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The tannic acid induced assembly strategy was used to synthesize the Ni-doped SnO 2 nanosheets. The fabricated TA-Ni/SnO 2 sensors exhibited superior sensing performance to HCHO at working temperature of 80 °C (R a /R g = 184.3) and excellent sensing selectivity. The experimental and DFT results illustrated that the highly dispersed Ni substitution sites in SnO 2 crystals can be regarded as the active sites, which not only facilitated the generation of surface active O 2 –(ad) species, but also modified the electronic structure of SnO 2 crystals, contributing to superior sensing performance of TA-Ni/SnO 2 to HCHO. [Display omitted] • Tannic acid (TA) induced surface functional strategy is applied to synthesize Ni-doped SnO 2 nanosheets. • Ni ions can be highly dispersed on the SnO 2 nanosheets via TA. • The obtained materials exhibit superior sensing performance to HCHO. • The synergistic effects between O 2 –(ad) species and modified electronic structure contribute to the excellent sensing performance. Surface functionalization is a promising strategy to modulate the electronic and surface properties of metal oxide semiconductors. Here, we report a tannic acid (TA) induced surface functional strategy to synthesize Ni-doped SnO 2 nanosheets. Benefiting from the abundant polyphenolic and catechol groups, the linkage of TA not only exhibit high affinity to various substrate, but also show powerful chelating ability to metal ions. Hence, Ni ions can be highly dispersed on the SnO 2 nanosheets via TA, TA linkage also can prevent the aggregation of Ni ions during pyrolysis, and Ni substitution in SnO 2 crystals can be obtained. As a proof-of-concept demonstration, the TA-Ni/SnO 2 sensor is fabricated to detect HCHO, and exhibit superior sensing performance at low working temperature of 80 °C (R a /R g = 184.3), excellent sensing selectivity and long-term stability. Detail experimental and theoretical calculation demonstrate the highly dispersed Ni substitution active sites facilitate the generation of surface O 2 –(ad) species, and the electronic structure also can be modulated to exhibit high affinity to HCHO, hence, the synergistic effects contribute to the enhanced sensing performance. Our work paves the way for versatile surface functionalization to synthesize advanced materials for application in catalysis and sensing field. [ABSTRACT FROM AUTHOR]

We have designed hollow Co 3 O 4 /ZnO nanocage by MOFs derived method for detection of H 2 S, which seriously threatens human health. The Co 3 O 4 /ZnO-1 sensor exhibit superior sensing response (R a /R g = 546.2) to 5 ppm H 2 S at 110 °C, which is 32 folds than ZnO sensors with low detection limit (9 ppb), fast recovery (35 s) and high selectivity. Both theoretical and experimental results illustrate the enhanced sensing performance can be attributed to the Co sites induced synergistic effect. [Display omitted] • The hollow Co 3 O 4 /ZnO nanocages have been successfully synthesized. • The state of Co sites in Co 3 O 4 /ZnO can be finely tuned. • The sensor exhibits high response and selectivity at low temperature. • Co sites induced synergistic effect improve sensing performance. Metal organic frameworks (MOFs) derived Co 3 O 4 /ZnO heterostructure has been widely investigated to achieve the high sensing performance. However, the synergistic effects generated from the Co sites and the relationship between the surface structure and sensing performance is still ambiguous. Herein, the hollow Co 3 O 4 /ZnO nanocage heterojunctions have been successfully synthesized, and the state of Co sites can be modulated by finely tuning the coordination environment of Co species. Notably, the Co 3 O 4 /ZnO-1 materials exhibit superior sensing response (R a /R g = 546.2, 32 folds than ZnO sensors) to 5 ppm H 2 S at 110 °C, with low detection limit (9 ppb), fast recovery (35 s) and high selectivity. Detail structural analysis illustrates O 2 can be easily activated around the Co 3 O 4 /ZnO hetero-interface, and the formation of O− species with high mobility improves the surface reaction rate. Additionally, the catalytic reaction between highly dispersed Co species and H 2 S also facilitates the formation of CoS, which can synergistically enlarge the sensing response of sensors. Our work illustrates the state of Co species can greatly affect the sensing performance and pave the way for design of high performance sensing materials. [ABSTRACT FROM AUTHOR]