Nano-Porous UIO-66-NH₂/TiO₂ Bragg Reflector for Low Concentration HCl Gas Sensing

Highly sensitive, selective, and repetitive real-time detection of the low concentration (<; 5ppm) HCl gas is crucially important in environmental protection and industrial safety. In this paper, we proposed a nano-porous UIO-66-NH
₂
/TiO
₂
Bragg reflector sensor and investigated its sensing properties for 0~3ppm HCl gas. The UIO-66-NH
₂
/TiO
₂
Bragg reflector sensor exhibits a high sensitivity of the reflectance intensity response to be 1.19%/ppm with a good linear relationship in the concentration range of 0~3ppm HCl, and a fast optical response and recovery time of 1s and 8s. The effect of the temperature (T) and relative humidity (%RH) on the sensing sensitivity were also studied and discussed. Moreover, the excellent selectivity of the UIO-66-NH
₂
/TiO
₂
Bragg reflector sensor for detection among HCl and CCl
₄
, CH
₂
Cl
₂
, N
₂
, CO
₂
gas/vapor was validated by the value of S (Response(HCl) / Response(vapor)) tested to be more than 8. Furthermore, the UIO-66-NH
₂
/TiO
₂
Bragg reflector sensor presents exceptional reversibility and reliability by different test treatments, which demonstrating its high potential for detection application of low concentration HCl gas.