**6. Conclusions**

The application of various MOFs materials was reviewed with a focus on toxic sensor, reduction catalyst, hydrogen storage, and filter, which act as successful functional materials. We reviewed all of the materials while using MOFs that exhibited good performance and various application. The application of MOF material for toxic sensor, such as NO2, SO2, and ammonia gas, showed high performance via MFM-300 (Al), Co based MOFs (Co2Cl2BTDD and Co2Cl2BBTA), and MFM-300 (In). Our previous catalyst e.g., PdAg@UiO-66-L for the detection and reduction of 4-nitrophenol also showed good catalytic activity. Moreover, a new Cd-MOF as a fluorescent detect exhibited high sensitivity and selectivity in CRO. Various MOFs for hydrogen adsorption, such as MOF-177, SNU-6, and MOF-74 composited by Co/Ni mixed-material, exhibited good performance while using physisorption analysis method. Filtration for particle matters and wastewater using organic fiber modified as MOF-based material showed good adsorption in polluted condition. In summary, MOFs can be expected one of the best candidate to solve environmental pollution and energy storage in the near future.

**Author Contributions:** K.H.P. provided academic direction and Discussion of the results and revising the full manuscript. S.J. collected materials and wrote the introduction, basic of stable MOFs, and conclusion part. S.S. and J.H.L. contributed to the materials and methods and results and discussion equally. H.S.K., B.T.P., K.-T.H., and S.P. participated in discussion of the results. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2017R1A4A1015533, 2017R1D1A1B03036303 and 2018R1D1A1B07045663). This research was partially supported by VietNam National University Ho Chi Minh City (NCM2019-50-01).

**Acknowledgments:** This research was supported by PNU-RENovation (2018–2019).

**Conflicts of Interest:** The authors declare no conflict of interest.
