Ordered porous BiVO₄ based gas sensors with high selectivity and fast-response towards H₂S

Seeking for novel materials that show pronounced gas sensing performance has been of great interests from both academic and technological perspectives. Herein, we report for the first time the gas sensing properties of monoclinic phase BiVO₄ porous films with high selectivity and low detection limit towards H₂S. The porous film with honeycomb-like morphology was in situ synthesized based on the solution dipping strategy using monolayer colloidal crystal as template. The BiVO₄ porous film based sensor exhibits excellent sensing performance with high selectivity of 15.9 and the response time as fast as 5 s toward 25 ppm H₂S gas at low working temperature (75 °C). The sensing detection limit can reach as low as 62.5 ppb. Moreover, the general feature of the colloidal crystal template approach allows for the accessing of porous BiVO₄ films based gas sensors with tunable sensing performance. Based on a five-axe spider-web diagram which could evaluate the optimal practical work condition including sensitivity, selectivity, operating temperature and response/recovery rate, the porous film with 200 nm pore size demonstrates the best potential to keep the good balance of sensing performance. These results suggest that BiVO₄, which is a well-known photocatalyst, can be potentially used in high performance gas sensing.