Ceramics and glasses exhibit unique properties that make them suitable for use in hydrogen-rich environments, particularly in applications such as electrolyzers and sensors. Their performance is influenced by factors such as thermal shock resistance, hydrogen permeation, and chemical stability. Understanding these characteristics is critical for their effective deployment in hydrogen technologies.

Thermal shock resistance is a key consideration for ceramics and glasses in hydrogen systems, where rapid temperature fluctuations are common. Materials like alumina (Al₂O₃) and quartz (SiO₂) demonstrate varying degrees of thermal shock tolerance due to differences in their coefficients of thermal expansion (CTE) and thermal conductivity. Alumina, with a CTE of approximately 8.1 × 10⁻⁶ K⁻¹, exhibits moderate resistance to thermal shock, while fused quartz, with a CTE of 0.55 × 10⁻⁶ K⁻¹, performs better under sudden temperature changes. The low CTE of quartz minimizes stress buildup during heating or cooling, reducing the likelihood of cracking. However, alumina’s higher mechanical strength often makes it preferable in structural applications despite its lower thermal shock resistance compared to quartz.

Hydrogen permeation through ceramics and glasses is another critical factor. Unlike metals, which can suffer from hydrogen embrittlement, ceramics generally have low hydrogen diffusivity. For instance, alumina shows minimal hydrogen permeability, with values typically below 10⁻¹⁴ mol·m⁻¹·s⁻¹·Pa⁻¹ at room temperature. This makes it an effective barrier material in electrolyzers, where preventing hydrogen crossover is essential for efficiency and safety. Quartz, while also resistant to hydrogen permeation, is more commonly used in optical or sensor applications rather than as a barrier due to its brittleness.

In high-temperature electrolysis, ceramics such as yttria-stabilized zirconia (YSZ) are widely used as solid electrolytes in solid oxide electrolyzer cells (SOECs). YSZ exhibits high ionic conductivity for oxygen ions at elevated temperatures (700–1000°C) while remaining impermeable to hydrogen. This property is crucial for maintaining separation between the produced hydrogen and oxygen streams. The material’s stability in reducing and oxidizing atmospheres further enhances its suitability for long-term operation in electrolyzers.

Glasses, particularly silica-based compositions, are employed in hydrogen sensors due to their optical transparency and chemical inertness. Fiber optic sensors using quartz fibers can detect hydrogen leaks by measuring changes in light absorption or refractive index when hydrogen interacts with functionalized coatings. These sensors operate effectively in harsh environments where metal-based sensors might degrade. The lack of electrical conductivity in glasses also eliminates the risk of spark-induced ignition, making them safer for use in explosive atmospheres.

Chemical stability is another advantage of ceramics and glasses in hydrogen-rich environments. Unlike polymers, which can degrade under prolonged exposure to hydrogen, ceramics like alumina and zirconia remain inert. This stability is particularly important in electrolyzers, where acidic or alkaline conditions prevail. For example, alumina components in proton exchange membrane (PEM) electrolyzers resist corrosion even at low pH levels, ensuring durability over thousands of operational hours.

Despite these advantages, challenges remain. The brittleness of ceramics and glasses limits their use in applications requiring mechanical flexibility. Thermal cycling can induce microcracks in alumina over time, gradually reducing its effectiveness as a barrier material. Advances in composite ceramics, such as alumina-toughened zirconia, aim to mitigate these issues by combining high strength with improved fracture toughness.

In sensor applications, the sensitivity and response time of glass-based hydrogen detectors depend on the thickness and composition of the sensing layer. Thin-film coatings of palladium or tungsten oxide on quartz substrates enhance detection capabilities but require precise fabrication to avoid delamination under thermal stress. Research continues to optimize these layers for faster response and greater durability.

The use of ceramics and glasses in hydrogen technologies extends beyond electrolyzers and sensors. For instance, ceramic coatings on metal substrates can provide hydrogen barrier protection in storage tanks, while glass-lined reactors are employed in hydrogenation processes in the chemical industry. The selection of material depends on the specific requirements of the application, balancing factors such as temperature resistance, hydrogen impermeability, and mechanical robustness.

Ongoing research focuses on developing new ceramic compositions with enhanced properties for hydrogen applications. Materials like silicon carbide (SiC) and boron nitride (BN) are being investigated for their high thermal conductivity and resistance to hydrogen permeation. These materials could enable more efficient heat management in high-temperature electrolysis or improve the longevity of hydrogen sensors in aggressive environments.

In summary, ceramics and glasses offer significant advantages in hydrogen-rich environments due to their thermal shock resistance, low hydrogen permeability, and chemical stability. Their use in electrolyzers and sensors highlights their critical role in advancing hydrogen technologies. While challenges related to brittleness and long-term durability persist, material innovations continue to expand their applicability. Future developments in ceramic and glass science will further enhance their performance, supporting the growth of a sustainable hydrogen economy.

The table below summarizes key properties of selected ceramics and glasses in hydrogen applications:

Material CTE (×10⁻⁶ K⁻¹) Hydrogen Permeability (mol·m⁻¹·s⁻¹·Pa⁻¹) Primary Applications
Alumina (Al₂O₃) 8.1 <10⁻¹⁴ Electrolyzers, barriers
Quartz (SiO₂) 0.55 <10⁻¹⁴ Sensors, optical devices
YSZ 10.5 Negligible SOEC electrolytes
Silicon Carbide (SiC) 4.3 Low High-temperature systems

This comparison underscores the importance of material selection based on operational requirements. As hydrogen technologies evolve, ceramics and glasses will remain indispensable components, offering solutions to some of the most demanding challenges in the field.