Electrocatalytic oxidation of phenol from wastewater using Ti/SnO2–Sb2O4 electrode: chemical reaction pathway study

Abstract In this study, a titanium plate was impregnated with SnO2 and Sb (Ti/SnO2–Sb2O4) for the electrocatalytic removal of phenol from wastewater, and the chemical degradation pathway was presented. The effects of various parameters such as pH, current density, supporting electrolyte, and initial phenol concentration were studied. At optimum conditions, it was found that phenol was quickly oxidized into benzoquinone because of the formation of various strong radicals during electrolysis by the Ti/SnO2–Sb2O4 anode from 100 to <1 mg/L over 1 h. The results of GC/MS analysis showed the presence of some esters of organic acid such as oxalic acid and formic acid. HPLC analysis showed only trace amounts of benzoquinone remaining in the solution. The efficiency of TOC removal at the Ti/SnO2–Sb2O4 anode surface showed a degradation rate of 49 % over 2 h. Results showed that the molecular oxygen potential at the electrode was 1.7 V. The phenol removal mechanism at the surface of the Ti/SnO2– Sb2O4 anode was influenced by the pH. Under acidic conditions, the mechanism of electron transfer occurred directly, whereas under alkaline conditions, the mechanism can be indirect. This research shows that the proposed electrolyte can significantly influence the efficiency of phenol removal. It can be concluded that the treatment using an appropriate Ti/SnO2– Sb2O4 electrode surface can result in the rapid oxidation of organic pollutants

Properties of TiC Coating by Pulsed DC PACVD

In the PACVD technique, temperature and gas flow rate are two important parameters affecting the coating characteristics. Effect of these parameters on mechanical behaviors of TiC coating that was deposited on hot work tool steel (H13) was investigated in this paper. We analyzed TiC coating composition and structure with grazing incidence X-ray diffraction (GIXRD) and Fourier transformation infrared spectroscopy (FTIR). The mechanical properties of the coatings, such as microhardness, wear resistance, and surface roughness, were studied with Knoop hardness indentation, pin on disk wear tests, and atomic force microscopy, respectively. When the deposition temperature decreased from 490°C to 450°C and the CH4 to TiCl4 flow rate ratio was also increased from 1.5 to 6, TiC coating color changed from dark gray to silver. The best mechanical properties such as a high hardness (27 GPa), wear resistance, and low surface roughness were related to the coating that was deposited at 450°C

STUDY OF PULSE ON PULSED NANOCRYSTALLINE PLASMA ELECTROLYTIC CARBONITRIDING ON THE NANOSTRUCTURE OF COMPOUND LAYER

Surface hardening of commercially pure titanium by using pulse on pulsed nanocrystalline plasma electrolytic carbonitriding has been studied in this investigation. Coating process has been performed on Triethanolamine-based electrolyte by cooling bath. Nanostructure of obtained compound layer was examined with figure analysis of SEM nanographs. The effects of process variables, i.e., Triethanolamine concentration, electrical conductivity of electrolyte, applied voltage, and treatment time, have been experimentally studied. Statistical methods were used to achieve the optimum size of nanocrystals. Finally the contribution percentage of effective factors of pulsed current was revealed and confirmation run show the validity of obtained results.Pulse on pulse method, nanocrystalline, nanostructure, pulsed nanocrystalline plasma electrolytic carbonitriding

Electrochemical Corrosion of Oxidized Gamma TitaniumAluminide in Ringer's Solution: Electrochemical corrosion of oxidized gamma titanium aluminide

Ɣ-TiAl intermetallic alloy have a good potential for use as biomaterial, due to its good corrosion resistance. In this paper, two fundamental electrochemical techniques namely electrochemical impedance spectroscopy and potentiodynamic anodic polarization were used to evaluate the corrosion performance of Ɣ-TiAl in Ringer's solution. Surface modification treatments were employed with the purpose of improving corrosion resistance. The samples were oxidized at 550 °C in air for 1h. The results show that oxidized Ti-47Al-2Cr has much better corrosion resistant in Ringer’s solution. The presence of the oxide layer formed with the surface treatments increased their corrosion resistance. The low values of corrosion rate, and the high values for corrosion potential (Ecorr) and polarization resistance (Rp)obtained experimentally implies that Ɣ-TiAl can be competitively considered as analternative metallic biomaterial

Electrodeposited Ni-Co-P hierarchical nanostructure as a cost-effective and durable electrocatalyst with superior activity for bifunctional water splitting

Designing earth-abundant, cost-effective catalysts with superior performance for electrochemical water splitting is among the essential global challenges. In this study, amorphous Ni[sbnd]Co[sbnd]P coatings are applied on nickel nanocones array using the cyclic voltammetry electrodeposition method in different cycles and nickel-to-cobalt ratios. The electrocatalytic activities of the as-fabricated electrodes are studied for hydrogen evolution reaction and oxygen evolution reaction in alkaline and neutral solution. The three-dimensional nickel nanocones expose more active surface area for hydrogen evolution reaction and oxygen evolution reaction. Binder-free Ni[sbnd]Co[sbnd]P@nickel nanocones electrode exhibits superior hydrogen evolution reaction catalytic activity in the alkaline solution, which requires only 51 and 110 mV for delivering 10 and 100 mAcm −2 , respectively. Also, this electrode exhibits low oxygen evolution reaction overpotential of 221 mV and 254 mV at 10 and 100 mAcm −2 , respectively. The fabricated electrode is able to sustain the current density of 100 mAcm -2 with negligible degradation in overpotential which shows remarkable electrochemical stability. Moreover, this active and stable bifunctional electrocatalyst is used for full water splitting, able to deliver the current density of 10 mAcm −2 in 1.53 V. Also, the fabricated electrode represented favorable behaviors as electrocatalyst for both HER and OER in neutral solution. © 2019 Elsevier B.V.1

Highly Active and Durable NiCoSeP Nanostructured Electrocatalyst for Large-Current-Density Hydrogen Production

Large-scale hydrogen production via electrochemical water splitting requires low-cost and efficient electrocatalysts that work well at high current densities with a low overpotential for the hydrogen evolution reaction (HER). Herein, we report the production of a NiCoSeP nanostructured electrocatalyst by a low-cost, one-step electrodeposition technique. The catalyst exhibits very high current densities at small overpotentials (100 mA cm-2 at 151 mV, 500 mA cm-2 at 286 mV, and 1000 mA cm-2 at 381 mV) in 1.0 M KOH electrolyte. Moreover, NiCoSeP shows excellent HER performance in an acidic medium with small overpotentials of 93 and 131 mV to deliver large current densities of 100 and 500 mA cm-2, respectively. The unique morphology of NiCoSeP, superhydrophilic, and superaerophobic properties could facilitate electrolyte diffusion and rapid delivery of the generated bubble, respectively. Our experimental data confirm that the advantages of the excellent HER activity and stability of NiCoSeP nanostructure originate from the high active surface area, bimetal double-anion effect, and enhanced mass transfer of reactants and hydrogen bubbles. This work may provide a promising way for rational design and simplify the synthesis process of practical electrocatalysts. © 2021 American Chemical Society. All rights reserved.1