Promoting effects of Fe 2 O 3 to Pt electrocatalysts toward methanol oxidation reaction in alkaline electrolyte

Polythiophene-coated carbon nano boxes for efficient platinum-based catalysts for methanol electrooxidation

To improve the efficiency of the methanol oxidation reaction (MOR) in direct methanol fuel cells (DMFCs), it is essential to develop catalysts with high catalytic activity. However, constructing polyatomic doped carbon nanomaterials and understanding the interaction mechanisms between dopant elements remain significant challenges. In this study, we propose nitrogen-doped carbon nanobox (CNB) derived from Zeolitic Imidazolate Framework-67 (ZIF-67) crystals as precursors to serve as carriers for highly efficient platinum nanoparticles (Pt NPs). We synthesized platinum/poly(3,4-propylenedioxythiophene)/carbon nanobox (Pt/PProDOT/CNB) composites by wrapping CNB around PProDOT films via in situ oxidative polymerization. This unique structural design provides several advantages to the catalyst, including a large active surface area, numerous accessible electrocatalytic active centers, an optimized electronic structure, and good electronic conductivity. The Pt/PProDOT/CNB composites demonstrated excellent methanol oxidation performance, with a remarkable mass activity (MA) of 1639.9 mA mg-1Pt and a high electrochemical active surface area (ECSA) of 160.8 m2/g. Furthermore, the catalyst exhibited good CO resistance and outstanding durability.

Elucidating the effects of nitrogen and phosphorus co-doped carbon on complex spinel NiFe2O4 towards oxygen reduction reaction in alkaline media

The study presents for the first time complex spinel NiFe2O4 nanoparticles supported on nitrogen and phosphorus co-doped carbon nanosheets (NPCNS) prepared using sol gel and the carbonization of graphitic carbon nitride with lecithin as a highly active and durable electrocatalyst for oxygen reduction reaction. The physicochemical properties of complex spinel NiFe2O4 on NPCNS and subsequent nanomaterials were investigated using techniques such as X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and transmission electron microscopy. The electrochemical activity of the electrocatalysts was evaluated using hydrodynamic linear sweep voltammetry, cyclic voltammetry, electrochemical impedance spectroscopy, and chronoamperometry. The electrocatalytic performance of the NiFe2O4/NPCNS nanohybrid electrocatalyst is dominated by the 4e- transfer mechanism, with an onset potential of 0.92 V vs. RHE, which is closer to that of the Pt/C, and a current density of 7.81 mA/cm2 that far exceeds that of the Pt/C. The nanohybrid demonstrated the best stability after 14 400 s, outstanding durability after 521 cycles, and the best ability to oxidize methanol and remove CO from its active sites during CO tolerance studies. This improved catalytic activity can be attributed to small nanoparticle sizes of the unique complex spinel nickel ferrite structure, N-Fe/Ni coordination of nanocomposite, high dispersion, substantial ECSA of 47.03 mF/cm2, and synergy caused by strong metal-support and electronic coupling interactions.

Glycerol Electro-Oxidation in Alkaline Medium with Pt-Fe/C Electrocatalysts Synthesized by the Polyol Method: Increased Selectivity and Activity Provided by Less Expensive Catalysts

We have investigated platinum catalysts containing iron as a modifier to obtain catalysts with superior electrocatalytic activity toward glycerol electro-oxidation in an alkaline medium. The electrocatalysts, supported on carbon Vulcan, were synthesized by the polyol method. The physicochemical characterization data showed that the metals were well distributed on the carbon support and had small particle size (2 nm). The Pt:Fe metal ratio differed from the nominal composition, indicating that reducing iron with platinum was difficult, even though some parameters of the synthesis process were changed. Electrochemical analyses revealed that PtFe/C was more active and stable than commercial Pt/C was, and analysis of the electrolysis by-products showed that iron addition to Pt/C boosted the glycerol conversion and selectivity for glyceric acid formation.

Reduced graphene oxide (RGO)-supported Pd–CeO2 nanocomposites as highly active electrocatalysts for facile formic acid oxidation

Reduced graphene oxide (RGO)-supported Pd–CeO2 nanoparticles prepared by a chemical reduction method were shown to exhibit superior electrocatalytic activity towards formic acid compared to the commercial Pd/C catalyst.

Engineering intermetallic-metal oxide interface with low platinum loading for efficient methanol electrooxidation

Constructing a distinctive electrochemical interface with low platinum content to boost the sluggish methanol electrooxidation kinetics is critical for commercializing the direct methanol fuel cells. Herein, we have synthesized highly active electrocatalysts with unique intermetallic-metal oxide interfaces through a facile pyrolysis method. Physical characterizations demonstrate that the obtained PtFe^(1:2)@a-FeO_x/NC-C catalyst with low platinum content of 7.2 wt% possesses an interfacial structure composed of face-centered tetragonal (L1₀) PtFe intermetallic nanoparticles accompanied with amorphous iron oxide. Electrochemical measurements show that the synthesized PtFe^(1:2)@a-FeO_x/NC-C catalyst not only exhibits excellent methanol electrooxidation activities with a mass activity of 1.48 A mg^-1_Pt and a specific activity of 2.34 mA cm^-2_Pt in acid medium, but also possesses better CO-tolerant performance and faster methanol oxidation kinetics compared with commercial Pt/C. The improved electrochemical performances may ascribe to the modified electronic structure by alloying platinum with iron and the special PtFe@a-FeO_x interface, which render strong synergistic interactions between bimetallic PtFe nanoparticles and amorphous iron oxide. Consequently, the presented strategy offers new prospects into the construction of low-cost electrocatalysts with unique electrochemical interface for enhancing catalytic performances.

3D structured Mn2O3 synthesized using tween surfactant: influence on the morphology and oxygen reduction catalytic performance

Tween-80 affects the oxygen vacancies of Mn₂O₃, boosting its oxygen storage capability and electron transfer rate for ORR.