Novel sulfur-doped ZnSn(OH)6 nanocubes with induced oxygen vacancies for enhanced humidity sensing

The introduction of defect engineering may increase materials surface redox activity, thereby their sensing properties. Herein, surface defect modulation was achieved by introducing sulfur to induce abundant oxygen vacancies on the surface of ZnSn(OH)6 cubes, which in turn enhanced their humidity sensing performance. Three orders of magnitude in impedance of the S5-ZnSn(OH)6-based humidity sensor was recorded over a relative ambient humidity range of 11 %-95 %, with a response time of 8 s. The sensor also exhibited good linearity, small humidity hysteresis (4.1 %), and long-term stability. The water molecules contact angle of S5-ZnSn(OH)6 sample rapidly decreased to 0 degrees, indicating its stronger excellent hydrophilicity. The adsorption energy of water molecules for S5-ZnSn(OH)6 (-0.827 eV) is more negative than that of the pure one (-0.708 eV), as calculated by using the density functional theory (DFT), revealing a better humidity sensitivity performance of S5-ZnSn(OH)6, which is in agreement with the experimental results. Overall, the proposed sulfur-doped ZnSn(OH)6 humidity sensor was advantageous in terms of simple preparation, low material cost, and good stability performance, thereby promising for future applications.