Hydrogen (H2), as a source of energy, continues to be a compelling choice in applications ranging from fuel cells and propulsion systems to feedstock for chemical, metallurgical and other industrial processes. H2, being a clean, reliable, and affordable source, is finding ever increasing use in distributed electric power generation and H2 fuelled cars. Although still under 0.1%, the distributed use of H2 is the fastest growing area. In distributed H2 storage, distribution, and consumption, safety continues to be a critical aspect. Affordable safety systems for distributed H2 applications are critical for the H2 economy to take hold. Advances in H2 sensors are driven by specificity, reliability, repeatability, stability, cost, size, response time, recovery time, operating temperature, humidity range, and power consumption. Ambient temperature sensors for H2 detection are increasingly being explored as they offer specificity, stability and robustness of high temperature sensors with lower operational costs and significantly longer operational lifetimes. This review summarizes and highlights recent developments in room temperature H2 sensors.
