Papers by Keyword: Oxygen Reduction Reaction

Abstract: Prussian Blue Analogues (PBAs) have emerged as promising materials for energy storage and conversion applications. In this study, we synthesized PBA derivatives doped with Mn, Co, Ni, Zn, and Cu, supported on nitrogen-doped carbon aerogels (NCA), and evaluated their potential as bifunctional electrocatalysts for rechargeable zinc-air batteries. Structural and morphological analyses revealed the homogeneous dispersion of metal species in the NCA framework, ensuring effective active site exposure. Electrochemical characterizations demonstrated that MnCoNiZnCuPBA@NCA exhibited superior oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) performance, as evidenced by its high current density, low overpotential, and excellent Tafel slope. Furthermore, MnCoNiZnCuPBA@NCA achieved the highest discharge capacity (601.80 mAh.g-1) and energy density (322.67 mWh.g-1) among the materials studied, along with remarkable cycling stability. These findings underscore the potential of MnCoNiZnCuPBA@NCA as an efficient and durable bifunctional electrocatalyst for next-generation zinc-air batteries.

Abstract: In the field of fuel cell technology, the development of cost-effective catalysts is crucial for the commercialization of Alkaline Membrane Fuel Cells (AMFCs). Platinum (Pt) has traditionally been employed as the catalyst in AMFCs, but its high cost poses a major barrier to widespread adoption. In this study, a new catalyst material was developed by incorporating Manganese Dioxide (α-MnO₂) into Carbon Nanotubes (CNTs) using hydrothermal synthesis techniques. The synthesized catalyst was characterized using Scanning Electron Microscopy (SEM) and X-ray diffraction (XRD), and its electrocatalytic activity was evaluated through Linear Sweep Voltammetry (LSV) and CV through Rotating Disc Electrode (RDE) experiments. The results showed that the α-MnO₂-CNT composite displayed strong durability in the alkaline environment and high electrocatalytic activity for oxygen reduction reaction (ORR). The LSV measurements revealed a current density of -4.1 mA/cm² and an overpotential of -0.3V relative to Standard Calomel Electrode (SCE) in a 0.1M KOH electrolyte. Additionally, the α-MnO₂-CNT composite displayed high methanol tolerance and long-term stability compared to commercial Pt/C catalysts. This study demonstrates that the use of α-MnO₂-CNT as a cost-effective alternative to Pt has the potential to facilitate the commercialization of AMFC technology.

Abstract: In this study, synthesis of reduced graphene oxide-iron oxide-silica dioxide (rGO/Fe₃O₄/SiO₂) was done through a facile chemical process. Physical characterization was carried out as such Fourier transform infrared spectroscopy (FTIR) which confirmed the presence of silica peak in the spectrum of rGO/Fe₃O₄/SiO₂, while RAMAN displayed the vibrational bands of carbon materials studied. Results of SEM-EDX and TEM confirmed the unification of SiO₂ on rGO/Fe₃O₄ nanocomposite with difference in morphologic structure. X-ray diffraction (XRD) analysis exhibited that addition of SiO₂ increased the crystalline size of the nanocomposite. Nitrogen adsorption isotherm analysis describes the nanocomposites fall in the mesopore region. The nanocomposite was then drop-casted on the surface of glassy carbon electrode (GCE) for fabrication of the electrode which denoted as rGO/Fe₃O₄/SiO₂/GCE. Electrochemical characterization of modified electrode was studied using electron impedance spectroscopy (EIS), which showed the minimal resistance charge transfer. Oxygen reduction reaction analysis shows that electrocatalytic reduction of oxygen was excellent with four-electron transfer when calculated using Randles-Sevcik equation. All the analysis was compared to the nanocomposites without the addition of silica oxide (rGO/Fe₃O₄)_. This work proves that addition of nanoparticle in a compound as a matrix improves the oxygen reduction potential of rGO/Fe₃O₄/SiO₂/GCE composite.

Abstract: Some areas in Indonesia have difficulty accessing electricity [1]. One of the alternative is sea water battery because of its good theoretical performance and great seawater potential in Indonesia [2]. However the performance is limited by the sluggish Oxygen Reduction Reaction, therefore electrocatalyst is needed to increase the rate of reaction [2]. Oil palm empty fruit bunch carbon aerogel is one of the alternative because of its excellent electrocatalytic performance and can be made from abundant material with high content of cellulose [3]. Carbon aerogel can be obtained from pyrolizing oil palm empty fruit bunch based aerogel cellulose. Activity of the Oxygen Reduction Reaction can be determined from pyridinic N concentration in the carbon aerogel [4]. This research focuses on synthesizing nitrogen-doped carbon aerogel from oil palm empty fruit bunch and characterized its electrocatalytic performance. Research started with synthesizing cellulose aerogel with urea-ammonia crosslinking precursor and followed by pyrolysis of cellulose aerogel to carbon aerogel at 600°C. Samples were characterized using FTIR, XRD, CV, LSV, and LP. The FTIR Spectra analysis shows that the carbon aerogel was N-doped with pyridinic N. Electrochemical performance analysis in 3.5% NaCl as electrolyte shows that carbon aerogel undergoes 2-electron ORR pathway with kinetic current density of i_k=0.107 mA/cm² and current density of i_o=0.295 μA/cm².

Abstract: Performance of seawater batteries is still limited by the sluggish nature of oxygen reduction reaction (ORR). One way to optimize the performance of the battery is by utilizing an electrocatalyst with the ability to increase the ORR rate of reaction. Nitrogen-doped carbon aerogel based on coir fiber is one of the alternatives because of its excellent electrocatalytic performance and was made from an abundant material. Carbon aerogel was obtained from pyrolyzing coir fiber-based aerogel cellulose. Nitrogen atom structure in carbon aerogel was affected by the temperature of cellulose aerogel pyrolysis. Pyridinic N content in the Nitrogen-doped carbon aerogel has effective for the activity of the ORR. The electrocatalytic performance of the carbon aerogel synthesized from coir fiber with nitrogen doping at the pyrolysis temperature of 600 °C was investigated in this study. The research process began with the synthesis of cellulose aerogel using urea-ammonia crosslinking precursor. Next, cellulose aerogel was pyrolyzed at 600 °C to create carbon aerogel. FTIR, XRD, CV, LSV, and LP were used to characterize the samples. The carbon aerogel was N-doped with pyridinic N, according to an analysis of the FTIR spectra. The carbon aerogel shows 4-electron ORR with kinetic current density (i_k) of 0.74 mA/cm² and current density (i_o) of 0.583 μA/cm², according to electrochemical performance analysis in 3.5% NaCl as electrolyte.

Abstract: In this work, the Cu-alginate/graphene aerogels were prepared by using alginate, graphene and copper chloride as precursors by a freeze-drying process. Finally, N-doped carbon aerogels supported by Cu nanoparticles (NPs) (Cu/N-CAs) were obtained through annealing in the NH₃ atmosphere. The morphology, microstructures, specific surface area, and pore size distribution were studied by SEM, XRD, and BET analysis. The results showed that a significant amount of Cu NPs were uniformly disseminated on the aerogels’ surface, and the catalysts’ specific surface area reached 141 m²/g. Electrochemical tests revealed good catalytic capabilities for the oxygen reduction reaction (ORR) of the as-obtained Cu/N-CAs. Compared to the commercial 20%Pt/C, the Cu/N-CAs exhibited comparable catalytic performance, superior catalytic stability and methanol resistance. The transfer of 3.94 electrons indicated that the Cu/N-CAs were undergoing a four-electron (4e^-) ORR process.

Abstract: A highly active Platinum Group Metal (PGM) and non-PGM electrocatalysts with thermally extruded nanotubes have been prepared for Proton Exchange Membrane (PEM) fuel cell by sintering Nickel zeolitic imidazole framework (Ni-ZIF). Preeminent electro-catalytic activities have been observed through single fuel cell tests and rotating disk electrode (RDE). This study involves the comparison of Oxygen Reduction Reaction (ORR) activities and fuel cell (FC) test station performance of two catalyst Nickel and Platinum mixed Nickel nanotubes (Ni NT, Ni/Pt NT) respectively. The acidic cells with corresponding Ni and Ni/Pt catalysts delivers peak power densities of 325 mWcm^-2 and 455 mWcm^-2 at 75 °C inside fuel cell. Our results indicate that, the synthesized Nickel nanotubes has profound effect on catalytic performance of both PGM and non-PGM electro catalysts.

Abstract: High platinum requirements in electrocatalyst bring about huge expenditure, which hinders the commercialization and wide adoption of proton electrolyte membrane fuel cells (PEMFCs). Therefore, developing new fuel cell catalysts with excellent oxygen reduction reaction (ORR) performance may be a potential way to solve this drawback. In this paper, a facile ultrasonic-assisted method is introduced to synthesize bimetallic PtCo nanoparticles supported on three-dimensional reduced graphene oxide (Pt-Co/3DrGO). Results indicate that PtCo nanoparticles with alloy structure, small size (12.4 nm), and uniform distribution are well-dispersed onto rGO sheets. With 3D porous structure, the fabricated Pt-Co/3DrGO catalyst exhibits better ORR activity and long-term stability than that of commercial Pt/C (20 wt%). The increased electrocatalytic activity is attributed to the formation of 3D porous structure together with the effective surface structure and the highly uniform distribution of the PtCo alloy nanoparticles on rGO sheets.

Abstract: Large quantity of iodinated charcoal (I-AC) is firstly prepared by simple ball-milling activated chargoalin the presence of iodine. The resultant I-AC contains iodine of 0.59 at.% (EDS) and shows that the morphology is changed from random powder into flake-like platelet. It is uased as electrocatalyst for oxygen reduction reaction (ORR), exhibiting outstanding electrocatalytic activities with higher selectivity, better tolerance to methanol crossover than those of the starting AC and commercial Pt/C electrocatalysts.

Abstract: Nitrogen-doped carbon nanotubes (N-CNTs) have beenprepared on FeNi catalyst by plasma-enhanced chemical vapor deposition in amixture of N₂, O₂, and CH₄. On the opened topof CNT, multi-layer graphene grown self-assembly was observed by transmissionelectron microscopy and high resolution transmission electron microscopy. Thenanohybrid film analyzed by scanning electron microscopy exhibited a porous and3D morphology and pyridinic and graphitic nitrogen structure confirmed by x-rayphotoelectron spectroscopy. Electrochemical measurement indicated that the filmfacilitated about three-electron transferpathway for oxygen reduction reaction in neutral medium and two-electronreductions in both alkaline and acidic solutions.