Dog nose-inspired high-performance ammonia sensor based on biochar/SnO2 composite

Inspired by the ordered tubular structure inside the dog nose and its olfactory receptors, this paper reports a biochar/SnO2 composite based on waste disposable bamboo chopsticks (DBC) combined with tin dioxide (SnO2) nanoparticles. The response of optimized biochar/SnO2 composite reaches 4513 to 500 ppm NH3, and the response/recovery times are 50.4 s and 3.7 s, respectively. The biochar/SnO2 composite displays the dog-nose-like ultra-fast response (1 s response up to 1100) to 500 ppm NH3 at room temperature (25 °C), which makes the biochar/SnO2 composite with the application promising for rapid detection of NH3. The optimized biochar/SnO2 sensor also exhibits good selectivity and linear response with a theoretical detection limit as low as 34 ppb NH3. In addition, the biochar/SnO2 sensor has reliable humidity immunity and long-term stability. Within a period of up to six months, the response fluctuation of biochar/SnO2 sensor to 500 ppm NH3 at 25 °C is less than 3.7%. However, the susceptibility of biochar/SnO2 composite to the operating temperature need to be overcome. The biochar/SnO2 composite was prepared by low-temperature pyrolytic carbonization (300 °C) with the advantages of abundant raw materials, low cost and green environmental protection, providing a new outlet for solid waste.