were compared. We observed that as the ultrasound power increases, the cathodic efficiency and the microhardness increase, whereas the crystallite size and surface roughness decrease for NC-Ni electrodeposited by the three techniques in the same way. However, the effect of pulse waveform is dominant. The finest crystallite size (24 nm) and highest hardness (585 HV) were achieved for NC Ni coatings PC electrodeposited using an ultrasound with 200 W nominal power. It is believed that the coating produced by PC and PRC techniques develops a preferential orientation in (111) and (100) planes, respectively. The application of ultrasound wave and increasing its nominal power changes the preferential orientation of all obtained coatings to (111) planes. The corrosion behavior of NC Ni coatings, as investigated by potentiodynamic polarization and electrochemical impedance spectroscopy in NaOH solution, demonstrates the effect of nanocrystalline on the passivation and corrosion resistance of NC-Ni coatings.