Critical review of hydrogen cyanide (HCN) sensors and their applications

• Hydrogen cyanide (HCN) is extremely toxic in small quantities and used in large quantities across various sectors: chemical synthesis, mining, electroplating, biomarker for diagnosis, weapon of terrorism. • Provides a comprehensive analysis of various gas phase hydrogen cyanide sensor technologies to helps readers choose the appropriate detection method to meet their needs. Hydrogen cyanide (HCN) is a poison gas which can be generated from fuel combustion and conversion from aqueous CN - ions. Approximately 1.1 million metric tons per year of cyanides are utilized by many industries. HCN is also an indicator of air quality, a biomarker for Pseudomonas aeruginosa infection, and a chemical warfare agent. Depending on applications, requirements for HCN sensors significantly vary. In this review, the past and current works on differents HCN gas detection techniques, including optical, mass-based, electrochemical, and chemiresistive sensors, are systematically reviewed. Additionally, it compares various parameters of sensing performance, such as detection range including lower and upper detection limit, sensitivity, selectivity, setup and operation complexity to help the potential users down select the proper type of sensors for their applications. Furthermore, materials computation to discover next generation HCN gas sensing materials is discussed.