Electrocatalysis最新文献

Efficient and cost-effective electrolysis technique is prerequisite for industrial scale hydrogen production. This study demonstrates fabrication of electrochemical catalyst in the form of a composite structure generated through rapid oxidation using microwave (MW) of self-assembled IrO₂ nanoparticles on reduced graphene oxide (rGO). MW-IrO₂/rGO catalysts were synthesized using the microwave-assisted aqueous solution method, and its physical/chemical structure, morphology, and oxygen evolution reaction (OER) properties were evaluated depending on the power of microwave. The composite structure with rGO support and small particle size of IrO₂ allow homogeneous dispersion, and large adsorption area, which dramatically enhances the electron and proton transports. The increased electrochemical surface area resulted in excellent performance of OER. Moreover, this study suggests a simple catalyst preparation method, leading to acceleration of manufacturing speed and cost saving. Thus, this work provides new insights into a facile microwave-assisted rapid oxidation method for efficient electrochemical applications such as PEM electrolysis cells.

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A series of Pd/Fe₃O₄@S-rGO was synthesized under various deposition times of Pd and their catalytic activity was investigated in alkaline media via chronoamperometry (CA), cyclic voltammetry (CVs), and electrochemical impedance spectroscopy (EIS) for the methanol oxidation reaction. For the S source, sodium dodecylbenzene sulfonate (SDBS) was used to obtain ultrafine Fe₃O₄ particles and enhance the graphene layer properties. Through the characterization measurements, it is concluded that Pd was deposited successfully onto Fe₃O₄@S-rGO (S and Fe₃O₄ dual-doped reduced graphene oxide) with nanoscale cubic lattice nanostructure. In the presence of Fe₃O₄, the band gap of Pd₄₅₀/ITO decreased from 3.46 to 1.74 eV. The band gap of fabricated catalyzes changed with the deposition time of Pd. In addition, the synergistic effect between Pd and Fe₃O₄ enhances the catalytic activity of the electrode toward methanol oxidation when compared bulk Pd electrode. The Pd₄₅₀/Fe₃O₄@S-rGO electrocatalyst showed a current density of 22.3 mA cm⁻² at a scan rate of 30 mV s⁻¹ with remarkable long-term stability in 0.5 M methanol in 1 M NaOH. This value is 2.2 times higher than the Pt/C (10 mAcm⁻²) catalyst under the same conditions. With modifying Fe₃O₄ the Tafel slope of Pd₄₅₀/ITO decreased from 180 to 118 mVdec⁻¹.

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Heavy metals are serious inorganic pollutants that need to be monitored in the hydrosphere with simple and cheap methods. Herein, a new sensor was fabricated by modifying a carbon paste electrode with MgO/Fe₂O₃ nanocomposite for simple, rapid, accurate, and highly sensitive simultaneous determination of Cd (II) and Cu (II) using differential pulse anodic stripping voltammetry. The electrochemical behavior of the constructed sensor was examined, and all parameters were optimized including deposition potential, time, pH, and scan rate. For Cd (II) and Cu (II), the respective detection limits were determined to be 3.3 × 10⁻¹¹ M and 3.6 × 10⁻¹¹ M, and the respective quantification limits were 1.1 × 10⁻¹⁰ M and 1.2 × 10⁻¹⁰ M. The sensor estimated Cd (II) and Cu (II) in Nile river, tap, and bottled real water samples with high recoveries ranging from 99 to 117%.

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This work reports a simple, low-cost, and environmentally friendly method to synthesize Ni-Co alloy nanoparticles (Ni-CoNPs) onto a glassy carbon electrode, GCE, and its use towards the efficient urea electrooxidation in basic aqueous media. Ni-CoNPs were directly electrodeposited onto the GCE surface, GCE/Ni-CoNPs by a single potentiostatic step, from the leached liquor of the cathode powder of spent Ni-MH batteries using the reline deep eutectic solvent, DES, as leaching agent, and electrolytic bath. The GCE/Ni-CoNPs were immersed in a 1 M KOH, 0.33 M urea aqueous solution and used as anode for urea electrochemical oxidation. The mass activity of this electrode depicted a maximum value of 27,900 mAmg⁻¹ cm⁻² at ca 0.5 V vs. Ag/AgCl and a steady state mass activity of 1690 mAmg⁻¹ cm⁻² during the potentiodynamic and potentiostatic evaluation. The performance of the GCE/Ni-CoNPs electrode reported in this work is similar or better than other electrodes reported for this purpose using more sophisticated, time-consuming, and costly methods.

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Herein, cerium/cerium oxide nanoparticles have been decorated on reduced graphene oxide (Ce/CeO₂-rGO) for room temperature electrochemical determination of H₂S in 0.5 M KOH. There is a superior linear correlation between the peak current density and H₂S content in the tested range of 1–5 ppm. Moreover, comparison to other abundant gases such as CO₂ shows no response at the potential of H₂S oxidation, confirming no interference with H₂S detection. It also reveals that the Ce/CeO₂-rGO nanocomposite is a highly selective and sensitive system for the determination of H₂S gas. Ce/CeO₂-rGO synthesized by a simple chemical approach and further characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR), field emission-scanning electron microscopy (FE-SEM), coupled energy dispersive analysis of X-ray (EDAX), and BET-surface area measurement confirms the porosity of synthesized nanomaterials and homogeneous decoration of Ce/CeO₂ nanoparticles on rGO sheets. The electrochemical studies, i.e., linear sweep voltammetry (LSV), of Ce/CeO₂-rGO demonstrate the electrochemical H₂S sensing at room temperature and for lower gas concentration (1 ppm) detection. The sensing mechanism is believed to be based on the modulation of the current and applied potential path across the electron exchange between the cerium oxide and rGO sites when exposed to H₂S.

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One-pot synthesis of Ce/CeO₂-GO hybrid nanostructure is of immense significance for H₂S gas sensors. Here is a new superficial synthetic way intended for the synthesis of Ce/CeO₂-GO nanocomposites through the sol–gel technique. Herein, we depict that the consequential Ce/CeO₂ NPs decorated on graphene oxide sheet material can give competent electrocatalysts for the H₂S oxidation reaction in an alkaline condition. The current density of 5.9 mA/cm² on the tiny potential of 2.5 mV vs. SCE demonstrates huge catalytic bustle and stability.

The electro-oxidation of glycerol (EOG) has gained wide attention as an alternative to producing value-added chemicals for glycerol valorization. In this study, a multimetallic electrocatalyst containing copper (Cu), nickel (Ni), tin (Sn), and phosphorus (P) was supported on a carbon catalyzed substrate (CCS) using an electroless deposition technique and evaluated for EOG. The effect of the electroless deposition time (15, 30, and 45 min) was also studied. Characterization of the CuNiSnP/CCS electrocatalyst via X-ray diffraction, scanning electron microscopy, and inductively coupled plasma optical emission spectroscopy revealed the formation of a thin-film morphology containing Cu as the main species on the surface and covering the carbon substrate. The electrochemical performance evaluation showed that the electrocatalyst obtained after 30 min of electroless deposition produced the maximum current density (6.5 mA/cm²). The multimetallic composition of CuNiSnP/CCS provided better reaction performance than related tri- (CuNiP/CCS and NiSnP/CCS), bi- (NiP/CCS), and monometallic (Cu/CCS) composites according to the peak current densities for the forward (i_f) and backward (i_b) oxidation, the i_f/i_b ratio, and the onset potential. Furthermore, CuNiSnP/CCS exhibited more stable and stronger resistance to poisoning. Overall, this study demonstrates the potential of the new electrode material CuNiSnP/CCS as an effective electrocatalyst for EOG.

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A novel multilayer fiber mesh electrode was developed and manufactured at the pilot scale to treat ammonia nitrogen wastewater containing chlorine. The performance of the new electrode was investigated and evaluated in a lab-scale reactor and a pilot-scale reactor. The results of electrochemical characterization methods showed that the multilayer fiber mesh electrode had better performance than the plate electrode under the same conditions. Moreover, the ammonia removal efficiency with the multilayer fiber mesh electrode reached 100% in 30 min, which was five times that with the traditional plate electrode. The influences of different operating parameters, such as current density, pH value, and chloride ion concentration, were investigated in the lab-scale reactor. Interestingly, the ammonia removal efficiency in the reactor with the multilayer fiber mesh electrode was higher when the pH value was lower, which was totally different from the results using the plate electrode. The main reason for this phenomenon is that more active chlorine free radicals generated at low pH values can be effectively utilized in the through-flow reactor with the multilayer fiber mesh electrode. Furthermore, the current efficiency of the reaction and the anode efficiency of the electrode showed good performance. Furthermore, this configuration was effective in removing ammonia from real leachate in the pilot-scale test. The multilayer fiber mesh electrode in flow-through mode was shown to be a promising material for the treatment of ammonia nitrogen wastewater containing chloride ions.

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A novel electrochemical nanosensor was established for the simultaneous measurement of dopamine (DA) and acetaminophen (AC). The nanosensor was achieved by modification of carbon paste electrode (CPE) by Ag nanoparticle, polyoxometalate, reduced graphene oxide (Ag@POM@rGO), and ionic liquid (IL). The electrochemical behaviors of DA and AC were evaluated by Ag@POM@rGO-IL/CPE and various electrochemical methods. Design-Expert software by response surface methodology (RSM) approach was utilized to consider the interaction between the different factors. The best electrochemical response was attained with 0.01 g of IL and 0.04 g of Ag@POM@rGO in the modified electrode, phosphate buffer solution (0.1 M, pH 7.0), and a sweep rate of 0.07 V s⁻¹. In the optimum situation, the calibration curves for DA and AC were achieved in a square wave voltammetry (SWV) manner, and linear dynamic ranges (LDR) were obtained to be 0.05–115.04 µM and 0.1–137.90 µM for DA and AC, respectively. The limit of detection (LOD) was attained to be 17.0 for DA and 37.0 nM for AC. The Ag@POM@rGO-IL/CPE showed good stability, productivity and repeatability, and advanced recovery, and it has a little price and low background current. Also, the usage of this nanosensor was studied by measuring the DA and AC in the human plasma by means of worthy recovery. This technique is easy, rapid, and cheap and can be utilized as a significant device in the quantitative analysis of the medicinal product.

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Among various chalcogenide materials, transition metal sulfides are known to be effective catalysts for the electrochemical hydrogen evolution reaction (HER). In particular, Ni-Co-S is a promising material for the next generation of non-precious metal HER catalysts due to its excellent HER activity in neutral pH solutions. Ni-Co-S is also advantageous in large-scale applications, as it enables relatively simple catalytic synthesis through electrodeposition. In this study, we employed a new S precursor, 2,5-dimercapto-1,3,4-thiadiazole (DMTD), for the electrodeposition of Ni-Co-S, instead of the conventional S precursor, thiourea (TU). Ni-Co-S synthesized with DMTD (Ni-Co-S_DMTD) showed enhanced HER activity at neutral pH compared to that synthesized with TU (Ni-Co-S_TU). It has been found that this improvement in activity is due to the large surface area and high S content of Ni-Co-S_DMTD. The S content and HER activity of Ni-Co-S_DMTD depend on the concentration of DMTD. At the optimal DMTD concentration (12 mM), Ni-Co-S_DMTD exhibited an overpotential of 303 mV at a current density of 10 mA cm^− 2 and a Tafel slope of 99 mV dec^− 1 in a phosphate buffer solution (pH 7.4).

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