고효율 물 분해를 위한 나노구조 전이금속 촉매의 원소 도핑 연구 = Study on Elemental Doping of Nanostructured Transition-Metal Catalysts for High-Efficiency Water Splitting

다국어 초록 (Multilingual Abstract)

The development of electrocatalysts for water and seawater splitting represents a promising strategy to provide clean and efficient energy, while addressing the inherent limitations of fossil fuels such as resource depletion and environmental pollution. Consequently, the design of cost-effective electrocatalysts with high catalytic efficiency and long-term operational stability, particularly those based on non-precious metals, has become one of the primary objectives of recent research efforts. In this context, this thesis focuses on the rational design and synthesis of advanced transition-metal-based electrocatalysts to achieve efficient and durable overall water splitting.
Firstly, we developed a synthetic strategy to construct a hollow heterostructure NiO/Cr2S3 material through an etching-assisted approach, aiming to enlarge the surface area and enhance interfacial contact. In addition, W single atoms were doped into the NiO/Cr2S3 framework with controlled concentrations to optimize the electronic structure modulation. The resulting material exhibited a large surface area and outstanding electrocatalytic performance toward water splitting. Specifically, W–NiO/Cr2S3 required overpotentials of only 90 mV and 237 mV to achieve a current density of 10 mA cm-2 for the hydrogen evolution reaction and oxygen evolution reaction, respectively. Furthermore, for the overall water splitting process, W–NiO/Cr2S3 achieved a cell voltage of 1.58 V at a current density of 10 mA cm-2.
Secondly, to regulate the electronic structure and enhance charge transfer, as well as to improve the long-term durability of transition metal phosphide catalysts in alkaline media, the multivalent element cerium (Ce) was employed as a dopant. The synergistic interaction among these metal phosphides, together with the Ce-induced electronic modulation, leads to an upward shift of the d-band center toward the Fermi level and a decreased hydrogen adsorption free energy. As a result, the bifunctional Ce-doped (FeCoNi)P catalyst grown on nickel foam (NF) exhibited outstanding overall water-splitting performance, delivering a low cell voltage of 1.42 V at 10 mA cm-2 and maintaining 95 % of its initial activity after 200 h of continuous operation at 100 mA cm-2.

목차 (Table of Contents)

• Chapter 1. Introduction 1
• Chapter 2. Synthesis and Characterization 76
• Chapter 3. Results and Discussion 87
• Chapter 4. Conclusions164
• References 167