Pt Nanoparticle Sensitized PdNi Nanofibers As Highly Sensitive and Selective Hydrogen Gas Sensor

Abstract

Detection of different gases in power transformer oil is essential to accurately examine and understand different problems and faults in the transformer system. Especially, during situations like corona discharge and arcing, evolution of hydrogen gas can be hazardous due to its highly flammable and explosive nature. Therefore, development of high-performance gas sensors targeted for hydrogen gas over a wide range of concentrations is very important.We suggest a facile and effective fabrication method of hydrogen sensing composite material based on palladium and nickel alloy with nanofiber structures originated from electrospinning. PdNi alloy, with further decoration with platinum nanoparticles as catalysts via apo-ferritin templating, shows greatly enhanced sensitivity and response time. Conventionally, Palladium is widely used as hydrogen sensors due to its well-known phase transition to PdHx, α-PdHx at hydrogen concentration below 1%, and β-PdHx at hydrogen concentration above 2%. However, huge volume expansion associated from this transformation limits its lifetime and reduces its long-term performance. In this work, nickel alloying effectively decreases the lattice parameters of the alloy, while increasing the stability during repetitive exposure to high concentration to hydrogen gas. Furthermore, formation of grain boundaries to compensate the lattice contraction induced by nickel alloying, high surface area from its nanofiber structure and gas dissociation and activation properties of platinum nanoparticles improves the sensor’s sensitivity toward hydrogen gas [1]. Nickel in the lattice also acts as pinning points to effectively suppress the grain growth of the alloy during high temperature annealing and reduction processes, which further improves its sensitivity and response time. This facile fabrication and decoration methods allow us to produce a highly sensitive and rapidly responding hydrogen gas sensor with enhanced long-term stability compared to the conventional Pd based hydrogen gas sensors. Reference [1] D. H. Kim, ACS Nano 13, 6071–6082 (2011); doi:10.1021/acsnano.9b02481