Fe-doped CoP nanotube heterostructure enhanced the catalytic activity of Pt nanoparticles towards methanol oxidation reaction

Developing the efficient and stable anode catalysts of direct methanol fuel cell has been a pivotal requirement for its extensive commercial application. Herein, we design the Fe-doped CoP nanotube heterostructure as the co-catalyst of Pt-based catalyst via combining a facile hydrothermal with phosphorization process, subsequently, the traditional NaBH₄ reduction method is utilized to deposit Pt nanoparticles. As anticipated, Fe species have been successfully doped into CoP to generate the Fe-doped CoP nanotube heterostructure, and the involved characterizations identify that Pt–C/Fe₂–CoP catalyst exhibits admirable mass activity (1237 mA·mg⁻¹_Pt) towards methanol oxidation reaction, which is approximately 2.04 and 3.66 times as high as the Pt–C/CoP (607 mA·mg⁻¹_Pt) and Pt–C–H (338 mA·mg⁻¹_Pt). After stability test, the decline ratio of mass activity for Pt–C/Fe₂–CoP (83.43%) is markedly preferable to Pt–C/CoP (94.92%) and Pt–C–H (98.67%) catalysts. The enhanced catalytic activity and durability can be imputed to the formation of uniform Pt nanoparticles and co-catalysis effect of Fe-doped CoP nanotube heterostructure since the introduction of hetero-metal cations is able to effectively accelerate the charge transfer rate and adjust the electronic structure of material. Therefore, the fabrication of nanotube heterostructure and introduction of hetero-metal may provide a new direction to the development of other high-efficiency electrocatalysts.     

Pt-based catalyst decorated by bimetallic FeNi2P with outstanding CO tolerance and catalytic activity for methanol electrooxidation

Subjected to CO poisoning and weak catalytic performance, there are still large barriers to the effective use of direct methanol fuel cells. Therefore, bimetallic FeNi₂P/C hybrid is synthesized by a facile hydrothermal method and low temperature phosphorization process. Subsequently, the as-synthesized FeNi₂P/C is employed as catalytic support to load Pt nanoparticles. Due to the existence of phosphorus and the difunctional effects of Fe and Ni, electrochemical results demonstrate that the prepared Pt–FeNi₂P/C compound exhibits an outstanding catalytic activity of 1125 mA·mg-1 Pt during methanol oxidation in acid solution, tower over that of Pt–FeP₄/C (721 mA·mg^-1_Pt), Pt–Ni₂P/C (588 mA·mg^-1_Pt) and Pt/C-JM (284 mA·mg^-1_Pt), separately. Significantly, bimetallic Pt–FeNi₂P/C hybrid shows the optimal anti poisoning tolerance, which onset potential is negatively shifted 0.2 eV in comparison of Pt/C-JM. Hence, Pt-based catalyst decorated by bimetallic phosphides with excellent anti poisoning tolerance would be a superb material to flourish the catalytic field.     

Bimetallic Pt3Mn nanowire network structures with enhanced electrocatalytic performance for methanol oxidation

Pt-based catalysts are still most attractive and could be the major driving force for facile electrochemical reactions in direct methanol fuel cells (DMFCs). In this work, a Pt₃Mn nanowire network structures (NWNs) catalyst was successfully synthesized by a soft template (CTAB) method. The morphology and elemental composition of the Pt₃Mn NWNs were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and inductively coupled plasma-optical emission spectroscopy (ICP-OES). The electrocatalytic behavior of the synthesized Pt₃Mn NWNs catalyst towards methanol oxidation reaction (MOR) was studied by cyclic voltammetry (CV) and chronoamperometry (CA). The results reveal that the Pt₃Mn NWNs has superior MOR activity and durability compared to Pt NWNs and commercial Pt/C. The mass and specific activities of Pt₃Mn NWNs are 0.843 A mg⁻¹ and 1.8 mA cm⁻² respectively, which are twice that of commercial Pt/C. Additionally, the results of CA test indicate that the Pt₃Mn NWNs possesses better durability than Pt NWNs and commercial Pt/C catalysts in acidic media, which is expected to be a new alternative anode material in DMFCs.     

Platinum-nickel bimetallic catalyst doped with rare earth for enhancing methanol electrocatalytic oxidation reaction

Platinum (Pt) is often used as anodic catalyst for direct methanol fuel cell (DMFC). However, platinum is difficult to achieve large-scale application because of its low stability and high cost. In this work, the electrocatalytic activity and stability of the Pt-based catalyst for methanol oxidation (MOR) are significantly improved by adding Ce and Ni to the catalyst. Additionally, the rare earth element-Pr (Dy) is also chosen to be added into the catalysts for comparison. A series of PtMNi (M = Ce, Pr, Dy) catalysts are prepared by impregnation and galvanic replacement reaction methods using carbon black as support. The electrocatalytic mass activity of PtCeNi/C, PtDyNi/C, PtPrNi/C and Pt/C is 3.92, 1.86, 1.69 and 0.8 A mg_Pt⁻¹, respectively. The mass activity of these the above four catalysts after stability measurement is 3.14, 1.49, 1.27 and 0.72 A mg_Pt⁻¹. Among them, PtCeNi/C has the highest catalytic activity. These as-prepared catalysts are also characterized by various analyzing techniques, such as TEM, HRTEM, XRD, XPS, ICP-OES, STEM, STEM-EDS elemental mapping and line-scanning etc. It shows that PtCeNi/C exhibits best catalytic activity (3.92 A mg_Pt⁻¹) among the as-obtained catalysts, 4.9 times higher than that of commercial Pt/C (0.8 A mg_Pt⁻¹). PtCeNi/C is also with excellent anti-CO poisoning ability. The outstanding catalytic performance of PtCeNi/C for the MOR is mainly attributable to uniform-sized PtCeNi nanoparticles, uniform Ni, Ce and Pt element distribution, and electron interaction among Pt-, Ni- and Ce-related species (electron transferring from Pt to CeO₂).     

Controllable synthesis of efficient Ru-doped PtSn alloy nanoplate electrocatalysts for methanol oxidation reaction

Platinum (Pt) is considered as the preferred metal catalyst for methanol oxidation reactions. However, the application prospects of Pt catalysts are limited due to the inherent scarcity and cost. Enabling a trace amount of Pt to exert satisfactory catalytic activity and durability has become a key issue in designing electrocatalysts. Here, Ru-doped PtSn alloy nanoplates (PtSn@Ru NP) with an average particle size of less than 5 nm were controllably synthesized by adjusting the Pt–Sn atomic ratio. Compared with Ru-doped PtSn alloy nanospheres (PtSn@Ru NS/C, 714.7 mA/mg_Pt), PtSn bimetallic nanoplates (PtSn NP/C, 880.2 mA/mg_Pt) and commercial Pt/C (299.6 mA/mg_Pt), the prepared PtSn@Ru NP/C (1105.1 mA/mg_Pt) exhibited an extraordinary methanol oxidation mass activity. Furthermore, the peak oxidation current retention of PtSn@Ru NP/C was as high as at 87.5% after 1000 accelerated durability tests. The significantly enhanced catalytic performance and durability were attributed to the synergistic effect of the alloy components and morphological advantages. This work has led us to think more deeply about the constitutive relationship between structure and performance.     

Platinum supported on hydroxyl-grafted poly (3,4-ethylenedioxythiophene)-modified RuCo,N-tridoped bamboo-like carbon nanotubes for direct methanol fuel cell

The development of highly active and efficient heterogeneous catalytic oxidation system has become an attractive research field. In this paper, a catalyst (RuCo/N-CNT@PEDOT-OH/Pt) from platinum nanoparticles (Pt NPs) supported on hydroxyl-grafted poly(3,4-ethylenedioxythiophene) (PEDOT–OH)-modified RuCo, N-tridoped bamboo-like carbon nanotubes (RuCo/N-CNT) are used for direct methanol fuel cell (DMFC). The electrocatalytic activity of RuCo/N-CNT@PEDOT-OH/Pt is systematically compared with RuCo/N-CNT/Pt (Pt NPs supported on RuCo/N-CNT without PEDOT-OH) in the methanol oxidation reaction (MOR). The growth mechanism of carbon nanotubes and the role of heteroatom doping in the electrocatalytic process is explored. The catalysts show excellent electrocatalytic performance with high stability for MOR. It is found that the mass activity (MA) of the RuCo/N-CNT@PEDOT-OH/Pt (1961.3 mA mg^?1_Pt) for MOR was higher than that of RuCo/N-CNT/Pt (1470.1 mA mg^?1_Pt) and the commercial Pt/C catalysts (281.0 mA mg^?1_Pt), indicating the positive effect of the PEDOT-OH in the electrocatalytic MOR. In addition, density functional theory (DFT) calculations verify the possible mechanism pathways of the obtained RuCo/N-CNT@PEDOT-OH/Pt catalyst. This presented catalyst offers new inspiration for designing efficient electrocatalysts for methanol oxidation.     

Feasibility of ultra-low Pt loading electrodes for high temperature proton exchange membrane fuel cells based in phosphoric acid-doped membrane

Factors as the Pt/C ratio of the catalyst, the binder content of the electrode and the catalyst deposition method were studied within the scope of ultra-low Pt loading electrodes for high temperature proton exchange membrane fuel cells (HT-PEMFCs). The Pt/C ratio of the catalyst allowed to tune the thickness of the catalytic layer and so to minimize the detrimental effect of the phosphoric acid flooding. A membrane electrode assembly (MEA) with 0.05 mg_Ptcm⁻² at anode and 0.1 mg_Ptcm⁻² at cathode (0.150 mg_Ptcm⁻² in total) attained a peak power density of 346 mW cm⁻². It was proven that including a binder in the catalytic layer of ultra-low Pt loading electrodes lowers its performance. Electrospraying-based MEAs with ultra-low Pt loaded electrodes (0.1 mg_Ptcm⁻²) rendered the best (peak power density of 400 mW cm⁻²) compared to conventional methods (spraying or ultrasonic spraying) but with the penalty of a low catalyst deposition rate.     

Solution plasma method assisted with MOF for the synthesis of Pt@CoOx@N-C composite catalysts with enhanced methanol oxidation performance

The key to direct methanol fuel cells (DMFCs) is the anode catalyst for methanol oxidation reaction (MOR) which has good catalytic activity and stability. Pt@CoO_x@N-C catalysts were synthesized by compounding Pt nanoparticles and CoO_x with nitrogen-doped porous carbon (N-C). Pt nanoparticles were prepared by solution plasma technique. CoO_x@N-C are derived from zeolitic-imidazolate-framework-67 (ZIF-67) by heat treatment at 700 °C. For MOR, Pt@CoO_x@N-C exhibits an outstanding electrocatalytic performance (mass activity of 2400 mA mg_Pt⁻¹) and stability (70% remained after 300 cycles) under acidic condition, which owing to the synergistic effects among the Pt nanoparticles, CoO_x and nitrogen-doped porous carbon. Pt@CoO_x@N-C shows such mass activity superior to that of Pt/C (460 mA mg_Pt⁻¹) due to the fact that CoO can adsorb –OH in the solution and then assist Pt to oxidize the CO-like intermediates to CO₂ which improves the resistance to CO poisoning of Pt nanoparticles. Therefore, solution plasma method assisted with metal-organic frameworks have good development prospects on synthesis of highly efficient electrocatalysts.     

ZIF derived mesoporous carbon frameworks with numerous edges and heteroatom-doped sites to anchor nano-Pt electrocatalyst

We report the use of nitrogen-doped three-dimensional carbon frameworks (N-MCF) to promote the catalytic performance of nano-sized Pt electrocatalyst for the catalysis of oxygen reduction reaction (ORR). The N-MCF, obtained by pyrolysis of zeolitic imidazolate framework, provides abundant edges, defects, and heteroatom-doped sites to anchor Pt nanoparticles, leading to strong Pt-support interaction and excellent particle dispersion within its three-dimensional mass transport channels. Electrochemical results show only 8 mV degradation in the half-wave potential after accelerated durability test for the N-MCF supported Pt catalysts. Meanwhile, the mass activity and specific activity of Pt/N-MFC could reach 246 mA mg⁻¹_Pt and 0.276 mA cm⁻² at 0.90 V_RHE, which is better than that of commercial Pt/C. Moreover, the high Pt utilization of Pt/N-MFC (186 mg _Pt kW⁻¹) could reach 1.9 times than that of fuel cell fabricated with commercial Pt/C cathode.     

Phosphatized pseudo-core-shell Ni@Pt/C electrocatalysts for efficient hydrazine oxidation reaction

In this study, a series of phosphatized pseudo-core-shell Ni@Pt/C electrocatalysts has been obtained for efficient hydrazine oxidation reaction (HzOR). These (Ni@Pt–P/C) electrocatalysts were prepared by a primary replacement method followed by subsequent phosphating process. Among all Ni@Pt–P/C electrocatalysts, as-prepared Ni@Pt–P/C-400 electrocatalyst shows the highest HzOR performance (515 mA mg⁻¹_Pt), best stability, durability and lowest activation energy (12.60 kJ mol⁻¹). The satisfactory HzOR performance is mainly resulted from the unique design of phosphating effect on core-shell structure which producing good synergistic effect between Ni, P and Pt. This work would pave a way for developing other low-Pt catalysts in the future.     

Lattice-strained Pt nanoparticles anchored on petroleum vacuum residue derived N-doped porous carbon as highly active and durable cathode catalysts for PEMFCs

High cost and poor durability of Pt-based cathode catalysts for oxygen reduction reaction (ORR) severely hamper the popularization of proton exchange membrane fuel cells (PEMFCs). Tailoring carbon support is one of effective strategies for improving the performance of Pt-based catalysts. Herein, petroleum vacuum residue was used as carbon source, and nitrogen-doped porous carbon (N-PPC) was synthesized using a simple template-assisted and secondary calcination method. Small Pt nanoparticles (Pt NPs) with an average particles size of 1.8 nm were in-situ prepared and spread evenly on the N-PPC. Interestingly, the lattice compression (1.08%) of Pt NPs on the N-PPC (Pt/N-PPC) was clearly observed by aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), which was also verified by the shift of (111) crystal plane of Pt on N-PPC to higher angles. The X-ray photoelectron spectroscopy (XPS) results suggest that the N-PPC support had a strong effect on anchoring Pt NPs and endowing surface Pt NPs with lowered d band center. Thus, the Pt/N-PPC as a catalyst simultaneously boosted the ORR activity and durability. The specific activity (SA) and mass activity (MA) of the Pt/N-PPC at 0.9 V reached 0.83 mA cm⁻² and 0.37 A mg_Pt⁻¹, respectively, much higher than those of the commercial Pt/C (0.21 mA cm⁻² and 0.11 A mg_Pt⁻¹) in 0.1 M HClO₄. The half-wave potential (E_1/2) of Pt/N-PPC exhibited only a minimal negative shift of 7 mV after 30,000 accelerated durability tests (ADT) cycles. More importantly, an H₂–O₂ fuel cell with a Pt/N-PPC cathode achieved a power density of 866 mW cm⁻², demonstrating that the prepared catalyst has a promising application potential in working environment of PEMFCs.     

Enhanced electrocatalytic property of Pt/C electrode with double catalyst layers for PEMFC

The objective of this study was to fabricate an efficient structural catalyst electrode of Pt/C consisting of double catalyst layers (DCL) with catalyst-ink spray and electrophoresis deposition (EPD) methods. The prepared Pt/C DCL electrode with Pt-dispersed and Pt-concentrated catalyst layers demonstrated better electrochemical properties than individual Pt/C single catalyst layer (SCL) electrodes. An S₁E₁ DCL electrode with Pt loading weight ratio of 1:1 between the Pt-dispersed and Pt-concentrated layers exhibited a higher electrochemical surface area (ECSA, 57.2 m²/g_Pt) and lower internal resistance (20 Ω) than an individual Pt-dispersed SCL electrode prepared with only the spray method (S₁E₀, 31.9 m²/g_Pt and 132 Ω) and an individual Pt-concentrated SCL electrode prepared with only the EPD method (S₀E₁, 34.1 m²/g_Pt and 120 Ω). The S₁E₁ DCL electrode exhibited 2.1 and 1.7 times higher mass activity for methanol oxidation reaction (MOR) than S₁E₀ and S₀E₁ SCL electrodes, respectively (1,230 mA/mg_Pt for S₁E₁ vs. 595 mA/mg_Pt for S₁E₀ and 715 mA/mg_Pt for S₀E₁). In addition, the S₁E₁ DCL electrode demonstrated high MOR durability after 1,000 sequential cycles while losing 30% activity. Meanwhile, S₀E₁ and S₁E₀ SCL electrodes rapidly lost 52% and 55% activity, respectively. These improved electrochemical performances of DCL electrode were owing to the advantages of separating Pt catalysts into two layers, which provides more Pt catalytic active sites to the electrolyte than those in SCL electrodes. Our observation may aid in minimizing the usage amount of Pt catalysts (~0.16 mg_Pt/cm²) compared to those in present commercial Pt/C composites (~0.3 mg_Pt/cm²) as well as maximize efficient Pt utilization. More importantly, with regard to proton exchange membrane fuel cell (PEMFC) activity as a crucial in-situ characterization of a catalyst, a membrane electrode assembly (MEA) containing S₁E₁ as the anode electrode could generate mass maximum power density of 3.84 W/mg_Pt, 3.6 times higher than the present commercial one (1.07 W/mg_Pt).     

Facile one-pot aqueous fabrication of interconnected ultrathin PtPbPd nanowires as advanced electrocatalysts for ethanol oxidation and oxygen reduction reactions

The catalytic features of Pt-based advanced materials closely correlate with the compositions, morphology and structure. Hence, interconnected trimetallic PtPbPd ultrathin nanowires (PtPbPd NWs) were synthesized by octylphenoxypolyethoxyethanol (NP-40)-mediated one-pot aqueous method, using in-situ generated hydrogen bubbles as the dynamic template. It is found that the types of the precursors and the amount of NP-40 are critical in this synthesis. The as-obtained architectures showed remarkable improvement in the electrocatalytic properties for ethanol oxidation reaction (EOR) and oxygen reduction reaction (ORR), surpassing those of commercial Pt/C (20 wt%), homemade PtPd NWs, PtPb NWs and PdPb NWs. Specifically, the mass activity (MA)/specific activity (SA) of PtPbPd NWs (1.20 A mg⁻¹/2.78 mA cm⁻²) is higher than those of Pt/C (0.86 A mg⁻¹/1.79 mA cm⁻²) in 0.5 M KOH solution. Furthermore, the as-synthesized catalyst displayed a positive-shift of the onset potential (E_onset, 0.993 V) for ORR over Pt/C (0.895 V) in 0.1 M KOH electrolyte. These scenarios manifest that this approach provides some new valuable guidelines for preparing novel trimetallic nanocatalysts in energy storage and conversion applications.     

Photodeposition of Pt nanoparticles onto TiO2@CNT as high-performance electrocatalyst for oxygen reduction reaction

The commonly used Pt/C catalyst has low durability for oxygen reduction reaction (ORR). In this work, CNT-supported TiO₂ nanoparticles, which synergistically combines the merits of TiO₂ (high stability and strong interactions with the supported Pt nanoparticles) and CNT (high specific surface area and large electrical conductivity), are prepared by a sol-gel process coupled with an annealing process and used as the support for Pt nanoparticles, which are anchored around TiO₂ nanoparticles by a photodeposition technique. The as-synthesized Pt/TiO₂@CNT catalyst exhibits a mass activity 5.3 times as large as that of the commercial Pt/C catalyst (0.358 A mg_Pt⁻¹ vs. 0.067 A mg_Pt⁻¹ at 0.9 V) and an excellent stability (no activity loss after 10000 potential cycles) for ORR, which can be mainly attributed to the lower oxygen adsorption energy of Pt, resulting from the strong metal-support interaction induced by the deposition of Pt nanoparticles around the well-dispersed TiO₂ nanoparticles on CNT.     

Methoxy methane (dimethyl ether) as an alternative fuel for direct fuel cells

The electrooxidation of methoxy methane (dimethyl ether) was studied at different Pt-based electrocatalysts in a standard three-electrode electrochemical cell. It was shown that alloying platinum with ruthenium or tin leads to shift the onset of the oxidation wave towards lower potentials. On the other hand, the maximum current density achieved was lower with a bimetallic catalyst compared to that obtained with a Pt catalyst. The direct oxidation of dimethoxy methane in a fuel cell was carried out with Pt/C, PtRu/C and PtSn/C catalysts. When Pt/C catalyst is used in the anode, it was shown that the pressure of the fuel and the temperature of the cell played important roles to enhance the fuel cell electrical performance. An increase of the pressure from 1 to 3 bar leads to multiply by two times the maximum achieved power density. An increase of the temperature from 90 to 110 °C has the same effect. When PtRu/C catalyst is used in the anode, it was shown that the electrical performance of the cell was only a little bit enhanced. The maximum power density only increased from 50 to 60 mW cm⁻² at 110 °C using a Pt/C anode and a Pt_0.8Ru_0.2/C anode, respectively. But, the maximum power density is achieved at lower current densities, i.e. higher cell voltages. The addition of ruthenium to platinum has other effect: it introduces a large potential drop at relatively low current densities. With the Pt_0.5Ru_0.5/C anode, it has not been possible to applied current densities higher than 20 mA cm⁻² under fuel cell operating conditions, whereas 250 and almost 400 mA cm⁻² were achieved with Pt_0.8Ru_0.2/C and Pt/C anodes. The Pt_0.9Sn_0.1/C anode leads to higher power densities at low current densities and to the same maximum power density as the Pt/C anode.     

Preparation of PEDOT-modified double-layered hollow carbon spheres as Pt catalyst support for methanol oxidation

In this paper, Pt nanoparticles (Pt NPs) deposited hybrid carbon support is prepared by modifying double-layered hollow carbon spheres（DLHCs）with poly(3,4-ethylenedioxythiophene) (PEDOT) and used as anode catalyst of methanol oxidation. The structure of nanocomposites is characterized by SEM, TEM, FT-IR, XRD and XPS, confirming the greatly enhanced synergistic effect between the PEDOT and DLHCs, and illustrating the uniform distribution of Pt NPs on the PEDOT/DLHCs composite surface with a small particle size (~2.63 nm). Cyclic voltammetry, chronoamperometry and impedance spectroscopy applied to determine the electrocatalytic activity of catalysts, it is found that the synthesized PEDOT/DLHCs/Pt possesses excellent characteristics such as large electrochemically active surface area and high mass activity of 59.45 m² g⁻¹ and 807 mA mg⁻¹ in 0.5 M H₂SO₄ containing 1 M methanol solution, which is almost 1.24 and 2.8 times greater than those of commercial Pt/C, and the catalyst exhibits superior stability after 500 durability cycles. The enhanced electrocatalytic behavior can be ascribed to the excellent electronic conductivity of PEDOT-modified DLHCs and the strong binding of PEDOT/DLHCs to Pt NPs, suggesting that the PEDOT/DLHCs/Pt is a promising electrocatalyst for direct methanol fuel cell.     

Enhanced electrocatalytic activity of PtCu bimetallic nanoparticles on CeO2/carbon nanotubes for methanol electro-oxidation

To achieve the practical application of direct methanol fuel cells, it is highly important to develop effective electrocatalyst with high activity and favorable durability. Herein, we report the successful preparation of PtCu bimetallic nanoparticles supported on ceria/multi-walled carbon nanotubes composite (PtCu–CeO₂/MWCNTs) via microwave-assisted polyol reduction procedure. The composition and morphology of as-obtained composite catalysts were characterized by X-ray diffraction, Raman, X-ray photoelectron spectra, scanning electron microscopy and transmission electron microscopy. The synergistic effects combining PtCu bimetallic effect and oxygen vacancy effect in ceria of such composite catalysts provide abundant active surface area and enhanced conductivity for the effective charge transport during the methanol oxidation reaction (MOR) process. As a results, the PtCu–CeO₂/MWCNTs with optimized Pt proportion achieve greatly enhanced MOR activity with mass activity of 1.28 A mg⁻¹_Pt and specific activity of 2.03 mA cm⁻², superior CO tolerance and reliable stability in contrast to that of commercial Pt/C catalysts.     

Sewage sludge-derived Fe- and N-containing porous carbon as efficient support for Pt catalyst with superior activity towards methanol electrooxidation

In this work, a facile Fe- and N-containing porous carbon derived from sewage sludge was prepared and served as the support of Pt nanoparticles for the electrooxidation of methanol. Both the sludge-derived carbon (denoted as SC) and the resultant Pt/SC catalyst was physically characterized by scanning electron microscope (SEM), transmission electron microscope (TEM) and X-ray diffraction (XRD). The electrocatalytic performance for methanol oxidation reaction (MOR) of the Pt/SC was examined by cyclic voltammetry (CV) and chronoamperometric method. The results showed that the Pt/SC possessed slightly larger Pt particle size (5.5 nm) and lower electrochemical active surface area (ECA) compared to common Pt/C catalyst. However, the mass activity of Pt/SC for MOR was up to 201 mA mg⁻¹, which was much higher than that of Pt/C (93 mA mg⁻¹), indicating the synergistic effect of the sewage sludge-derived carbon with Fe and N species on methanol electrooxidation. Furthermore, Pt/SC showed enhanced durability towards MOR compared to common Pt/C, implying its potential for using in direct methanol fuel cell (DMFC) for energy conversion, which also demonstrated a promising solution for the utilization of sewage sludge resources.     

Experimental investigation on DMFCs using reduced noble metal loading with NiTiO3 as supportive material to enhance cell performances

In this present work, the effect of anode electrocatalyst materials is investigated by adding NiTiO₃ with Pt/C and Pt-Ru/C for the performance enhancement of direct methanol fuel cells (DMFCs). The supportive material NiTiO₃/C has been synthesized first by wet chemical method followed by incorporation of Pt and Pt-Ru separately. Experiments are conducted with the combination of four different electrocatalyst materials on the anode side (Pt/C, Pt-NiTiO₃/C, PtRu/C, Pt-Ru-NiTiO₃/C) and with commercial 20 wt % Pt/C on the cathode side; 0.5 mg_pt/cm² loading is maintained on both sides. The performance tests of the above catalysts are conducted on 5 cm² active area with various operating conditions like cell operating temperatures, methanol/water molar concentrations and reactant flow rates. Best performing operating conditions have been optimized. The maximum peak power densities attained are 13.30 mW/cm² (26.6 mW/mg_pt) and 14.60 mW/cm² (29.2 mW/mg_pt) for Pt-NiTiO₃/C and Pt-Ru-NiTiO₃/C at 80 °C, respectively, with 0.5 M concentration of methanol and fuel flow rate of 3 ml/min (anode) and oxygen flow rate of 100 ml/min (cathode). Besides, 5 h short term stability tests have been conducted for PtRu/C and Pt-NiTiO₃/C. The overall results suggest that the incorporation of NiTiO₃/C supportive material to Pt and Pt-Ru appears to make a promising anode electrocatalysts for the enhanced DMFC performances.     

Effective PtAu nanowire network catalysts with ultralow Pt content for formic acid oxidation and methanol oxidation

Pt is the ideal anode catalyst in fuel cells. In this paper, in order to increase the utilization of Pt, the PtAu nanowire networks (NWNs) with ultralow content of Pt are fabricated by a simple silicon monoxide (SiO) reduction method without any capping agent. PtAu NWNs supported on carbon black with Pt content of 1 wt% (Pt₀.₀₅Au NWNs) are employed as catalysts for formic acid oxidation (FAO) and methanol oxidation reaction (MOR), whose mass activities are as high as 4998.9 and 2282.3 mA∙mg_Pt⁻¹, respectively. The network structure facilitates the electron transfer and increases the stability of the catalysts. The PtAu composite experiences compressive lattice strain as confirmed by X-ray powder diffraction (XRD). The Pt₀.₀₅Au NWNs catalyst with low Pt content results in the largest strain variation compared with PtAu composited of other ratios, which may downshift the d-band center of Pt and lead to the higher electrocatalytic activity in oxidation reaction.