TiO-modified MoS monolayer films enable sensitive NH sensing at room temperature.

The research and development of high-performance NH sensors are of great significance for environment monitoring and disease diagnosis applications. Two-dimensional (2D) MoS nanomaterials have exhibited great potential for building room-temperature (RT) NH sensors but still suffer from relatively low sensitivity. Herein, the TiO-modified monolayer MoS films with controllable TiO loading contents are fabricated by a facile approach. A remarkable enhancement in the RT NH sensing performance is achieved after the - hetero-compositing of the TiO/MoS system. The device with 95% surface coverage of TiO shows enhanced sensor response, low detection limit (0.5 ppm), wide detection range (0.5-1000 ppm), good repeatability, and superior selectivity against other gases. Kelvin potential force microscopy results revealed that the TiO modification not only improved the surface reactivity of the sensing layers but also contributed to the NH sensing performance by serving as the "gas-gating" layers that modulated the electron depletion layer and the conductivity of the MoS films. Such an - hetero-compositing strategy can provide a simple and cost-effective approach for developing high-performance NH sensors based on 2D semiconductors.