High-Resolution Pd-Ni Hydrogen Gas Sensor Capable of Detection Ultra- High Purity Hydrogen

Hydrogen (H₂) has different types of impurities depending on the production method, which determines the purity of hydrogen. For hydrogen to be used as a fuel for a hydrogen fuel cell vehicle, the purity of hydrogen is very important. Low-purity hydrogen containing several impurities adversely affects the catalyst of the fuel cell and greatly reduces the lifespan of the fuel cell system. Gas Chromatography (GC) used in the field is a method of periodically extracting and measuring hydrogen gas, so it is impossible to check in real-time. Therefore, a hydrogen sensor capable of measuring high-purity hydrogen of 90% or more is necessary.<br/><br/>For the hydrogen sensor of the Delta Resistance type, it is important to secure a resolution capable of discriminating the difference in resistance between the measured hydrogen concentrations when measuring the hydrogen concentration. In addition, palladium (Pd) used as a hydrogen detection material has structural instability in a high concentration of hydrogen when used alone.<br/><br/>In this study, a multi-layered alloy catalyst of Pd and Ni was prepared using nickel (Ni) as complementary material to Pd. The core technology of the ultra-high concentration hydrogen sensor is to control the distribution density of the alloyed Pd-Ni catalyst metal layer to secure the hydrogen concentration resolution characteristics. A structurally optimized hydrogen sensor was fabricated by implementing the digit form.<br/><br/>The hydrogen detection layer manufacturing method uses an E-beam evaporator to deposit Pd-Ni, a catalyst metal for H₂ dissociation reaction, on a SiO₂ substrate in the form of a Pd/Ni/Pd sandwich type multilayer thin film. The Pd-Ni sensor was measured at various ultra-high hydrogen concentrations of 90-100% containing impurity gas.<br/><br/>The manufactured hydrogen sensor secured 0.1-1% resolution at high hydrogen concentration and showed excellent performance in detecting hydrogen within 5 seconds. This is thought to be because Ni acted as a co-catalyst in the Pd-Ni double-layer catalyst, resulting in a change in hydrogen adsorption/desorption reaction energy, and the digit structure increased the base resistance.