NiSn nanoparticle-incorporated carbon nanofibers as efficient electrocatalysts for urea oxidation and working anodes in direct urea fuel cells (original) (raw)
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RSC Advances, 2022
Herein, we report a chemical method for scalable synthesis of spherical Ni/NiO nanoparticle-decorated nanoporous carbon (NNC) based electrocatalytic system using a simple and easy chemical method with ultra-high activity towards urea electrooxidation. Morphological analysis by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HR-TEM) confirms the formation of Ni/NiO NPs on highly nanoporous carbon with an average size of ∼50 nm. X-ray diffraction (XRD) confirms NNC with a face-centred cubic (FCC) crystal structure. Ni/NiO NPs intercalated with nanoporous carbon exhibited the best electrocatalytic performance towards urea oxidation with an ultra-low onset potential of ∼0.33 V vs. SCE, and faster electrokinetic mechanism confirmed from Tafel slope (∼45 mV dec −1), EIS R ct (∼6.98 U), and long term durability for 7 h at 10 mA cm −2 with high CO poisoning tolerance. This work affords noble metal-free electrocatalysts for novel appliances and remarkable potential for urea determination, hydrogen generation, real-time water remediation, and energy conversion.
Improvement of the electrocatalytic activity of nickel toward methanol oxidation can be conducted by exploiting the synergetic influence of a co-catalyst and/or utilizing a proper support. In this study, utilizing tin as a co-catalyst and supporting on carbon nanofibers are proposed to enhance methanol oxidation in the alkaline media. Typically, NiSn nano-particles alloy-incorporated carbon nanofibers could be prepared by calcination of elec-trospun nanofibers composed of poly (vinyl alcohol), nickel acetate tetrahydrate and tin chloride under argon atmosphere at a high temperature. The influence of the co-catalyst content and the calcination temperature on the morphology, composition and electro
In this study, the influence of nitrogen doping on the electrocatalytic activity of carbon nanofibers incorporated with nickel nanoparticles toward methanol oxidation is introduced. The modified carbon nanofibers have been synthesized from calcination of electrospun nanofiber mats composed of nickel acetate tetrahydrate, poly(vinyl alcohol) and urea in argon atmosphere at 750 ◦C. The utilized physicochemical characterizations indicated that the proposed strategy leads to form carbon nanofibers having nickel nanoparticles and doped by nitrogen. Formation of pure nickel can be attributed to the abnormal decomposition of the acetate anion which leads to form strong reducing gases (CO and H2), the formed nickel catalyzes graphitization of the utilized polymer to form carbon nanofibers. Investigation of the electrocatalytic activity indicated that nitrogen doping strongly enhances the oxidation process of methanol as the current density increases from 52.5 to 198.5 mA/cm2 when the urea content in the original electrospun solution was 4 wt% urea. Moreover, the nanofibrous morphology exhibits distinct impact on the electrocatalytic activity. Also, nitrogen-doping enhanced the stability of the introduced Ni-based electrocatalyst.
International Journal of Hydrogen Energy, 2019
Nickel hydroxide nanoparticles were fabricated on Vulcan XC-72R carbon black using various reducing agents through assisted microwave polyol process. The formed electrocatalysts using sodium borohydride [Ni(OH) 2 /CeNB], ethylene glycol [Ni(OH) 2 /CeEG] and a mixture of them [Ni(OH) 2 /CeEGNB] displayed an electrocatalytic activity towards urea oxidation in NaOH solution. The oxidation peak potential and current density values were greatly influenced by the employed reducing agent. Lower onset and peak potential values were measured at Ni(OH) 2 /CeEGNB, while Ni(OH) 2 /CeEG exhibited the highest oxidation current density during urea oxidation reaction. Electroactive surface area measurements revealed that the number of available active sites for the oxidation reaction was arranged in an ascending order as Ni(OH) 2 /CeNB < Ni(OH) 2 /CeEGNB < Ni(OH) 2 /CeEG. The diffusion coefficient of urea molecules at Ni(OH) 2 /CeEG and Ni(OH) 2 /CeEGNB was 14.69 and 5.90 times higher than that at Ni(OH) 2 /CeNB. Stable performance was measured at all studied electrocatalysts over prolonged operation suggesting their valuable application as efficient anode materials in direct urea oxidation fuel cells.
AuCu nanofibers for electrosynthesis of urea from carbon dioxide and nitrite
2021
Carbon dioxide reduction reaction (CO2RR) is a promising technology for mitigating greenhouse gas emission and achieving carbon neutrality. However, coupling CO2RR with other reactions to produce high value-added chemicals remains a challenge. In this work, we report self-assembled nanofibers composed of ultra-thin AuCu alloy nanowires possessing a Boerdijk-Coxeter structure with (111)-dominant facets for the electrosynthesis of urea by coupling CO2RR with nitrite reduction reaction (NO2−RR). The rich structural defects and AuCu bimetallic alloy composition provide a large number of highly catalytically active sites. The constructed AuCu nanofibers display excellent urea synthesis performance in the electrolyte solution containing 0.01 M KNO2 with continuous drumming of CO2, achieving a high urea yield rate of up to 3889.6 µg h− 1 mg− 1cat. and a high Faraday efficiency of 24.7% at -0.9 V. This work provides a feasible method for the rational design of self-assembled bimetallic nano...
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2019
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Two dimensional Cu based nanocomposite materials for direct urea fuel cell
International Journal of Hydrogen Energy, 2021
In this work, Cu2O nanoparticles were successfully prepared onto the surface of twodimensional graphitic carbon nitride (g-C3N4) by using a simple solution chemistry approach. An environment-friendly reducing agent, glucose, was used for the synthesis of Cu2O NPs onto the surface of g-C3N4 without using any surfactant or additives. The surface composition, crystalline structure, morphology, as well as other properties have been investigated using XPS, XRD, SEM, FTIR, FESEM, EDS, etc. The electrochemical measurements of the prepared materials demonstrated that Cu2O exhibited a weak oxidation activity towards urea, while g-C3N4 has no activity towards urea oxidation. The Cu2O supported on the surface of g-C3N4 (Cu2O-g-C3N4) demonstrated a significant activity towards urea oxidation that reached two times that of the unsupported one. The significant increase in the performance was related to the synergetic effect between the Cu2O and g-C3N4 support. The prepared composite materials demonstrated high stability towards urea oxidation as confirmed from the stable current discharge for around three hours without any noticeable degradation performance.
Electrochimica Acta, 2020
Hydrogen production from natural resourses and industrial waste water is of vital and duel importance to the energy and environmental issues. Urea oxidation based on cost effictive catalyst and which is substuation to the noble based electrolysers like Pt, Pd and Rh of great challange. Herein, we have fabricated effective decoration of Ni NPs on GO by chemical reduction approach and characterized by Furrier transfarm infra red (FTIR) spectroscopy, X-ray diffraction (XRD), transmissio electron microscopy (TEM), Raman spectroscopy, BET surface area measurements and X-ray photoelectron spectroscopy (XPS). In the morphological studies TEM confirms the Ni NPs (~10 nm) on GO (~20 nm thickness) and XRD confirms its FCC crystal structure. Further, Raman spectroscopic analysis showed the increment of I D /I G ratio more than double in GO compared to Ni@GO supports decoration of Ni NPs on GO. BET analysis also supports Ni@GO having higher surface area compared to Ni NPs and GO individuals, More significantly, binding energy of Ni is zero-valent confirmed from XPS of Ni@GO. Electrochemical activity of Ni@GO from cyclic voltammetry (CV) shows the ultrahigh current density is of 27 mA/cm 2 at an ultralow onset potential of 0.30 V vs SCE having long term stability. Electrochemical impedance spectroscopy (EIS) shows the highly sensitive towards the urea oxidation reaction on Ni@GO nanocomposite. The electrocatalytic activity on Ni@GO is pH sensitive towards urea oxidation.