Designing highly sensitive formaldehyde sensors via A-site cation deficiency in LaFeO₃ hollow nanofibers

In this work, a facile strategy to improve the formaldehyde (HCHO) sensing performance via introducing A-site cation deficiency of LaFeO₃ hollow oxides is reported. One-dimensional La_xFeO₃ hollow nanofibers (L_xFO HNFs, x = 1.0, 0.9, 0.8, 0.7, and 0.6) were prepared through electrospinning technique and subsequent calcination treatment. Benefiting from the hollow nanostructures and the existed A-site cation deficiency in L_xFO HNFs, all the rapid charge transfer, abundant oxygen vacancies, and chemisorbed active sites could be achieved. Among all these L_xFO HNFs sensors, the non-stoichiometric L_0.7FO HNFs sensor delivered a high response value of 20.4 towards 100 ppm HCHO at 180 °C, which is over 3-fold higher than that of stoichiometric L_1.0FO HNFs (6.3). Moreover, L_0.7FO HNFs sensor has virtues of rapid response/recovery speed (23 /13 s), high selectivity, and good long-term stability toward HCHO. The smart HCHO detection device assembled with the L_0.7FO HNFs gas sensor also enabled real-time and visible HCHO monitoring, highlighting its great potential application in the smart detection of hazardous gases.