Electrocatalysis最新文献

Miltefosine is an alkyllylosophospholipid analogue used to treat visceral leishmaniasis. Recently, reports have been made of suspected counterfeit miltefosine on the Indian market. With the risk counterfeit drugs pose to drug resistance development, quality control of antileishmanial drugs has become important. Hence, in this study, amino-functionalized multi-walled carbon nanotubes (MWCNT-NH₂) were synthesised and characterised using Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Also, electrochemical impedance spectroscopy and cyclic voltammetry were used to study the electrochemical properties of the synthesised MWCNT-NH₂. A complex was formed between MWCNT-NH₂ and miltefosine (Mil-MWCNT-NH₂). Five microliters of Mil-MWCNT-NH₂ was drop-cast on glassy carbon electrode, and differential pulse voltammetry studies were carried out to assess the performance of the sensor. Using [Fe(CN)₆]^-3/-4 as a redox couple, a calibration study was carried out at different concentrations (0–250 µM) to establish the concentration range of the sensor. A linear response was established. With a detection limit of 1 µM, the fabricated sensor is a viable tool for detecting antileishmanial drug miltefosine in urine samples and possible application in quality control of miltefosine against counterfeiting.

Graphical Abstract

Pesticide (glyphosate) monitoring has become a focal point of concern as the unregulated application of pesticides puts both human health and the ecosystem at serious risk. Effective tracking of glyphosate levels is essential to mitigate its adverse effects and ensure the safety of the ecosystem and the human population. This study develops a novel electrochemical (EC) sensor using a nickel-metal organic framework (Ni-MOF) modified electrode to detect ultra-low concentrations of glyphosate pesticide. A one-pot solvothermal approach to synthesize Ni-MOF and a one-step sensor fabrication approach were adopted to modify the electrode surface of an electrochemical sensor. The Ni-MOF material coating on the working electrode surface increases the electrode’s electroactive surface area, promotes electron transport between the electrodes, and demonstrates selectivity and sensitivity towards glyphosate. This electrochemical sensor has a detection limit of 1.9 parts per billion (ppb) or 0.0113 nM, over an extensive concentration range of 0.166–0.666 µM/L. Further, the proposed sensor exhibits excellent stability and reproducibility with a standard deviation of around 2.8% in relative peak current. It shows excellent selectivity against various interfering substances with approximately ≤ 5% change in the current response. Finally, to showcase its practical applicability, the sensor was assessed by a glyphosate-spiked real sample.

Graphical Abstract

The development of active bifunctional electrocatalysts is crucial in reducing dependence on precious-metal-based materials for energy production and storage. In this work, we present the synthesis of novel nanocomposites of XCoFe₂O₄ (where X represents Pr or Nd) integrated with graphene oxide (GO) using a hydrothermal method for light-induced hydrogen evolution reaction (HER) and supercapacitor functions. Among the synthesized electrocatalysts, NdPr-CoFe₂O₄/GO exhibits superior HER performance, characterized by a minimal overpotential at photocurrent density of 10 mA cm⁻² in 1 M KOH solution. Additionally, the composite shows a high specific capacitance of 1590.5 F/g at 3 A/g, maintaining approximately 97.6% of its capacitance after 1000 cycles. The enhanced performance is attributed to the synergistic effects of optimal bimetallic substitution, maximized electrochemical surface area, reduced particle size, and minimized charge transfer resistance. This study opens new pathways for the design of spinel ferrite-GO composites for efficient energy conversion and storage applications.

Graphical Abstract

Graphical abstract presenting applications of synthesized catalysts.

The impact of TaO_x interlayers prepared by thermal decomposition using different solvents (ethanol, n-butanol, ethylene glycol) on Ti/TaO_x/IrO₂-Ta₂O₅ electrodes has been investigated using analytical methods such as SEM, XRD, XPS, FIB-TEM, and electrochemical techniques. The results demonstrate that the synthesized TaO_x interlayers are mainly composed of amorphous TaO_x and a little of Ta₂O₅ crystallites with a thin TiO_x sublayer on titanium substrate. The solvents affect the TaO_x loadings and fractions of surface cracks due to the difference in viscosity. The Ti/TaO_x/IrO₂-Ta₂O₅ electrode with the interlayer prepared using ethylene glycol has the largest electrochemically active surface area and electrocatalytic activity for oxygen evolution reaction, while the electrode with the TaO_x interlayer formed using n-butanol as solvent presents highest stability.

Graphical Abstract

It is well known that direct alcohol fuel cells (DAFCs) are ideal power sources for portable equipment and electric vehicles, due to the advantages of alcohol, such as renewability, safety, high energy density and ease of storage and transportation. However, their applications are limited by the scarce resources and poor operational durability of commercial Pt-based catalysts. Consequently, numerous alternative catalysts have been reported over the past decades, including MOF (Metal–Organic Framework) materials, M–N-C (M = transition metal atom) single-atom catalysts, Pd-based catalysts and others. Among these, Pd-based catalysts exhibit high electro-activity for both alcohol electro-oxidations and oxygen reduction reactions, particularly for ethanol electro-oxidation. Significant efforts have been made to enhance the activity and durability of Pd-based catalysts for use in DAFCs. Despite these efforts, commercialization is progressing slowly. Therefore, advancing the commercial application of DAFCs has become a pressing issue for both enterprises and researchers. Exploring novel Pd-based catalysts with exceptionally high activity and stability is likely to address this challenge. This review summarizes the classifications, synthesis methods, current research status and prospects of Pd-based catalysts to provide effective research directions and methods for improving their investigation.

Graphical Abstract

Electrocatalysts play a critical role in various energy conversion and storage technologies, including fuel cells, electrolyzers, and batteries. However, finding the optimal electrocatalyst for a specific reaction is a challenging and time-consuming task, as there are many possible materials and compositions to explore. Bipolar electrode (BPE) arrays are a promising technique for high-throughput screening of electrocatalysts, as they allow simultaneous testing of multiple candidates under identical conditions without external wiring. This mini-review summarizes recent advancements and current challenges in developing and applying BPE arrays for electrocatalyst screening. We discuss the design and fabrication of BPE arrays, the methods for depositing electrocatalysts on BPEs. We also highlight some examples of BPE arrays for screening electrocatalysts for various reactions, such as oxygen reduction, hydrogen evolution, and organic oxidation. We conclude with some perspectives and suggestions for future research directions in this emerging field.

Graphical Abstract

A platinum-based complex molecule, [PtLCl]Cl (Pt-L), featuring a tridentate ligand (L = 2,6-bis(benzimidazol-2-yl)-4-hydroxypyridine) was synthesized. Subsequently, Pt-L was successfully bonded to amine-terminated Fe₃O₄NP, and MWCNTs were incorporated into the modified Fe₃O₄ surface. The resulting electrode was shown to possess outstanding electrocatalytic activity for detecting H₂O₂ and NADH, characterized by enhanced cathodic or anodic peak responses and favorable shifts in the reduction or oxidation peak potentials for both analytes. The sensing platform demonstrated excellent electrochemical performance in non-enzymatic measurements of H₂O₂ and NADH, achieving notably low detection limits of 0.017 µmol L⁻¹ for H₂O₂ and 0.113 µmol L⁻¹ for NADH. These findings were acquired within the concentration range of 10 to 500 µmol L⁻¹, indicating the linear portion of the calibration graphs obtained in the concentration ranges of 10 to 5000 µmol L⁻¹ for H₂O₂ and 10 to 25,000 µmol L⁻¹ for NADH, which exhibited exponential behavior for both analytes. The developed sensor displayed high responsiveness, long-lasting stability, and requisite interference, rendering it suitable for routine detection of H₂O₂ and NADH in biological specimens.

Graphical Abstract

PEM fuel cell technologies have emerged as promising candidates for advancing sustainable energy solutions, primarily due to their exceptional efficiency and minimal environmental impact. However, the widespread commercialization of fuel cells is hindered by the high cost and limited availability of platinum catalysts, which play a critical role in facilitating electrochemical reactions. This research mainly focused on investigating innovative solutions aiming to mitigate platinum loading while simultaneously preserving or potentially enhancing their performance. To this end, the impact of two distinct surfactants, Tween 40 and Tween 80, was examined to assess their influence on the synthesis and characteristics of platinum nanoparticles immobilized on carbon supports. Subsequently, their electrochemical activities were compared. The catalysts were synthesized using the polyol method with the incorporation of surfactants, and their performance was compared with that of Pt/C catalysts without surfactants. TGA analysis indicated a significant reduction of approximately 12% in the Pt content of the catalyst synthesized using Tween 80 surfactant. However, CV analysis revealed a remarkable increase of 85% in the ECSA for the same catalyst. Furthermore, significant improvements in the performance of this catalyst were also observed in the single-cell test setup. The high performance achieved with a lower Pt content in the catalyst layer highlights its potential for large-scale commercialization.

Graphical Abstract

Due to its layered structure and appropriate electronic configuration, two-dimensional MoS₂ has been considered a reliable and inexpensive electrocatalyst and electrode material for the oxygen reduction reaction (ORR). Additionally, the MoS₂ and reduced graphene oxide (rGO) structure can act as a good host for other nano-catalysts. However, the catalytic activity of pristine MoS₂ is not as effective as the industrial targeted values. In this work, nickel-MoS₂ (Ni/MoS₂) and Ni/MoS₂-rGO composites are synthesized and evaluated as catalysts for ORR at the cathode. Electrochemical studies using a rotating disk electrode system confirmed that the as-synthesized catalyst exhibits good electrocatalytic activity to ORR in alkaline media (0.1 M KOH) and followed the desirable 4-electron transfer process. Ni/MoS₂-rGO composite displays a current density of − 11.1 mA/cm² and half-wave and onset potentials of 0.74 V and 0.87 V, respectively, at 2400 rpm, whereas the bare MoS₂ shows the values of limiting current density, half-wave potential, and onset potential of − 5.8 mA/cm², 0.61 V, and 0.79 V, respectively. Numerous highly active Mo sites, high conductivity, and high specific surface area in MoS₂-rGO make it a novel catalyst material for ORR. Ni further enhances conductivity and is involved in electrochemical reactions. The onset potential slightly shifts towards the lower value after the potential cycling, whereas the limiting current density decreases by ≈9.0% for Ni/MoS₂-rGO, which shows its good stability in alkaline media. Therefore, Ni/MoS₂-rGO composite can be a good candidate for electrode catalyst material for alkaline fuel cells.

Graphical Abstract