Pt decorated CoFe <sub>2</sub>O <sub>4</sub>/Co <sub>3</sub>O <sub>4</sub> nanosheets derived from 2D Fe–Co MOF for enhanced HCHO detection
Yuli Zhao, Mingyuan Wang, Siwei Liu, Xiangzhao Zhang, Guiwu Liu, Guanjun Qiao
Abstract
Highly sensitive and selective detection of volatile organic compounds (VOCs) is of great significance, and designing a suitable microstructure and constructing heterostructures are two main effective strategies for gas-sensing materials to achieve this goal. Herein, Pt nanoparticles decorated CoFe<sub>2</sub>O<sub>4</sub>/Co<sub>3</sub>O<sub>4</sub> nanosheets were prepared by solution method for highly accurate detection of formaldehyde (HCHO), where the CoFe<sub>2</sub>O<sub>4</sub>/Co<sub>3</sub>O<sub>4</sub> nanosheets were derived from two-dimensional Fe-Co metal-organic framework (MOF). The response (<em>R</em><sub>g</sub>/<em>R</em><sub>a</sub>) of ternary Pt<sub>2</sub>/CoFe<sub>2</sub>O<sub>4</sub>/Co<sub>3</sub>O<sub>4</sub> composite to 100 ppm HCHO at 280 °C can be calculated as 95.5, and it still exhibits a very high response to low concentration of HCHO (1.26 to 50 ppb HCHO gas) and an ultra-low limit of detection (LOD) of 6 ppb. The ternary composite also presents excellent reproducibility, selectivity and long-term stability. The first-principles calculations demonstrate that the Pt/CoFe<sub>2</sub>O<sub>4</sub>/Co<sub>3</sub>O<sub>4</sub> model presents the most stable structure and the strongest adsorption capacity for HCHO. The high sensitivity of Pt/CoFe<sub>2</sub>O<sub>4</sub>/Co<sub>3</sub>O<sub>4</sub> to HCHO can be mainly ascribed to the formation of multi-heterojunctions and the catalytic effect of Pt nanoparticles. This work provides a facile preparation of MOF-derived multi-heterojunction materials, and highlights superior gas-sensing performances to VOCs.