Enhanced Corrosion Inhibition of Q235 Steel by N,S Co-Doped Carbon Dots: A Sustainable Approach for Industrial Pickling Corrosion Inhibitors.

A high yield of environmentally friendly N,S-codoped (N,S-CDs) and N-doping carbon points (N-CDs) carbon dots was achieved through a biochemical oxidation reaction at room temperature in this study. Acetaldehyde, sodium hydroxide, benzotriazole (BTA), and 2-mercaptobenzimidazole (MB) with a similar structure were used as raw materials. The microstructure and properties of the corrosion inhibitor for Q235 steel were evaluated by various experiments. The results demonstrated enhanced corrosion inhibition rates of the N,S-CDs compared to the N-CDs using electrochemical tests (93.83% vs 77.65%) and weight loss experiments (96.35% vs 91.65%) at 50 mg/L, respectively, compared to the blank material, indicating that N,S codoping can significantly improve the corrosion inhibition effect of carbon dots. The significant improvements were attributed to the formation of dense adsorption films and the hydrophobic properties of N and S-CDs nanoparticles on the steel surface, leading to an effective barrier against corrosion. The findings from this study provide important experimental data for potential industrial applications and hold important practical value in the field of pickling corrosion inhibitors.

One-Pot Hydrothermal Synthesized Nitrogen and Sulfur Codoped Carbon Dots for Acid Corrosion Inhibition of Q235 Steel.

N and S codoped carbon dots having good water solubility have been successfully made by a novel hydrothermal method and characterized by FTIR, XPS, and TEM. The as-synthesized CDs were carbon particles rich in polar functional groups less than 10 nm in size. Electrochemical measurements, gravimetry, and surface analysis methods were utilized to examine the inhibition characteristics and adsorption mechanism of CDs on the carbon steel in acid pickling solutions. Electrochemical measurements verified that the CDs displayed adequate protection with high inhibition efficiency of 97.8%. The long-term weight-loss experiments up to 72 h further confirmed the excellent corrosion inhibition at room temperature and 313 K. The results presented are helpful for the formulation of more effective acid pickling corrosion inhibitors.

A fast and high-efficiency electrochemical exfoliation strategy towards antimonene/carbon composites for selective lubrication and sodium-ion storage applications.

Two-dimensional (2D) layered antimony (Sb) materials are of importance due to their unique physicochemical properties, and they can be easily electrochemically exfoliated from bulk Sb in Na2SO4 electrolyte solution. However, the exfoliation yield is quite low and the exfoliated products are easily oxidized to Sb2O3, which prohibits their practical engineering applications. Herein, an antimonene/carbon composite is successfully fabricated with a high exfoliation yield through electrochemical exfoliation of bulk antimony chunk in a mixed electrolyte solution consisting of Na2SO4 and ethylene glycol. When the as-fabricated antimonene/carbon composite is added into PAO6 oil, the lubrication system exhibits a selective lubrication performance when sliding against GCr15 and YG8 ball, and the antiwear enhancement can be further improved by sliding against a YG8 ball. Besides, the antimonene/carbon composite can provide reliability and enough ion corridors during the charge/discharge processes. When tested as an anodic material for sodium-ion batteries, it exhibits a large capacity of 485.0 mA h g-1 at a current density of 200 mA g-1 after 150 cycles and a remarkable rate capability (334.5 mA h g-1 at 5 A g-1).

Insights into the newly synthesized N-doped carbon dots for Q235 steel corrosion retardation in acidizing media: A detailed multidimensional study.

N-doped carbon quantum dots (NCQDs) were synthesized by a hydrothermal method using folic acid and o-phenylenediamine as precursors. The inhibition behaviour of the NCQDs on Q235 steel in 1 M HCl solution was appraised through electrochemical impedance spectroscopy (EIS), potentiodynamic polarization curves (PDP), and surface analysis. The results demonstrated that the synthesized NCQDs had an effective anticorrosion effect on Q235 steel, and the corrosion inhibition efficiency of 150 mg/L NCQDs reached 95.4%. Additionally, the analysis of the PDP corrosion potential changes indicated that the NCQDs acted as a mixed corrosion inhibitor. Moreover, the NCQDs adsorbed onto the surface of steel by coordinating its electron-rich atoms with the iron metal to form a protective film, which slowed the dissolution reaction of the anodic metal to achieve corrosion inhibition. The adsorption mechanism of the NCQDs was consistent with Langmuir adsorption, including physical and chemical adsorption. Therefore, this work can inspire and facilitate, to a certain extent, the future application of doped carbon quantum dots as efficient corrosion inhibitors in pickling solutions.

Synthesis and Structure of Water-Soluble Sb Quantum Dots and Enhanced Corrosion Inhibition Performance and Mechanisms.

Generally, single organic or inorganic inhibitors could effectively inhibit corrosion for metallic materials; however, there are rarely reports about the hybrid corrosion inhibitors consisting of organic and inorganic inhibitors. Thus, in this work, we synthesize a hybrid environment-friendly water-soluble corrosion inhibitor (Sb quantum dots) containing Sb, Sb2O3, Sb2O4, and carbon using the electrochemical exfoliation method. The inhibition effectiveness in short- and long-term immersion tests is measured using electrochemical methods, weight loss, and surface analysis. The results exhibit that the corrosion inhibition efficiency sensitively relates to the concentration of Sb quantum dots (SQDs), which achieves the largest value as the concentration of SQDs increases to 200 mg/L. Atomic force microscopy, scanning electron microscopy, and contact angle analysis reveal that the SQDs well-disperse on and cover the Q235 steel surface at 200 mg/L. According to the Langmuir adsorption data, the physicochemical adsorption and effective antioxidation of SQDs on the passivated Q235 steel surface are in charge of the effective corrosion inhibition efficiency in 0.5 M H2SO4 solution.

The Unusual Tribological Properties of Graphene/Antimonene Heterojunctions: A First-Principles Investigation.

The extremely low friction between incommensurate two-dimensional (2D) materials has drawn more attention in the recent years. Structural superlubricity is a fascinating tribological phenomenon that is achieved in 2D heterojunctions despite the aligned or misaligned contacts that occur due to the disappearance of the lateral interactions between two incommensurate contacting surfaces. In this study, using the first-principles method, we report the computational realization of structural superlubricity for graphene/antimonene heterojunctions at the nanoscale. The calculated results clearly demonstrate that structural superlubricity between graphene and antimonene monolayers could be achieved under the misaligned contacts. The structural superlubricity is mainly attributed to lower work of separation, which maintains superlow friction coefficients.

In Situ Friction-Induced Graphene Originating from Methanol at the Sliding Interface between the WC Self-Mated Tribo-Pair and Its Tribological Performance.

Alcohols are reported to have superlubricity at low loads during sliding; however, their lubricity under high loads has rarely been reported. Meanwhile, the lubrication mechanism of alcohols under high loads is still not well understood. Here, we first report the lubricity of methanol under 98 N and 1450 rpm and demonstrate the formation of graphene and fullerene-like nanostructures induced by tribochemical reactions. Results show that the lubrication mechanism was mainly attributed to the friction-induced graphene under boundary lubrication condition. Besides that, the wear rate of a YG8 hard alloy ball mainly occurred at the run-in processes, and the friction-induced graphene effectively inhibited further wear after the run-in processes. The formation mechanism of graphene was well investigated, and the flash temperature rise and catalyst (WC, WO2, and WO3) were the major causes for the formation of graphene.

Efficient adsorption of benzoic acid from aqueous solution by nitrogen-containing activated carbon.

Adsorption is an efficient treatment process to remove benzoic acid from aqueous solution. In this study, nitrogen-containing surface groups were introduced onto activated carbon (AC) surface by modification with ammonium hydroxide, ammonium carbonate, melamine or urea. The nitrogen-containing AC samples were characterized using N2 adsorption-desorption, Boehm titration, determination of the pH of the point of zero charge (pHpzc) and X-ray photoelectron spectroscopy. The adsorption of benzoic acid from aqueous solution by nitrogen-containing AC has been studied. The Langmuir model fitted the experimental data of equilibrium isotherms better than the Freundlich model. At initial solution pH 2.1, the adsorption capacity was closely related with the amount of pyridinic and pyrrolic N on the AC surface, which indicated these two nitrogen-containing groups played an important part in the adsorption process. The enhancement of adsorption capacity was due to the strengthened π-π dispersion force between benzoic acid and the AC basal plane. Since the surface charge of AC as well as the existence form of benzoic acid varied with solution pH value, the adsorption capacity was found to be highest at pH 3.8 and dropped sharply at higher or lower pH values.

Five-partite entanglement generation between two optical frequency combs in a quasi-periodic χ (2) nonlinear optical crystal.

We theoretically prove five-partite entanglement can be produced among modes of two simultaneously generated optical frequency combs via second-order nonlinear interaction in a designed periodically poled lithium niobat (PPLN) crystal. An extendible model is proposed to analyze the entanglement characteristics of generated comb modes by applying van Loock and Furusawa criteria. Our proposal provides a potential approach for generating multipartite entangled states, the so-called cluster states, which are the key resources for quantum computation. Moreover, simultaneously generation of two entangled combs can provide much higher efficiency to generate cluster states.

A near-wearless and extremely long lifetime amorphous carbon film under high vacuum.

Prolonging wear life of amorphous carbon films under vacuum was an enormous challenge. In this work, we firstly reported that amorphous carbon film as a lubricant layer containing hydrogen, oxygen, fluorine and silicon (a-C:H:O:F:Si) exhibited low friction (~0.1), ultra-low wear rate (9.0 × 10(-13) mm(3) N(-1) mm(-1)) and ultra-long wear life (>2 × 10(6) cycles) under high vacuum. We systematically examined microstructure and composition of transfer film for understanding of the underlying frictional mechanism, which suggested that the extraordinarily excellent tribological properties were attributed to the thermodynamically and structurally stable FeF2 nanocrystallites corroborated using first-principles calculations, which were induced by the tribochemical reaction.

Probing the intrinsic failure mechanism of fluorinated amorphous carbon film based on the first-principles calculations.

Fluorinated amorphous carbon films exhibit superlow friction under vacuum, but are prone to catastrophic failure. Thus far, the intrinsic failure mechanism remains unclear. A prevailing view is that the failure of amorphous carbon film results from the plastic deformation of substrates or strong adhesion between two contacted surfaces. In this paper, using first-principles and molecular dynamics methodology, combining with compressive stress-strain relation, we firstly demonstrate that the plastic deformation induces graphitization resulting in strong adhesion between two contacted surfaces under vacuum, which directly corresponds to the cause of the failure of the films. In addition, sliding contact experiments are conducted to study tribological properties of iron and fluorinated amorphous carbon surfaces under vacuum. The results show that the failure of the film is directly attributed to strong adhesion resulting from high degree of graphitization of the film, which are consistent with the calculated results.