Nitrogen-doped carbon dots as high-effective inhibitors for carbon steel in acidic medium

Facile Fabrication of Highly Fluorescent N-Doped Carbon Quantum Dots Using an Ultrasonic-Assisted Hydrothermal Method: Optical Properties and Cell Imaging

“…The three representative peaks at 284.7, 531.6, and 399.6 eV in the XPS full spectrum of N-CQDs-1 (Figure 4A) correspond to C 1s, O 1s, and N 1s, respectively; the high-resolution XPS spectrum of C 1s (Figure 4B) exhibits four peaks at 284.7, 286.0, 288.0, and 288.9 eV, corresponding to the CC/C−C, C−N, C−O/C−O−C, and CO groups, respectively; 49,50 the O 1s spectrum of N-CQDs-1 (Figure 4C) presents two peaks at 530.6 and 531.8 eV assigned to the C O and the C−OH/C−O−C groups; 51,52 and the N 1s spectrum of N-CQDs-1 (Figure 4D) depicts two peaks at 399.6 and 401.1 eV, attributed to C−N−C and N−H, respectively. 38,53 The full spectrum of N-CQDs-2 presented in Figure 5A 38,49−53 Comparing the XPS results of the two CQDs, most of the functional groups are similar. The above results indicate that N has been successfully doped into the structure of CDs, and the CQDs were coated with oxygencontaining functional groups, such as carboxylic, hydroxyl, carbonyl, and epoxy groups, which facilitate their hydrophilicity and dispersity in water.…”

“…To study the surface chemistry of the CQDs, X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FTIR) spectroscopy were carried out. The three representative peaks at 284.7, 531.6, and 399.6 eV in the XPS full spectrum of N-CQDs-1 (Figure A) correspond to C 1s, O 1s, and N 1s, respectively; the high-resolution XPS spectrum of C 1s (Figure B) exhibits four peaks at 284.7, 286.0, 288.0, and 288.9 eV, corresponding to the CC/C–C, C–N, C–O/C–O–C, and CO groups, respectively; , the O 1s spectrum of N-CQDs-1 (Figure C) presents two peaks at 530.6 and 531.8 eV assigned to the CO and the C–OH/C–O–C groups; , and the N 1s spectrum of N-CQDs-1 (Figure D) depicts two peaks at 399.6 and 401.1 eV, attributed to C–N–C and N–H, respectively. , The full spectrum of N-CQDs-2 presented in Figure A is similar to that of N-CQDs-1, showing three typical peaks: C 1s (284.8 eV), N 1s (399.5 eV), and O 1s (531.3 eV); the high-resolution XPS spectrum of C 1s (Figure B) indicates that CC/C–C (284.7 eV), C–N (286.0 eV), C–O/C–O–C (288.0 eV), and CO (288.9 eV) groups exist in N-CQDs-2; the O 1s spectrum (Figure C) of N-CQDs-2 shows the presence of CO (529.6 eV) and C–OH/C–O–C (531.3 eV) groups in N-CQDs-2; and the high-resolution N 1s spectra (Figure D) of N-CQDs-2 shows that N exists in the form of C–N–C (399.5 eV) and N–H (401.2 eV) in N-CQDs-2. ,− Comparing the XPS results of the two CQDs, most of the functional groups are similar. The above results indicate that N has been successfully doped into the structure of CDs, and the CQDs were coated with oxygen-containing functional groups, such as carboxylic, hydroxyl, carbonyl, and epoxy groups, which facilitate their hydrophilicity and dispersity in water.…”

“…Hydrothermal, microwave, or ultrasound approaches are promising to solve the above problems. For example, Cao et al 38 synthesized nitrogen-doped CQDs by hydrothermal treatment of citric acid and urea for effectively inhibiting the corrosion of carbon steel. Holáet al 39 prepared full-color fluorescent CDs by simple solvothermal decomposition in formamide using urea and citric acid as raw materials, confirming that N-doped CDs are useful for regulating CD emission.…”

Performance Evaluation of New Chalcone Oxime Functionalized Graphene Oxide as a Corrosion Inhibitor for Carbon Steel in a Hydrochloric Acid Solution

“…This behavior is exhibited at all frequencies and represents the most effective inhibitory impact of CO-GO on the metal substrates examined. EIS parameters such as solution resistance ( R s ), polarization resistance ( R p ), phase shift ( n ), double-layer capacitance ( C dl ), and percentage of inhibition performance were calculated using an equivalent circuit shown in Table and Figure c. − The constant phase element (CPE) was utilized to properly represent the electrode/solution contact. The CPE impedance ( Z CPE ) is provided by where Q is the proportionality factor, j is the imaginary unit, ω is the radian frequency, and n (0 < n < 1) is the CPE exponent, which describes an ideal capacitor in the case of n = 1 and a pure resistor in the case of n = 0.…”

Application of Carbon Dots as Corrosion Inhibitor: A Systematic Literature Review

“…N-CQDs based-corrosion inhibitor has good performance at room temperature and higher temperatures. The other nitrogen-doped carbon dots (N-CDs) have been synthesized with 4-aminosalicylic acid as a precursor through the solvothermal method [40] and a combination of citric acid and urea as precursors through the hydrothermal method [51]. N-CDs from 4-aminosalicylic acid approximately have average sizes and heights of 3 nm and 2-4 nm, respectively, whereas N-CDs from citric acid and urea have a spherical form with an average size of 10-14 nm.…”