Luận án tiến sĩ kỹ thuật hóa học synthesis and characterization of m doped tio2

Low-temperature fuel cell systems offer high energy efficiency. They present near-zero emissions. Fuel cells can reduce fossil fuel reliance. Electrocatalysts are crucial for fuel cell performance. Carbon-supported platinum catalysts are common. They face significant limitations. Poor durability is a major issue. Carbon corrosion occurs. This leads to sintering and agglomeration of Pt nanocatalysts. Slow kinetics for fuel oxidation also present a problem. Oxygen reduction reaction (ORR) is sluggish. CO poisoning affects active platinum sites. This happens even at low CO concentrations (< 5 ppm). Long-term operation suffers performance deterioration. Developing robust electrocatalysts remains a challenge. This hinders fuel cell commercialization. Solving fuel cell problems requires new approaches. Non-carbon materials offer promise. They serve as alternative catalyst supports. These materials show superior corrosion resistance. They perform well in electrochemical media. Strong interaction with Pt nanocatalysts is observed. This interaction enhances catalytic activity. It also improves stability of Pt-based catalysts. Titanium dioxide (TiO2) stands out among carbon-free supports. It possesses superior electrochemical stability. TiO2 is non-toxic and affordable. A strong metal-support interaction (SMSI) exists. This synergistic effect enhances activity and durability. Intrinsic low electrical conductivity limits TiO2 application. This is a major hindrance.

1.1. Challenges of Carbon Supported Platinum Catalysts

1.2. The Need for Robust Non Carbon Supports

Titanium dioxide (TiO2) is a compelling material. It serves as a support for fuel cell catalysts. Its benefits include exceptional electrochemical stability. The material is non-toxic. Its affordability makes it attractive. A strong metal-support interaction occurs. This interaction with platinum nanocatalysts boosts performance. It enhances both electrocatalytic activity and durability. This makes TiO2 a valuable component. Its use can improve overall fuel cell efficiency. However, a significant drawback exists. TiO2 has inherently low electrical conductivity. This property restricts its broader application. Overcoming this limitation is essential. The low electrical conductivity of TiO2 presents a challenge. A doping strategy addresses this issue. Transition metals are introduced into the titania structure. This approach is highly effective. It enhances the electronic conductivity of TiO2. The strategy also improves electrochemical activity. Durability of Pt-based catalysts increases significantly. This is critical for fuel cell applications. The doping method is recognized as the best solution. It allows for advanced use of TiO2. This makes it a more viable support material. This research explores specific doping elements. Platinum nanocatalysts combine with M-doped TiO2 supports. M represents tungsten (W) and iridium (Ir). These supports are successfully synthesized. A one-pot synthesis method is employed. This process requires no surfactants or stabilizers. It also avoids further heat treatment. This simplifies the preparation. The goal is to create robust electrocatalysts. These materials are 20 wt. % Pt/M-doped TiO2 (M=W, Ir). Experimental results show promise. These electrocatalysts are suitable for low-temperature fuel cells. They can function at both anodic and cathodic electrodes.

2.1. Advantages of Titanium Dioxide as a Support Material

2.2. Doping Strategy to Overcome TiO2 Limitations

2.3. M doped TiO2 W and Ir as Doping Elements

The synthesis of M-doped TiO2 (M=W, Ir) supports is critical. A one-pot method is employed. This approach simplifies the fabrication process. It eliminates the need for surfactants or stabilizers. Further heat treatment is also unnecessary. This method contributes to cost-effectiveness. It also promotes manufacturing efficiency. This synthesis strategy ensures uniform doping. It allows for precise control over material properties. The resulting M-doped TiO2 materials provide a stable base. They effectively support platinum nanocatalysts. This streamlined synthesis is a key innovation. It facilitates the development of advanced fuel cell materials. A novel Pt catalyst is prepared. It is supported on mesoporous Ti0.3O2. This material exhibits high conductivity (2 Ω.cm⁻¹). It also boasts a large specific surface area (201 m².g⁻¹). The preparation occurs via a rapid microwave-assisted polyol route. This method is successful. Uniform 3 nm spherical-like Pt nanoparticles adhere. They are homogeneously distributed on the Ti0.3O2 surface. This specific synthesis technique is innovative. It optimizes the support's properties. High conductivity and large surface area are achieved. These features are vital for catalytic performance. The microwave assistance speeds up the reaction. It ensures uniform heating and crystal growth. This results in highly efficient electrocatalysts.

3.1. One Pot Synthesis of M Doped TiO2 Supports

3.2. Microwave Assisted Polyol Route for Ti0.3O2

The electrochemical surface area (ECSA) is a key metric. The 20 wt. % Pt/Ti0.3O2 catalyst shows exceptional results. Its ECSA is approximately 90 m².g⁻¹Pt. This figure is significantly higher. It surpasses that of commercial 20 wt. % Pt/C. This indicates more active platinum sites are available. The uniform dispersion of Pt nanoparticles contributes to this. The mesoporous structure of the support also plays a role. A larger ECSA means more contact points for reactions. This leads to improved catalytic efficiency. The enhanced surface area is a direct benefit. It results from the novel support material. Methanol oxidation reaction (MOR) performance is evaluated. The ratio of forward peak current to backward peak current (If/Ib) is measured. The 20 wt. % Pt/Ti0.3O2 catalyst performs remarkably well. Its If/Ib ratio is about 2.5-fold higher. This is compared to commercial 20 wt. % Pt/C. A higher If/Ib ratio indicates improved MOR activity. It also suggests better tolerance to intermediate poisoning. This is crucial for direct methanol fuel cells. The doped TiO2 support enhances Pt activity. This leads to more efficient methanol conversion. Durability is a critical factor for fuel cells. Chronoamperometry data confirms this. The 20 wt. % Pt/Ti0.3O2 catalyst exhibits higher durability. It outperforms commercial 20 wt. % Pt/C. The catalyst also shows better CO-poisoning tolerance. This is vital for long-term operation. The strong interaction (SMSI) between Pt and M-doped TiO2 causes this. Weak adsorption of carbonaceous species occurs. This prevents active site blockage. The catalyst's activity and stability for MOR increase. This is highly beneficial for direct methanol fuel cell applications.

4.1. Superior Electrochemical Surface Area of Pt Ti0.3O2

4.2. Improved Methanol Oxidation Reaction MOR Performance

4.3. Enhanced Durability and CO Poisoning Tolerance

The strong metal-support interaction (SMSI) is paramount. This phenomenon occurs between Pt and M-doped TiO2 supports. It creates a synergistic effect. This interaction significantly enhances electrocatalytic activity. It also boosts the durability of the electrocatalyst. The SMSI alters the electronic properties of platinum. It facilitates weak adsorption of carbonaceous species. This prevents poisoning of active sites. The interaction ensures the catalyst remains active. It prolongs the lifespan of the fuel cell. Understanding SMSI is key to designing superior catalysts. This thesis demonstrates its profound impact. The findings hold significant implications. Robust electrocatalysts are essential. They enable further commercialization of fuel cell technologies. The developed Pt/M-doped TiO2 materials offer a solution. They address key challenges like durability and activity. The novel Ti0.3O2 support shows great promise. Its high conductivity and surface area are beneficial. The enhanced MOR activity and CO tolerance are critical. This research contributes to cleaner energy solutions. It moves fuel cell technology closer to widespread adoption. This work paves the way for more efficient and stable fuel cell systems.

5.1. Strong Metal Support Interaction SMSI Effects

5.2. Future Implications for Fuel Cell Commercialization