Au-Pt nanoclusters decorated WS2 nanosheets for achieving highly sensitive NO2 sensing at room temperature

[Display omitted] •One-step liquid exfoliation of Au-Pt nanoclusters decorated WS2 nanosheets without agents.•Outstanding room-temperature sensing performance to ppb-level NO2.•Ultra-low limit of detection of 2.8 ppb.•Combination of experiments and DFT calculations for gas sensing mechanism. Two-dimensional transition metal dichalcogenides (2D TMDs) and their composites are becoming the promising materials for next-generation electronic devices, especially gas sensors, due to their high electronic mobility and room-temperature surface adsorption ability. For exerting these advantages of WS2 nanosheets, we proposed a 0D-0D/2D Au-Pt/WS2 heterostructure composite (i.e, Au-Pt nanoclusters decorated WS2 nanosheets) to boost the gas sensing performance. The Au-Pt/WS2 composite presents outstanding room-temperature NO2 sensitivity to different concentrations of NO2, especially to ppb-level NO2. In particular, the responses of Au-Pt/WS2 composite to 5 and 50 ppb NO2 are 1.23 and 2.00, respectively, with the limit of detection (LOD) of 2.8 ppb. Moreover, the Au-Pt/WS2 composite exhibits good room-temperature reproducibility, selectivity, and long-term stability to NO2. The Au4Pt3 nanocluster is demonstrated to have the lowest binding energy with WS2 by DFT calculations. The outstanding room-temperature NO2 sensitivity of Au-Pt/WS2 composite can be mainly attributed to the formation of Schottky heterojunction and the catalytic activity of Au-Pt nanocluster. This work offers a facile synthesis process of heterogeneous noble metal nanoclusters decorated 2D TMDs, and highlights the outstanding room-temperature gas sensing performance.