Synergistic Effect of Electron Scattering and Space Charge Transfer Enabled Unprecedented Room Temperature NO2 Sensing Response of SnO2

Abstract Metal oxide gas sensors have long faced the challenge of low response and poor selectivity, especially at room temperature (RT). Herein, a synergistic effect of electron scattering and space charge transfer is proposed to comprehensively improve gas sensing performance of n‐type metal oxides toward oxidizing NO 2 (electron acceptor) at RT. To this end, the porous SnO 2 nanoparticles (NPs) assembled from grains of about 4 nm with rich oxygen vacancies are developed through an acetylacetone‐assisted solvent evaporation approach combined with precise N 2 and air calcinations. The results show that the as‐fabricated porous SnO 2 NPs sensor exhibits an unprecedented NO 2 ‐sensing performance, including outstanding response ( R g / R a = 772.33 @ 5 ppm), fast recovery (<2 s), an extremely low detection limit (10 ppb), and exceptional selectivity (response ratio >30) at RT. Theoretical calculation and experimental tests confirm that the excellent NO 2 sensing performance is mainly attributed to the unique synergistic effect of electron scattering and space charge transfer. This work proposes a useful strategy for developing high‐performance RT NO 2 sensors using metal oxides, and provides an in‐depth understanding for the basic characteristics of the synergistic effect on gas sensing, paving the way for efficient and low power consumption gas detection at RT.