**4. Conclusions**

In this study, a nano-cellulose/MOF-derived carbon-doped CuO/Fe3O4 composite catalyst was successfully fabricated through pyrolysis/thermolysis of the HKUST-1/Fe3O4/CMF composite. The resultant carbon-doped CuO/Fe3O4 composite catalyst took advantage of the original porous morphology of HKUST-1; consequently, the carbon-doped CuO/Fe3O4 composite catalyst exhibited high catalytic activity for the reduction of 4-NP and organic dyes (MB and MO). In addition, the carbon-doped CuO/Fe3O4 composite catalyst showed good reusability/recyclability after five cycles. Notably, this strategy can be extended to the preparation of other functional MOF-based derivatives.

**Author Contributions:** Conceptualization, H.L. and L.Z.; Methodology, H.L.; Software, H.L. and N.A.; Validation, N.A. and J.M.; Formal Analysis, H.L. and L.Z.; Investigation, H.L.; Resources, X.Z. and Y.N.; Data Curation, J.M.; Writing-Original Draft Preparation, H.L.; Writing-Review & Editing, X.Z. and Y.N.; Visualization, L.Z. and J.M.; Supervision, Y.N.; Project Administration, X.Z. and Y.N.; Funding Acquisition, X.Z. and Y.N.

**Funding:** This research was funded by the National Natural Science Foundation of China (31570576), the financial support from the Natural Science Foundation of Jiangsu Provincial University (16KJA220005), the Canada Research Chairs program of the Government of Canada, the Postgraduate Research and Practice Innovation Program of Jiangsu Province (KYCX17\_0835), the Doctorate Fellowship Foundation of Nanjing Forestry University, and the Priority Academic Program Development (PAPD) of Jiangsu Higher Education Institutions. The APC was funded by the Natural Science Foundation of Jiangsu Provincial University (16KJA220005).

**Acknowledgments:** The authors acknowledge Mike Johnson (Department of Chemistry and Institute for Research in Materials, Dalhousie University, Halifax, NS, Canada) for the acquisition and interpretation of the PPMS data.

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