Bifunctional cobalt oxide (Co3O4) nanowire catalysts grown on carbon cloth (CC) fibers and their modification with nickel oxide (NiO) and manganese dioxide (MnO2) to produce core–shell ...nanoarchitectures are explored as catalysts for urea oxidation reaction and oxygen reduction reaction in direct urea fuel cells (DUFC). Based on a systematic electrochemical characterization of the catalyst, the as‐developed core–shell nanoarchitectures are optimized toward DUFC performance. Under alkaline conditions with an anion exchange membrane, the DUFC with a cell configuration of Co3O4@NiO(1:2)/CC(a|c)Co3O4@MnO2(1:2)/CC exhibits a maximum power density of 33.8 mW cm−2 with excellent durability for 120 h without any performance loss. Furthermore, the DUFC exhibits a maximum power density of 23.2 mW cm−2 with human urine as a fuel. These findings offer an approach to convert human waste into treasure.
A sustainable energy generation with direct urea fuel cells (DUFC) is demonstrated by utilizing Co3O4@NiO and Co3O4@MnO2 grown on carbon cloth fibers, respectively, as urea oxidation and oxygen reduction reaction catalysts. The core–shell architecture of the nanocatalysts enables the DUFC to deliver high power density and excellent stability with urea or human urine as fuels.
Iron oxide (Fe
O
) nanoparticles anchored over sulfonated graphene oxide (SGO) and Nafion/Fe
O
-SGO composites were fabricated and applied as potential proton exchange membranes in proton exchange ...membrane fuel cells (PEMFCs) operated at high temperature and low humidity. Fe
O
nanoparticles bridge SGO and Nafion through electrostatic interaction/hydrogen bonding and increased the intrinsic thermal and mechanical stabilities of Nafion/Fe
O
-SGO composite membranes. Nafion/Fe
O
-SGO composite membranes increased the compactness of ionic domains and enhanced the water absorption and proton conductivity while restricting hydrogen permeability across the membranes. The proton conductivity of Nafion/Fe
O
-SGO (3 wt%) composite membrane at 120 °C under 20% relative humidity (RH) was 11.62 mS cm
, which is 4.74 fold higher than that of a pristine recast Nafion membrane. PEMFC containing the Nafion/Fe
O
-SGO composite membrane delivered a peak power density of 258.82 mW cm
at a load current density of 640.73 mA cm
while operating at 120 °C under 25% RH and ambient pressure. In contrast, under identical operating conditions, a peak power density of only 144.89 mW cm
was achieved with the pristine recast Nafion membrane at a load current density of 431.36 mA cm
. Thus, Nafion/Fe
O
-SGO composite membranes can be used to address various critical problems associated with commercial Nafion membranes in PEMFC applications.
Flexible and 3D carbon aerogels (CAs) composed of carbon nanotubes (CNTs) with carbon shell‐confined binary palladium–nickel (Pdx–Niy) nanocatalysts on carbon fibers (Pdx–Niy/NSCNT/CA) have been ...developed through a facile chemical vapor deposition method. The 3D porous carbon network and the synergistic effect of carbon shell‐confined bimetal nanoparticles of rationally constructed aerogels facilitate enhanced electrocatalytic and antipoisoning activities toward ethylene glycol (EG) oxidation reaction compared to the commercial Pt/C catalyst. With the 3D morphological features and direct growth of Pd–Ni bimetallic nanoparticles encapsulated CNTs on carbon fibers, the Pd52–Ni48/NSCNT/CA delivers a maximum microfluidic direct ethylene glycol fuel cell (µDEGFC) power density and durability of, respectively, 62.8 mW cm−2 and 60 h. The superior performance observed, with Pd52–Ni48/NSCNT/CA amongst the catalysts reported in the literature, opens an exciting research avenue towards powering next‐generation, portable electronics.
A biomass derived 3D cotton aerogel with carbon shell‐confined Pd–Ni nanoparticles in carbon nanotubes is realized as a free‐standing, bendable anode for efficient ethylene glycol oxidation. The 3D porous structure facilitates ion/electron transport through a rapid diffusion of electrolyte and Pd–Ni nanoparticles in the tips of CNTs and catalytically activates the outer graphitic layers and promotes microfluidic direct ethylene glycol fuel cell performance.
The increasing demand for the development of highly sensitive, selective and precise non-enzymatic electrochemical sensors (NEGS) for the quantitative and qualitative analysis of glucose in clinical, ...pharmaceutical and industrial sectors has garnered attention worldwide. The electroactive materials are catalytically oxidized glucose molecules that generate signals for glucose quantification; graphene and its derivatives are highly useful as active conductive supports for high-performance NEGS. Since the discovery of graphene in 2004, the astonishing properties of graphene-based platforms have resulted in its extensive applications in NEGS. Although a number of research efforts have involved the development of NEGS with graphene and its composites, a comprehensive study of NEGS using graphene and its composites has yet to be envisioned; this has not only obscured their widespread application but has also diminished future improvements in NEGS. Hence, this review article is presented to visualize the significant requirements of NEGS catalysts, the influences of graphene in achieving the requirements of NEGS catalysts and the progress made on graphene platform-equipped NEGS, along with a detailed discussion of recent studies and the involved electrochemical mechanisms. Building on the above perspectives, the fine tuning of the sensitivities and detection limits of graphene-based platforms in the fabrication of NEGS have also been detailed. Furthermore, this article clearly outlines future directions by detailing the obstacles currently facing graphene-equipped NEGS; as such, this review article can be considered to be a useful guide in the design and development of next-generation NEGS.
This review elucidates the recent advances in graphene platforms in electrochemical non-enzymatic glucose sensors and provides solutions for existing bottlenecks.
The orchestrated network of octahedron shaped Cu organic framework is developed via a simple aging protocol, and the partial cation swap reactions between Cu and Ni nodes in the Cu2-paddlewheel units ...of Cu-MOF generates Cu-Ni-MOF with similar octahedron morphology. Exploiting Cu-Ni-MOF as a template, the uniformly disseminated and tightly pinned CuO/NiO spherical nanoparticles with hierarchical carbon are developed under controlled thermal and atmospheric conditions. The MOFs and metal oxide-carbon nanocomposites coated over the cello tapes (CTs) are exploited as electrochemical sensor probes for nonenzymatic glucose sensing. It adequately swamps the impediments of prevailing glucose sensor probes including time depletion, high cost, monotonous electrode cleaning and modification processes, and use of swellable inactive binders. Owing to the subsistence of an interconnected network and synergistic effect of bimetallic oxides, CuO/NiO-C expedites the considerable electrocatalytic behavior toward glucose sensing. Furthermore, the fabricated CuO/NiO-C/CT exercises the diagnosis of glucose in human serum samples. These flexible electrochemical sensor probes acquiesce the device to sustain deformation with high efficacy, opening an appealing access for the evolution of cost-efficient, binder-free, reliable, flexible, and eco-friendly sensing platforms for the development of futuristic electrochemical sensor devices.
The facile, time and cost efficient and environmental benign approach has been developed for the preparation of Nickel (Ni)-Cobalt (Co) alloy nanowires filled multiwalled carbon nanotubes (MWCNTs) ...with the aid of mesoporous silica nanoparticles (MSN)/Ni-Co catalyst. The controlled incorporation of Ni-Co nanostructures in the three dimensional (3D) pore structures of MSN yielded the catalytically active system for the MWCNT growth. The inner surface of MWCNTs was quasi-continuously filled with face-centered cubic (fcc) structured Ni-Co nanowires. The as-prepared nanostructures were exploited as non-enzymatic electrochemical sensor probes for the reliable detection of glucose. The electrochemical measurements illustrated that the fabricated sensor exhibited an excellent electrochemical performance toward glucose oxidation with a high sensitivity of 0.695 mA mM
cm
, low detection limit of 1.2 μM, a wide linear range from 5 μM-10 mM and good selectivity. The unprecedented electrochemical performances obtained for the prepared nanocomposite are purely attributed to the synergistic effects of Ni-Co nanowires and MWCNTs. The constructed facile, selective and sensitive glucose sensor has also endowed its reliability in analyzing the human serum samples, which wide opened the new findings for exploring the novel nanostructures based glucose sensor devices with affordable cost and good stability.
Microbial fuel cells (MFC) are considered as the futuristic energy device that generates electricity from the catalytic degradation of biodegradable organic wastes using microbes, which exist in ...waste water. In MFCs, oxygen serves as a cathodic electron acceptor and oxygen reduction kinetics played a significant role in the determination of overall efficiency. A wide range of strategies have been developed for the preparation and substantial modification of oxygen reduction reaction (ORR) catalysts to improve the maximum volumetric power density of MFCs, in which the efforts on graphene based ORR catalysts are highly imperative. Although numerous research endeavors have been achieved in relation with the graphene based ORR catalysts applicable for MFCs, still their collective summary has not been developed, which hinders the acquirement of adequate knowledge on tuning the specific properties of said catalysts. The intension of this review is to outline the significant role of ORR catalysts, factors influencing the ORR activity, strategies behind the modifications of ORR catalysts and update the research efforts devoted on graphene based ORR catalysts. This review can be considered as a pertinent guide to understand the design and developmental strategies of competent graphene based ORR catalysts, which are not only applicable for MFCs but also for number of electrochemical applications.
•ORR mechanisms involved in the MFCs have been explained.•Essential requirements of ORR catalysts applicable for MFCs have been elicited.•Preparation strategies of graphene based ORR catalysts have been discussed.•Salient insights of graphene based ORR catalysts applied in MFCs have been derived.•Promising solutions are proposed to tackle the limitations of graphene ORR catalysts.
Direct urea fuel cells (DUFCs) are considered as promising green energy devices for sustainable energy generation from human waste; however, the lack of efficient urea oxidation reaction ...electrocatalysts remains a formidable challenge for their practical utility. Herein, we report a flexible, binder-free electrode with a 3-dimensional (3D) hierarchical nickel cobaltite (NiCo2O4) architecture on carbon cloth (CC) fibers for high-performance DUFCs. Benefitting from its unique catalytic nanoarchitecture and direct growth on carbon fibers, NiCo2O4/CC-12 demonstrates maximum DUFC power density and durability of 38 mW cm−2 and 180 h, respectively, which significantly outperform DUFC efficiencies reported previously for other catalysts. The influence of dimension, morphology, and chemical structure of the prepared catalysts towards DUFC performance is detailed. Furthermore, considerable improvement in DUFC performance along with enhanced durability is also achieved for NiCo2O4/CC-12 with human urine, offering a novel technological platform for the conversion of human waste into sustainable energy.
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•Fe3O4 nanoparticles anchored graphene was synthesized by solanum trilobatum extract.•The growth mechanism of Fe3O4 nanoparticles anchored over graphene was detailed.•The interactions ...exerted between composite and dye molecules was proposed.•High surface area and extended active sites of composite completely degraded the dye.
The reduced graphene oxide (RGO)/Fe3O4 nanocomposites were synthesized through a facile one-pot green synthesis by using solanum trilobatum extract as a reducing agent. Spherical shaped Fe3O4 nanoparticles with the diameter of 18nm were uniformly anchored over the RGO matrix and the existence of fcc structured Fe3O4 nanoparticles over the RGO matrix was ensured from X-ray diffraction patterns. The amide functional groups exist in the solanum trilobatum extract is directly responsible for the reduction of Fe3+ ions and GO. The thermal stability of GO was increased by the removal of hydrophilic functional groups via solanum trilobatum extract and was further promoted by the ceramic Fe3O4 nanoparticles. The ID/IG ratio of RGO/Fe3O4 was increased over GO, indicating the extended number of structural defects and disorders in the RGO/Fe3O4 composite. The catalytic efficiency of prepared nanostructures toward methylene blue (MB) dye degradation mediated through the electron transfer process of BH4− ions was studied in detail. The π–π stacking, hydrogen bonding and electrostatic interaction exerted between the RGO/Fe3O4 composite and methylene blue, increased the adsorption efficiency of dye molecules and the large surface area and extended number of active sites completely degraded the MB dye within 12min.
The magnetite needle like nanorods and its core-shell architecture with silica were incorporated into the sulfonated poly(vinylidene fluoride) (sPVdF) membrane and the influence of nanofillers ...towards direct methanol fuel cell (DMFC) performances was investigated in detail. The morphological properties enunciated that magnetite@silica needle like nanorods were uniformly distributed over the sPVdF matrix. The sulfonated magnetite@silica positively influenced the water uptake and ion exchange capacity values via its water adsorption and acidification characteristics, respectively. The hydrogen bonding exerted between the surface functional groups of sulfonated magnetite@silica and free water molecules promoted the ion conduction properties of sPVdF membrane. The tortuous pathways and narrower transportation channels of sPVdF/sulfonated magnetite@silica membrane limited the methanol permeation. By the synergetic combination of acidification of polymer and nanocomposite techniques, the existing constrains of PVdF membrane were effectively tackled and the sPVdF/sulfonated magnetite@silica (3 wt%) membrane exhibited the peak power density of 120 mW cm−2 associated with the durability of 150 h at 60 °C, demonstrating the potential applicability of magnetite@silica fillers in DMFCs.
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•Magnetite@silica nanorods were prepared and used as proton conductors.•Sulfonated magnetite@silica nanorods facilitated water uptake of sPVdF membranes.•Silica layer on magnetite nanorods prevented oxidative degradation of membranes.•Nanofillers generated tortuous pathways for methanol permeation.•Acidic moieties and adsorbed water molecules governed high DMFC performances.
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