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Bimetal decoration on ZnO-based sensing materials can effectively improve their sensing performance, while the synergistic effect and structure-activity relationships of each element is still ambiguous. Herein, we have successfully synthesized Au nanoparticles decorated Cux+-doped ZnO porous nanosheets (Au/Cu-ZnO) with a larger specific surface area, distinct surface and electronic structure, and the prepared sensors exhibit excellent gas sensing performance for ethanol. Notably, Au/Cu-ZnO sensors display superior sensing response (R a /R g =95.45) to 50 ppm ethanol at 160 °C, which is 2.91, 2.45 and 9.31 folds than Au-ZnO, Cu-ZnO and ZnO, the sensors also exhibit low limit of detection (172.5 ppb), fast recovery (34 s) and high selectivity. Several characterizations and DFT calculations reveal that the downshifts of the d -band center can be observed after Cu immobilized, which greatly optimize the adsorption and desorption behavior. Additionally, the introduction of Cu facilitates the formation of oxygen vacancy, endowing the materials with more amount of high mobility O- (ad) species, which contributes to the enhanced sensing performance. This work provides new insights for the designation of high-performance sensing materials and deep investigation of sensing mechanisms. • The Au/Cu-ZnO has been successfully prepared by a simple method. • The sensors show superior gas sensing performance to ethanol. • The introduction of Cu facilitates the formation of oxygen vacancy and the downshifts of d -band center. • Bimetal co-catalysis effect improve sensing performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • Dual functionalized Ni substitution in shuttle-like In 2 O 3 nanoparticles (NPs) has been synthesized. • The 2 wt% Ni-doped In 2 O 3 NPs exhibit high sensitivity (R a /R g = 2569.42 towards 50 ppm NH 3 at 140 °C), achieving 34 folds improvement compared with pristine In 2 O 3 NPs. • Ni substitution in rh-In 2 O 3 NPs can effectively modulate the electronic structure and surface acidity of material and further improve the adsorption of NH 3. • The substitution of Ni in rh-In 2 O 3 phase and surface O−(ad) species neighboring the substitution sites are recognized as the active sites. Hetero-atom doping is an effective way to improve the sensing performance of metal oxide semiconductor gas sensors. However, the synergistic effects generated from hetero-atom substitution in In 2 O 3 lattice and the relationship between the fine surface structure and sensing performance is still ambiguous. Here, Ni substitution in shuttle-like In 2 O 3 nanoparticles have been successfully synthesized, and the materials are fabricated as gas sensor to detect ammonia, which is a toxic molecule that is harmful for human healthy. We find the 2 wt% Ni-doped In 2 O 3 NPs exhibit high sensitivity (R a /R g = 2569.42 towards 50 ppm NH 3 at 140 °C), achieving 34 folds improvement compared with pristine In 2 O 3 NPs. The sensor also shows good long-term stability, high selectivity and fast response/recovery (23/10 s). Detail structural analysis illustrate the substitution of Ni in rh-In 2 O 3 phase and surface O−(ad) species neighboring the substitution sites are recognized as the active sites, and the reactive oxygen species and surface Bronster acidity can be dramatically enhanced after Ni modification, which contribute to the improvement of sensing performance. Our work illustrate the synergistic effects of hetero-atom doping on the sensing performance and pave the way for design of high performance sensing materials. [ABSTRACT FROM AUTHOR]