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Acetone, one of the most used solvents in industry and the laboratory, can anesthetize the central nervous system of humans and cause damage to the kidneys, pancreas, and liver. For the purpose of monitoring the leakage and concentration of acetone, α-/γ-Fe 2 O 3 /TiO 2 -X (α-/γ-Fe 2 O 3 -X) materials were successfully manufactured by in-situ solvothermal and calcination processes. Here, MIL-100-derived porous α-/γ-Fe 2 O 3 and TiO 2 nanoparticles are uniformly grown on the self-sacrificial template of exfoliated Ti 3 C 2 T x nanosheets (ex-Ti 3 C 2 T x) that simultaneously serve as the Ti source. The heterostructure between TiO 2 and Fe 2 O 3 therein is conducive to carrier transfer and sharp resistance change. And bulk resistance-controlled γ-Fe 2 O 3 is able to raise the response to gas. Besides, the porous structure of α-/γ-Fe 2 O 3 -X could create plenty of oxygen vacancies and surface functional groups, which facilitate diffusion and contact interaction between acetone and active sites. Accordingly, the α-/γ-Fe 2 O 3 -X endow exceptional response (R = 105.5) towards 100 ppm acetone at 240 ℃, fast response/recovery time, outstanding selectivity and stability. To further substantiate this promotion mechanism, density functional theory (DFT) calculations were carried out for investigating the adsorption behavior of α-/γ-Fe 2 O 3 -X for acetone. • MIL-100 derived porous bi-phase α-/γ-Fe 2 O 3 nanoparticles are first proposed. • α-/γ-Fe 2 O 3 -X heterostructures promote carrier migration and resistance modulation. • γ-Fe 2 O 3 further improves the sensitivity through its internal structural changes. • The porosity, defects and functional groups of α-/γ-Fe 2 O 3 -X offer reactive sites. • The DFT calculations are investigated to elucidate the gas sensing mechanism. [ABSTRACT FROM AUTHOR]

Acetone is used in a variety of fields for being highly volatile chemicals that may have detrimental effects on both industrial security and human health. With a view to testing the leak and concentration of acetone, we have successfully developed TiO 2 /Fe 2 O 3 -X (TF-X) sensors via a carboxyl group-shared coordination route. Here, Ti 3 C 2 T x MXene and Fe salt provide chelation sites enabling coordination with carboxyl groups to fabricate two kinds of MOFs (MIL-125(Ti)/MIL-53(Fe)) followed by calcination. The tightly coupled heterogeneous interface between TiO 2 and Fe 2 O 3 promotes carrier transfer and elicits sharp resistance variation thereby raising the sensitivity towards acetone. Meantime, the porous TF-X heterostructures generate numerous oxygen vacancies and surface functional groups to be conducive to the gas flow and surface reaction. Accordingly, the optimal TF-400 heterostructure endows the extraordinary sensitivity (R = 446.8) to 100 ppm acetone at 268 ℃, much higher than that of the pristine TiO 2 and Fe 2 O 3. Rapid response (15 s) and recovery (7 s) time are implemented, as well as remarkable selectivity and stability. Moreover, the enhanced mechanism of TF-400 heterostructure is presented and studied. It is anticipated to open up a new avenue for the design and synthesis of high-sensitivity acetone sensors. [Display omitted] • An artful strategy of MXene and Fe salts as bimetallic sources is first proposed. • The TF-X heterostructures make for carrier migration and resistance modulation. • The surface defects and functional groups raise the sensitivity of porous TF-X. • The reaction mechanism is proposed and investigated. [ABSTRACT FROM AUTHOR]

[Display omitted] • A strategy of MXene as a metal source for the growth of MFT T -X is first proposed. • The MIL-125(Ti) and Fe x Ti y O z nanoparticles are grown on the Ti 3 C 2 T x template. • The sensitive sensor due to narrower bandgap, surface defects and porous structure. • The reaction mechanism is explored and investigated. Acetone, with diverse applications in multiple areas, may pose a risk to industrial safety and human health. For the purpose of detecting the leakage and concentration of acetone, we have successfully prepared [MIL-125(Ti)/Fe x Ti y O z ] T -X (MFT T -X) gas-sensitive materials by in-situ solvothermal and calcination methods. Herein, the porous MIL-125(Ti) and Fe x Ti y O z nanoparticles with intimate interfaces are grown on the template of exfoliated Ti 3 C 2 T x nanosheets that simultaneously serve as the Ti source. The narrower bandgap, numerous surface defects, increased specific surface area, and mesoporous structure of MFT T -X composites are conducive to the diffusion and contact among acetone gas and active sites. The optimum MFT 450 -8 composite endows significantly enhanced sensitivity (R = 351.1) towards 100 ppm acetone at 222 °C, ultrafast response and recovery time (16 s / 5 s), good repeatability, and excellent selectivity. These results provide new insight into the design of high-performance sensing materials, modified with MXene derived MOFs, and analyzed the reaction mechanism of acetone that is relevant to MFT 450 -8 composite. [ABSTRACT FROM AUTHOR]

[Display omitted] • The porous bi-phase α-/γ-Fe 2 O 3 nanoparticles are derived from MIL-53(Fe) for the first time. • The assembling of porous bi-phase α-/γ-Fe 2 O 3 nanoparticles in exfoliated Ti 3 C 2 T x nanosheets generates high-performance α-/γ-FT-X acetone sensing material. • Improved sensitivity due to multiple heterojunction interfaces, surface defects, and porosities. • Novel sensing mechanism is proposed and investigated. Acetone is one of the volatile organic compounds (VOCs), which is found in precarious both human health and the environment. For efficient detection of acetone gas concentration and leakage, we have successfully synthesized stable α-/γ-Fe 2 O 3 /ex-Ti 3 C 2 T x -X gas sensing material via in-situ solvothermal and calcination method, in which MIL-53(Fe)-derived porous bi-phase α-/γ-Fe 2 O 3 nanoparticles uniformly growing on the surface and interlayers of exfoliated Ti 3 C 2 T x nanosheets (α-/γ-FT-X). The numerous heterojunction interfaces, surface defects, and porosities of α-/γ-FT-X composites can simultaneously facilitate the diffusion process and contact interaction between acetone molecules and active sites. Strikingly, the optimal α-/γ-FT-4 composite possesses the superior sensitivity (R = 215.2) towards 100 ppm acetone at 255 ℃, which is nearly 8 times higher than that of α-/γ-Fe 2 O 3 (R = 26.2) and much higher than exfoliated Ti 3 C 2 T x nanosheets (R = 3.8), respectively. Moreover, fast response (13 s) and recovery (8 s) properties are achieved, as well as outstanding repeatability and remarkable selectivity. An enhancement mechanism for α-/γ-FT-4 composite is proposed and investigated. It is expected for us to open an effective avenue for fabricating efficient acetone sensing materials. [ABSTRACT FROM AUTHOR]