Synthesis of Bimetallic Pt3Co Alloy Nanocrystals for Heterogeneous Hydrogenation of CO2 to Methanol

Inhaltsverzeichnis (Table of Contents)

• Chapter 1. Introduction
• 1.1 Motivation and General Background
• 1.2 CO2 Properties
• 1.3 Industrial Applications of CO2 Conversion
• 1.4 Strategies for Minimizing CO2 Concentration
• 1.4.1 Establishing Renewable Energy
• 1.4.2 Carbon Capture and Sequestration
• 1.4.3 Carbon Capture and Recycling
• 1.4.4 Hydrogenation of CO2 to CH3OH
• 1.5 Strategies to Modify Electronic Properties of Heterogeneous Catalyst
• 1.5.1 Heterogeneous Catalysis
• 1.5.2 Shape Controlled Synthesis of Heterogeneous Catalyst
• 1.5.3 Bimetallic Nanocrystals
• 1.5.4 Alloys
• 1.5.5 Core Shell Nanocrystals
• 1.5.6 Multipods and Nanodendrites
• 1.6 Aims and Research Objectives
• 1.6.1 Aims
• 1.6.2 Research Objective
• Chapter 2. Synthesis, Characterization and Mechanism of CO2 Hydrogenation
• 2.1 Material Synthesis Routes
• 2.1.1 Coreduction
• 2.1.2 Thermal Decomposition
• 2.1.3 Seed Mediated Growth
• 2.1.4 Galvanic Replacement
• 2.2 Chemicals and Materials
• 2.3 Characterization Techniques
• 2.4 Mechanism of CO2 Hydrogenation to CH3OH
• Chapter 3. Pt3Co Octapods as Superior Catalyst of CO2 Hydrogenation
• 3.1 Introduction
• 3.2 Experimental Section
• 3.3 Results and Discussion
• 3.4 Summary

Zielsetzung und Themenschwerpunkte (Objectives and Key Themes)

This dissertation investigates the synthesis of bimetallic Pt3Co alloy nanocrystals as highly efficient catalysts for the heterogeneous hydrogenation of CO2 to methanol. The main objective is to improve the catalytic activity and selectivity of this reaction by modifying the electronic properties of the catalyst through shape control and alloying.

• The synthesis and characterization of bimetallic Pt3Co nanocrystals with controlled shapes.
• The investigation of the relationship between catalyst structure (shape and composition) and catalytic activity.
• The elucidation of the reaction mechanism for CO2 hydrogenation to methanol using these catalysts.
• The exploration of the role of electronic properties in the catalytic process.
• The evaluation of the long-term stability and reusability of the developed catalysts.

Zusammenfassung der Kapitel (Chapter Summaries)

Chapter 1. Introduction: This chapter introduces the critical need to address rising CO2 levels due to fossil fuel combustion. It highlights the environmental impact of CO2 emissions and explores various strategies to mitigate these effects, including renewable energy, carbon capture and sequestration, and carbon capture and recycling. The chapter focuses on the advantages of CO2 hydrogenation to methanol as a sustainable fuel source and discusses methods for modifying catalyst electronic properties, such as shape control and bimetallic alloying, to optimize the catalytic process. The chapter concludes by outlining the aims and objectives of the dissertation.

Chapter 2. Synthesis, Characterization and Mechanism of CO2 Hydrogenation: This chapter details the synthesis methods employed for creating bimetallic nanocrystals, including coreduction, thermal decomposition, seed-mediated growth, and galvanic replacement. It provides a thorough description of the advanced analytical characterization techniques used (e.g., FT-IR, XRD, UV-Vis, SEM, TEM, XPS, ICP-AES, NMR) to analyze the structure and composition of the synthesized nanocrystals. The chapter also delves into the proposed mechanisms of CO2 hydrogenation to methanol, discussing various pathways and the role of intermediates.

Chapter 3. Pt3Co Octapods as Superior Catalyst of CO2 Hydrogenation: This chapter presents the synthesis and catalytic testing of Pt3Co nanocrystals, focusing on the superior activity of octapod-shaped nanocrystals. The chapter details the experimental procedures for the synthesis of Pt, Pt3Co nanocubes, and Pt3Co octapods, including characterization using TEM, HAADF-STEM, XRD, XPS, and in situ DRIFTS. The results demonstrate the significantly higher catalytic activity of Pt3Co octapods in CO2 hydrogenation to methanol compared to other nanostructures. DFT calculations are used to explain the enhanced activity by analyzing the charge distribution and the role of the sharp-tip and alloy effects in promoting CO2 activation.

Schlüsselwörter (Keywords)

Carbon dioxide, hydrogenation, methanol, platinum, cobalt, bimetallic nanocrystals, catalyst, octapods, electronic properties, charge transfer, DFT calculations, heterogeneous catalysis, renewable energy.

Häufig gestellte Fragen

What is the main topic of this document?

This document provides an overview of a research dissertation focused on using bimetallic Pt3Co alloy nanocrystals as catalysts for the hydrogenation of CO2 to methanol.

What are the key objectives of the research?

The main objectives are to improve the catalytic activity and selectivity of CO2 hydrogenation to methanol by modifying the electronic properties of the catalyst through shape control (specifically using octapod nanocrystals) and bimetallic alloying of Platinum and Cobalt.

What strategies are explored to minimize CO2 concentration?

The strategies explored include: establishing renewable energy, carbon capture and sequestration, carbon capture and recycling, and hydrogenation of CO2 to CH3OH (methanol).

What methods are used for synthesizing bimetallic nanocrystals?

The synthesis methods include: coreduction, thermal decomposition, seed-mediated growth, and galvanic replacement.

What characterization techniques are used to analyze the synthesized materials?

The dissertation utilizes various characterization techniques, including FT-IR, XRD, UV-Vis, SEM, TEM, XPS, ICP-AES, and NMR to analyze the structure and composition of the synthesized nanocrystals.

What is the significance of using Pt3Co octapods as catalysts?

Pt3Co octapods demonstrate superior catalytic activity in CO2 hydrogenation to methanol compared to other nanostructures due to their unique shape and alloy composition, which enhance CO2 activation.

What role do electronic properties play in the catalytic process?

The electronic properties of the catalyst, modified through shape control and alloying, influence the charge distribution and affect the activation of CO2 molecules, thus impacting the catalytic activity.

What topics are covered in Chapter 1 (Introduction)?

Chapter 1 introduces the need to reduce CO2 levels, highlights the environmental impact of CO2 emissions, explores mitigation strategies (renewable energy, carbon capture), and focuses on CO2 hydrogenation to methanol. It also discusses methods for modifying catalyst electronic properties and outlines the dissertation's aims and objectives.

What topics are covered in Chapter 2 (Synthesis, Characterization and Mechanism of CO2 Hydrogenation)?

Chapter 2 details the synthesis methods for bimetallic nanocrystals, describes the advanced analytical characterization techniques used, and explores the proposed mechanisms of CO2 hydrogenation to methanol.

What topics are covered in Chapter 3 (Pt3Co Octapods as Superior Catalyst of CO2 Hydrogenation)?

Chapter 3 presents the synthesis and catalytic testing of Pt3Co nanocrystals, focusing on the superior activity of octapod-shaped nanocrystals. It includes experimental procedures, characterization results, and DFT calculations to explain the enhanced activity.

What are some of the keywords related to this research?

Keywords include: Carbon dioxide, hydrogenation, methanol, platinum, cobalt, bimetallic nanocrystals, catalyst, octapods, electronic properties, charge transfer, DFT calculations, heterogeneous catalysis, renewable energy.