Graphene-based electrocatalysts have recently attracted considerable research interest because of the abundant choices they present, with tunable and diverse optical, electronic and chemical ...properties. Furthermore, graphene-based supported materials combine several individual metals to provide a unique platform to create many different electrocatalysts that exhibit new properties for use in different applications. Graphene-based Pt and Pd nanoparticle approaches have been broadly explored and actively pursued to meet those demands to produce excellent electrocatalysts for the methanol oxidation reaction. In this critical review, we highlight the recent developments since 2014 in the controllable synthesis, mechanism, and application of graphene-based Pt and Pd metal electrocatalysts for the methanol oxidation reaction. Finally, some personal intuitions on the main challenges and opportunities in this emerging research field in terms of deep understanding are suggested.
Graphene-based electrocatalysts have recently attracted considerable research interest because of the abundant choices they present, with tunable and diverse optical, electronic and chemical properties.
The synthesis of palladium-based electrocatalysts for alcohol oxidation in half cells and direct alcohol fuel cells is examined. Pd-alloy nanoparticles demonstrated superior activity for alcohol and ...polyalcohol electroxidation.
A porous MoO2 nanosheet as an active and stable bifunctional electrocatalyst for overall water splitting, is presented. It needs a cell voltage of only about 1.53 V to achieve a current density of 10 ...mA cm−2 and maintains its activity for at least 24 h in a two‐electrode configuration.
Developing non‐noble metal catalysts as Pt substitutes, with good activity and stability, remains a great challenge for cost‐effective electrochemical evolution of hydrogen. Herein, ...carbon‐encapsulated WOx anchored on a carbon support (WOx@C/C) that has remarkable Pt‐like catalytic behavior for the hydrogen evolution reaction (HER) is reported. Theoretical calculations reveal that carbon encapsulation improves the conductivity, acting as an electron acceptor/donor, and also modifies the Gibbs free energy of H* values for different adsorption sites (carbon atoms over the W atom, O atom, WO bond, and hollow sites). Experimental results confirm that WOx@C/C obtained at 900 °C with 40 wt% metal loading has excellent HER activity regarding its Tafel slope and overpotential at 10 and 60 mA cm−2, and also has outstanding stability at −50 mV for 18 h. Overall, the results and facile synthesis method offer an exciting avenue for the design of cost‐effective catalysts for scalable hydrogen generation.
Experimental and theoretical studies on carbon‐encapsulated WO
x anchored onto carbon supports, as a remarkable Pt‐like catalyst for the hydrogen evolution reaction are presented. Theoretical calculations reveal that the encapsulated carbon atoms play the key role in improving the conductivity of the materials and modifying the Gibbs free energy of H* values for different adsorption sites.
This
critical review
tersely and concisely reviews the recent development of the polymer electrolyte membranes and the relationship between their properties and affecting factors like operation ...temperature. In the first section, the advantages and shortcomings of the corresponding polymer electrolyte membrane fuel cells are analyzed. Then, the limitations of Nafion membranes and their alternatives to large-scale commercial applications are discussed. Secondly, the concepts and approaches of the alternative proton exchange membranes for low temperature and high temperature fuel cells are described. The highlights of the current scientific achievements are given for various aspects of approaches. Thirdly, the progress of anion exchange membranes is presented. Finally, the perspectives of future trends on polymer electrolyte membranes for different applications are commented on (400 references).
This article reviews the up-to-date advances in the polymer electrolyte membranes, especially for the proton exchange membranes, used for fuel cells.
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•The ultrafine NiCo2S4 nanocores in-situ encapsulated in graphene sheets (GS) with three-dimensional porous networks.•The multicore-shell NiCo2S4@GS nanohybrids were synthesized from ...cation exchange resin precursor.•The mesoporous GS network is formed by thermal decomposition of the pore-forming agent KHCO3.•The advanced button-type NiCo2S4@GS-1||LiFePO4 full battery showed superior cycle stability and practicability.
Bimetallic sulfides were extensively studied as an advanced electrode material for lithium-ion batteries because of their high conductivity and superior capacity compared to metal oxides. We herein have successfully fabricated ultrafine NiCo2S4 nanocores in-situ encapsulated in graphene sheets (NiCo2S4@GS) with three-dimensional porous network structures through a cation adsorption process and subsequent hydrothermal-annealing reaction. In the NiCo2S4@graphene sheets nanohybrids, graphene sheets with abundant mesoporous network structure can be served as a conductive matrix and also be a protective buffer layer to suppress the volume expansion of NiCo2S4 nanoparticles. The NiCo2S4@GS-1 electrodes deliver a high reversible capacity of 813 mAh g−1 upon 200 cycles at 0.2 A g−1, ultralong cycling life of 535 mAh g−1 upon 1000 cycles at 2 A g−1, and excellent rate capability. Additionally, the advanced button-type full batteries were assembled via coupling NiCo2S4@GS-1 anodes with commercial LiFePO4 cathodes showing superior cycle stability and practicability. This work points out an innovative and scalable strategy for preparing composite electrode materials for lithium-ion batteries.
A new one‐step ion‐exchange/activation combination method using a metal‐ion exchanged resin as a carbon precursor is used to prepare a ultrahigh surface area and three‐dimensional hierarchical porous ...graphene‐like networks for fast and highly stable supercapacitors.
Engineering novel Sn‐based bimetallic materials could provide intriguing catalytic properties to boost the electrochemical CO2 reduction. Herein, the first synthesis of homogeneous Sn1−xBix alloy ...nanoparticles (x up to 0.20) with native Bi‐doped amorphous SnOx shells for efficient CO2 reduction is reported. The Bi‐SnOx nanoshells boost the production of formate with high Faradaic efficiencies (>90%) over a wide potential window (−0.67 to −0.92 V vs RHE) with low overpotentials, outperforming current tin oxide catalysts. The state‐of‐the‐art Bi‐SnOx nanoshells derived from Sn0.80Bi0.20 alloy nanoparticles exhibit a great partial current density of 74.6 mA cm−2 and high Faradaic efficiency of 95.8%. The detailed electrocatalytic analyses and corresponding density functional theory calculations simultaneously reveal that the incorporation of Bi atoms into Sn species facilitates formate production by suppressing the formation of H2 and CO.
The first synthesis of homogeneous Sn1−xBix alloy nanoparticles (x up to 0.20) is successfully achieved with native Bi‐atoms‐doped amorphous SnOx nanoshells for highly efficient CO2 reduction into formate, outperforming current tin oxide catalysts.
