Integrating an Ag0–Ag+ mediated Ag2Ta4O11/Ag8(Nb0.5Ta0.5)26O69 heterojunction to quickly decontaminate indoor gaseous formaldehyde under indoor temperature, humidity and sunlight irradiation conditions

Formaldehyde (HCHO) is the primary pollutant indoors, and thus it is essential to establish a feasible proposal to decontaminate HCHO to an acceptable level in terms of human health. Here, using doping and in situ light reduction, a cation vacancy-rich Ag2Ta4O11/Ag8(Nb0.5Ta0.5)26O69 heterojunction is carefully prepared with Ag nanoparticles as cocatalyst. The prepared material is used to photodegrade gaseous HCHO under completely simulated indoor conditions, presenting 100% conversion for 200 ppm and 85.5% for 1600 ppm HCHO under 7 h of sunlight irradiation. Its long-term effectiveness and speed of use were confirmed with six recycling tests under a long 42 h period of sunlight illumination and activity evaluation over a six-month period. Meanwhile, environmental factor estimation confirms its superior CO2 selectivity (99.90%) and humidity resistance. These good performances are ascribed to the Ag0–Ag+ redox electron pairs produced in situ, Nb doping, various interfacial phase interactions and lots of Ag-deficiencies, which contribute to excellent solar light harvesting, quick separation of electron–hole pairs, strong adsorption towards reactive HCHO, maintenance of strong redox ability, and little shedding or aggregation. Consequently, the present sample could be very promising as a long-lasting material for the removal of indoor HCHO.