Papers by Keyword: Electrocatalysis

Abstract: Pd is one of the most promising catalysts for carbon dioxide electroreduction (CO₂RR) to formate (HCOO-). However, the lack of understanding of the active phase remains remains obscure with the role of different crystal facets in the formation of formic acid. Herein, Pd nanocubes and nanooctahedra particles with Pd (100) and (111) facets were, respectively, prepared. Compared with ordinary Pd nanoparticles and Pd octahedra, Pd nanocubes exhibited the most excellent electrocatalytic performance of carbon dioxide reduction, achieving a Faraday efficiency of 96% for formate production at a low applied potential of-0.20 V (vs RHE) in 0.5 M KHCO₃. At the same time, first-principles theoretical calculations also showed that the Pd (100) surface is more conducive to the conversion of CO₂ to HCOO* intermediates, thereby promoting the formation of formic acid. This result indicates that the Pd (100) crystal plane is more conducive to the reduction of CO₂ to formate. This research has important guiding significance for exploring the efficient reduction of carbon dioxide to formic acid catalyst.

Abstract: In this study, commercially available bare stainless steel 304 was investigated as a working electrode in urea electrooxidation in alkaline solution using different electrochemical techniques like cyclic voltammetry (CV) and linear sweep voltammetry (LSV). The electrode stability was also investigated by the constant potential electrolysis test. Different concentrations of KOH (0.5-4 M) were employed to study the electrooxidation of urea solution with concentration of 0.33 M. An anodic peak current density of 34.82mA/cm² was obtained at 473 mV versus Ag/AgCl reference electrode in urea solution at KOH concentration of 4 M. Stainless steel properties such as corrosion resistance, low cost in addition to its catalytic activity make it an ideal anodic electrocatalyst for electrooxidation of urea-rich wastewater.

Abstract: Acetylcholine (ACh) is a main neurotransmitter functioning in smooth muscle and cardiovascular system control. It also plays a key role in memory and learning. While excessive acetylcholine level results in decreased heart rates, depleted level of acetylcholine in human brains can lead to Alzheimer disease. Therefore, detection of acetylcholine is clinically vital. This study aimed at examining potential usage of titanium dioxide (TiO₂) doped with 2.5 mol% Zn as electrochemical sensors for acetylcholine detection. Zn-doped TiO₂ powder was synthesized by a solution combustion technique. Phase identification, microstructural examination, as well as electrocatalytic activity evaluation of the synthesized powder were conducted. The synthesized powder showed anatase phase with fine particle sizes ranging from 9.3 to 11.4 nanometers on average. Specific surface area of 75.48 m²/g was observed. Electrocatalytic activities of the powder in cholin acetate solutions with concentrations ranging from 0.05 to 0.1 μM and 1 to 10 μM were evaluated via cyclic voltammetry technique. At applied voltage of 0.05 V, peak currents corresponding to oxidation reactions between ACh and Zn-doped TiO₂ were detected. Sensitivity values of 3.13x10^-4 and 1.32 μA/(μMmm²), which is in an acceptable range, were evident.

Abstract: We report on the electrochemical behavior of Pt/W(111) nanfaceted surface in sulfuric acid. The Pt/W(111) nanofaceted surface was characterized by X-ray photelectron spectroscopy (XPS) and Scanning Tunneling Micrsocopy (STM) before and after the electrochemical measurements. The X-ray photoelectron spectroscopy (XPS) have shown a partial oxidation of W(111) during electrochemical measurements. Comparison of STM images before and after the electrochemical measurements enabled to locate the region where the oxidation process took place.

Abstract: This work presents investigations on preparation of 20 wt. % Pt_0.5Pd_0.5/C nanoelectrocatalysts by electroless and their electrocatalytic properties. The 20 wt. % Pt_0.5Pd_0.5/C nanoelectrocatalysts were prepared by electroless successfully. The optimum experimental conditions of the main effect factors in preparing the PtPd nanoelectrocatalysts are [Pt²⁺ or Pd²⁺] =2-10g/L, [HCHO] =10-20g/L, temperature: 40-60°C, the dosage of protection reagent: 1-3 % of the platinum and palladium content, the agitation rate 400-500r/min. The characterization of 20 wt. % Pt_0.5Pd_0.5/C was performed with cyclic voltammetry (CV) and transmission electron microscope (TEM), respectively. Particles of PtPd are distributed symmetrically on C by TEM, of which are very small and the average granularity is less than 3nm. The nanoelectrocatalysts have high stabilization and lots of catalysis nuclei through CV.

Abstract: Electrocatalytically active Ni-W alloy coatings have been developed through compositionally versatile electrodeposition method on copper substrate from tri-sodium citrate bath, using glycerol as the additive. The deposition conditions have been optimized for peak performance of their electrocatalytic behavior, like hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in 1M KOH. Corrosion behaviors of the coatings have also been tested under study conditions of electrocatalysis. Electrocatalytic behaviors were tested by cyclic voltammetry (CV) and chronopotentiometry techniques. Experimental results demonstrated that Ni-W alloy coatings, deposited at low and high current densities (c. d.) were showing superior performance for OER and HER, respectively. Better electrocatalytic activity for HER with increase of deposition c. d. was attributed by the unique phase structure, surface morphology and chemical composition of the coatings, confirmed by XRD, SEM and EDX analysis. The dependency of coating thickness and hardness on HER and OER were analyzed, and results are discussed.

Abstract: Electrocatalysis as a catalytic process involving oxidation or reduction through the direct transfer of electrons is of key importance subject in various fields of chemistry and associated sciences. Heterogeneous electrocatalysis is especially important to the development of water oxidation and fuel cells catalysts. This paper presents the brief description of the electrocatalysis and the mechanism of electrochemical reactions. Different factors and their influence on electrocatalytic activity, have been discussed. Role of nanoparticles in electrocatalysis received a particular emphasis. Long-term tasks of electrocatalysis were also definied.

Abstract: The electrocatalytic performance of graphene oxide frameworks (GOFs) for producing hydrogen peroxide is reported. Three different GOFs are synthesized by interlinking the graphene oxide sheets with different boronic acid deviates through the hydrothermal method and their electrochemical performance are investigated via cyclic voltammetry (CV) and rotating disk electrode (RDE) experiments. Through these electrochemical experiments, we find GOFs favor a 2e^- reduction pathway and perform high activity and selectivity in the hydrogen peroxide production process. Taking advantage of these catalysts for the electrochemical synthesis of hydrogen peroxide has the potential to establish a safe, sustainable, and cheap flow-reactor-based production method.

Abstract: A series of Cu₂O/TiO₂ electrodes for the enzyme-free glucose oxidation have been fabricated by secondary anodic oxidation combined electroplating method. The obtained nanocomposites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and their electrochemical behaviour measured by cyclic voltammetry (CV). The effects of preparation conditions on the morphology and performance of Cu₂O/TiO₂ for enzyme-free oxidaton of glucose were studied. For the electrochemical deposition at the potential range of −0.4 to −0.8 V, Cu²⁺ was electrochemically reduced to polyhedral Cu₂O, accompanied by the simultaneous formation of Cu with a nanoparticle morphology. It was found that the reduced particles with Cu cooperated onto the Cu₂O were completely covered on the top surface of TiO₂ nanotubes and showed a highest response current with a lower overpotential 0.5 V. The results indicate that the incorporation of Cu nanoparticles favors to improve the response current, which might find promising applications in biosensor and biological fuel cells.

Abstract: PtAu bimetallic nanoparticles (NPs) were successfully synthesized on single-stranded DNA functionalized graphene nanomaterials (ss-DNA/GR) via a simple chemical reduction method. The nanocomposites (PtAu/ss-DNA/GR) were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectrometer (EDS) and electrochemical techniques. Then a sensitive dopamine (DA) sensor was fabricated based on PtAu/ss-DNA/GR nanocomposites modified glassy carbon electrode (GCE). The results of electrochemical experiments demonstrated that the sensor exhibited excellent electrocatalytic activity to the oxidation of DA. The sensor displayed wide linear detection range from 8.0×10^-8 to 1.0×10^-5 M and 1.0×10^-5 to 5.0×10^-5 M and a low detection limit of 1.0×10^-8 M (S/N = 3). In addition, the sensor also showed high selectivity, good reproducibility and stability for DA detection. Thus, it is considered to be an ideal candidate for practical application.