PdPbAg alloy NPs immobilized on reduced graphene oxide/In2O3 composites as highly active electrocatalysts for direct ethylene glycol fuel cells

rGO-modified indium oxide (In2O3) anchored PdPbAg nanoalloy composites (PdPbAg@rGO/In2O3) were prepared by a facile hydrothermal, annealing and reduction method. Electrochemical tests showed that the as-prepared trimetallic catalyst exhibited excellent electrocatalytic activity and high resistance to CO poisoning compared with commercial Pd/C, mono-Pd and different bimetallic catalysts. Specifically, PdPbAg@rGO/In2O3 has the highest forward peak current density of 213.89 mA cm-2, which is 7.89 times that of Pd/C (27.07 mA cm-2). After 3600 s chronoamperometry (CA) test, the retained current density of PdPbAg@rGO/In2O3 reaches 78.15% of the initial value. Its excellent electrocatalytic oxidation performance is attributed to the support with large specific surface area and the strong synergistic effect of PdPbAg nanoalloys, which provide a large number of interfaces and achievable reactive sites. In addition, the introduction of rGO into the In2O3 matrix contributes to its excellent electron transfer and large specific surface area, which is beneficial to improving the catalytic ability of the catalyst. The study of this novel composite material provides a conceptual and applicable route for the development of advanced high electrochemical performance Pd-based electrocatalysts for direct ethylene glycol fuel cells.

Enabling methanol oxidation by interacting hybrid nano system of spinel Co3O4 nanoparticles decorated MXene

For the successful implementation of direct methanol fuel cells in the commercial applications, highly efficient and durable non-noble electrocatalyst based on conducting and stable non-carbonaceous support can be a potential...

An interconnected-graphene enveloped titanium dioxide flower as a robust support for proton exchange membrane fuel cells

A three-dimensional (3D) interconnected-graphene enveloped titanium dioxide flower (TiO2@RGO) as a robust support for the oxygen reduction reaction (ORR) is reported.

Electrochemically active site-rich nanocomposites of two-dimensional materials as anode catalysts for direct oxidation fuel cells: new age beyond graphene

Direct oxidation fuel cell (DOFC) has been opted as a green alternative to fossil fuels and intermittent energy resources as it is economically viable, possesses good conversion efficiency, as well as exhibits high power density and superfast charging. The anode catalyst is a vital component of DOFC, which improves the oxidation of fuels; however, the development of an efficient anode catalyst is still a challenge. In this regard, 2D materials have attracted attention as DOFC anode catalysts due to their fascinating electrochemical properties such as excellent mechanical properties, large surface area, superior electron transfer, presence of active sites, and tunable electronic states. This timely review encapsulates in detail different types of fuel cells, their mechanisms, and contemporary challenges; focuses on the anode catalyst/support based on new generation 2D materials, namely, 2D transition metal carbide/nitride or carbonitride (MXene), graphitic carbon nitride, transition metal dichalcogenides, and transition metal oxides; as well as their properties and role in DOFC along with the mechanisms involved.

Bimetal zeolite imidazolate framework derived Mo0.84Ni0.16-Mo2C@NC nanosphere for overall water splitting in alkaline solution

The bifunctional efficient electrocatalysts for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are in urgent need for the advanced overall water splitting (OWS) device. Restricted by the thermodynamic limitations of the catalytic active center for OER and the reaction kinetics limitations induced by the structure of the electrocatalysts, the development of OWS catalysts requires more effort. Herein, a porous carbon-based bimetal electrocatalyst of Mo_0.84Ni_0.16-Mo₂C@NC nanosphere is prepared by hydrothermal treatment of PMo₁₂@PVP@Zn/Ni-ZIF which is synthesized via one-pot self-assembled hydrothermal method. Our study confirms that the Mo-Ni alloy and Mo₂C nanoparticles homogeneously distribute in nitrogen-rich carbon-based materials. Furthermore, the porous structure exposes rich active sites and increases the effective specific area for redox reactions. The obtained Mo_0.84Ni_0.16-Mo₂C@NC catalyst requires low overpotentials of 151 and 285 mV to reach a current density of 10 mA cm^-2 towards the water reduction and oxidation in 1 M KOH solution, respectively, and possesses good catalytic stability for one day. This work introduces an advanced method for the synthesis of the bimetal electrocatalyst.

Hyperbranched concave octahedron of PtIrCu nanocrystals with high-index facets for efficiently electrochemical ammonia oxidation reaction

Ammonia oxidation reaction (AOR) via electrocatalysis is one of the most efficient ways of utilizing ammonia (a zero-carbon fuel with high hydrogen content) for renewable energy systems. However, AOR seriously suffers from the slow kinetics, and low durability due to its multi-electron transfer process and the poison of the reaction intermediates (N_ads and NO_ads) to precious metal catalysts. Herein, hyperbranched concave octahedral nanodendrites of PtIrCu (HCOND) with high-index facets of {553}, {331} and {221} were developed for the first time using a solvothermal method. The HCOND possesses PtIr-rich edges and exhibit highly efficient AOR activity and stability in alkaline media, wherein their onset potential is 0.35 V vs.RHE, which is 60 mV and 160 mV lower than that of the PtIrCu nanoparticles (NPs) (0.41 V) and commercial Pt/C (0.51 V), respectively, and its high mass activity of 40.6 A g_PtIr^-1 at the 0.5 V vs.RHE is 10.3 times, 2.34 times higher than that of commercial Pt/C (3.9 A g_Pt^-1) and PtIrCu NPs (17.3 A g_PtIr^-1), respectively. In addition, its peak current density (122.9 A g_PtIr^-1) is only reduced by 17.7% after 2000-cycles accelerated durability test. Meanwhile, the performance of PtIrCu HCOND is also better than that of other previously reported morphologies of Pt based catalysts (eg. nanoparticles, nanocubes, nanofilm, nanoflowers). The improvement is critically ascribed to unique advantages of the specific HCOND structure including PtIr rich surface, high-index faceted nanodendrites, strong lattice strain and electronic effects. These characteristics endow the HCOND with great promise to reduce Pt and Ir loading dramatically in the practical application of direct ammonia fuel cells.

One-step fabrication of CuO-doped TiO2 nanotubes enhanced the catalytic activity of Pt nanoparticles towards the methanol oxidation reaction in acid media

To meet the requirements for the potential applications of fuel cells, it is of vital importance to search for advanced electrocatalysts toward the methanol oxidation reaction that have both high electrocatalytic activity and great CO resistance.

Ni2P/rGO/NF Nanosheets As a Bifunctional High-Performance Electrocatalyst for Water Splitting

The hydrogen generated via the water splitting method is restricted by the high level of theoretical potential exhibited by the anode. The work focuses on synthesizing a bifunctional catalyst with a high efficiency, that is, a nickel phosphide doped with the reduced graphene oxide nanosheets supported on the Ni foam (Ni₂P/rGO/NF), via the hydrothermal approach together with the calcination approach specific to the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). The Raman, X-Ray Diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscope (TEM), Scanning Electron Microscopy (SEM), High-Resolution Transmission Electron Microscopy (HRTEM), as well as elemental mapping, are adopted to study the composition and morphology possessed by Ni₂P/rGO/NF. The electrochemical testing is performed by constructing a parallel two-electrode electrolyzer (Ni₂P/rGO/NF||Ni₂P/rGO/NF). Ni₂P/rGO/NF||Ni₂P/rGO/NF needs a voltage of only 1.676 V for driving 10 mA/cm², which is extremely close to Pt/C/NF||IrO₂/NF (1.502 V). It is possible to maintain the current density for no less than 30 hours. It can be demonstrated that Ni₂P/rGO/NF||Ni₂P/rGO/NF has commercial feasibility, relying on the strong activity and high stability.

Ultrafine Pt Nanoparticles Stabilized by MoS2/N-Doped Reduced Graphene Oxide as a Durable Electrocatalyst for Alcohol Oxidation and Oxygen Reduction Reactions

Direct alcohol fuel cells play a pivotal role in the synthesis of catalysts because of their low cost, high catalytic activity, and long durability in half-cell reactions, which include anode (alcohol oxidation) and cathode (oxygen reduction) reactions. However, platinum catalysts suffer from CO tolerance, which affects their stability. The present study focuses on ultrafine Pt nanoparticles stabilized by flowerlike MoS₂/N-doped reduced graphene oxide (Pt@MoS₂/NrGO) architecture, developed via a facile and cost-competitive approach that was performed through the hydrothermal method followed by the wet-reflux strategy. Fourier transform infrared spectra, X-ray diffraction patterns, Raman spectra, X-ray photoelectron spectra, field-emission scanning electron microscopy, and transmission electron microscopy verified the conversion to Pt@MoS₂/NrGO. Pt@MoS₂/NrGO was applied as a potential electrocatalyst toward the anode reaction (liquid fuel oxidation) and the cathode reaction (oxygen reduction). In the anode reaction, Pt@MoS₂/NrGO showed superior activity toward electro-oxidation of methanol, ethylene glycol, and glycerol with mass activities of 448.0, 158.0, and 147.0 mA/mg_Pt, respectively, approximately 4.14, 2.82, and 3.34 times that of a commercial Pt-C (20%) catalyst. The durability of the Pt@MoS₂/NrGO catalyst was tested via 500 potential cycles, demonstrating less than 20% of catalytic activity loss for alcohol fuels. In the cathode reaction, oxygen reduction reaction results showed excellent catalytic activity with higher half-wave potential at 0.895 V versus a reversible hydrogen electrode for Pt@MoS₂/NrGO. The durability of the Pt@MoS₂/NrGO catalyst was tested via 30 000 potential cycles and showed only 15 mV reduction in the half-wave potential, whereas the Pt@NrGO and Pt-C catalysts experienced a much greater shift (Pt@NrGO, ∼23 mV; Pt-C, ∼20 mV).

Quaternized POSS modified rGO-supported Pd nanoparticles as a highly efficient catalyst for reduction and Suzuki coupling reactions

Hydrophilic QPOSS modified rGO nanosheets are fabricated as a robust catalyst support of PdNPs for reduction and Suzuki coupling reactions.

Sophisticated Construction of Binary PdPb Alloy Nanocubes as Robust Electrocatalysts toward Ethylene Glycol and Glycerol Oxidation

The design of nanocatalysts by controlling pore size and particle characteristics is crucial to enhance the selectivity and activity of the catalysts. Thus, we have successfully demonstrated the synthesis of binary PdPb alloy nanocubes (PdPb NCs) by controlling pore size and particle characteristics. In addition, the as-obtained binary PdPb NCs exhibited superior electrocatalytic activity of 4.06 A mg^-1 and 16.8 mA cm^-2 toward ethylene glycol oxidation reaction and 2.22 A mg^-1 and 9.2 mA cm^-2 toward glycerol oxidation reaction when compared to the commercial Pd/C. These astonishing characteristics are attributed to the attractive nanocube structures as well as the large number of exposed active areas. Furthermore, the bifunctional effects originated from Pd and Pb interactions help to display high endurance with less activity decay after 500 cycles, showing a great potential in fuel cell applications.

Green synthesis of Pt–Pd bimetallic nanoparticle decorated reduced graphene oxide and its robust catalytic activity for efficient ethylene glycol electrooxidation

A simple one-pot green synthesis technique is developed to prepare the Pt–Pd bimetallic nanoparticles decorated reduced graphene oxide nanocomposite and its robust catalytic activity for efficient and durable ethylene glycol oxidation is realized.

Facile construction of fascinating trimetallic PdAuAg nanocages with exceptional ethylene glycol and glycerol oxidation activity

Highly open metallic nanocages represent a novel class of nanostructures for advanced catalytic applications in direct liquid fuels cells due to their specific capability of providing easy access to reactants in both internal and external active sites and also desirable electronic structures for the adsorption of molecules, which render superior catalytic performances. However, to date, the rational design of trimetallic nanocages with tunable compositions remains a challenge. Herein, we demonstrate a facile method combining seed mediated and galvanic replacement for the preparation of unique trimetallic Pd-Au-Ag nanocages catalysts with tunable compositions. A series of controlled experiments reveal that the reaction time plays a crucial role in affecting the morphology of the final product. Importantly, the newly-generated Pd-Au-Ag nanocages are high-performance electrocatalysts for the oxidation of both ethylene glycol and glycerol with mass activities of 7578.2 and 5676.1 mA mg^-1, respectively, which are far superior to that of commercial Pd/C. We firmly believe that the strategy and enhanced electrocatalysts developed in this study can be well applied to boost the commercial development of fuel cell technologies.

Electrochemically exfoliated graphene as a novel microwave susceptor: the ultrafast microwave-assisted synthesis of carbon-coated silicon-graphene film as a lithium-ion battery anode

Graphene nanocomposites have attracted much attention in many applications due to their superior properties. However, preparing graphene nanocomposites requires a time-consuming thermal treatment to reduce the graphene or synthesize nanomaterials, in most cases. We present an ultrafast synthesis of a carbon-coated silicon-graphene nanocomposite using a commercial microwave system. Electrochemically exfoliated graphene is used as a novel microwave susceptor to deliver efficient microwave energy conversion. Unlike graphene oxide, it does not require a time-consuming pre-thermal reduction or toxic chemical reduction to absorb microwave radiation efficiently. A carbon-coated silicon nanoparticle-electrochemically exfoliated graphene nanocomposite film was prepared by a few seconds' microwave irradiation. The sp² domains of graphene absorb microwave radiation and generate heat to simultaneously reduce the graphene and carbonize the polydopamine carbon precursor. The as-prepared N-doped carbon-coated silicon-graphene film was used as a lithium-ion battery anode. The N-doped carbon coating decreases the contact resistance between silicon nanoparticles and graphene provides a wide range conductive network. Consequently, it exhibited a reversible capacity of 1744 mA h g^-1 at a current density of 0.1 A g^-1 and 662 mA h g^-1 at 1.0 A g^-1 after 200 cycles. This method can potentially be a general approach to prepare various graphene nanocomposites in an extremely short time.

Ternary hybrid (SPEEK/SPVdF-HFP/GO) based membrane electrolyte for the applications of fuel cells: profile of improved mechanical strength, thermal stability and proton conductivity

Ternary hybrid membranes composed of sulfonated (poly ether ether ketone) (SPEEK), sulfonated polyvinylidene fluoride-co-hexafluoropropylene (SPVdF-HFP) and 1, 3, 5 or 7 wt% graphene oxide (GO) were fabricated using a facile solution casting method.

Facile green synthesis of palladium quantum dots@carbon on mixed valence cerium oxide/graphene hybrid nanostructured bifunctional catalyst for electrocatalysis of alcohol and water

Electrocatalytic oxidation of ethylene glycol at Pd quantum dots@C–CeOx/RGO electrode.