**4. Conclusions**

A novel and practical method for the fabrication of a CuII/I@CMC-PANI film dip catalyst was developed via spray-assisted interfacial polymerization. In the preparation process, carboxymethylcellulose and copper sulfate served as the soft template and initiator, respectively, for the polymerization of aniline monomers, and the spraying method provided a unique interfacial layer to facilitate polymerization. This as-prepared film catalyst was well characterized by ICP, FT-IR, XPS, XRD, SEM, EDS, and TGA techniques. These characterized results proved that aniline had successfully polymerized to PANI onto the CMC molecular chain, and that Cu(II)/Cu(I) oxides, at the nano scale, were homogeneously loaded into the CMC-PANI film at the same time. The obverse and back side of the resultant film had different morphologies, due to their different PANI contents. In terms of application, the as-synthesized CuII/I@CMC-PANI film dip catalyst possessed good thermal stability up to 200 ◦C, and could be efficiently applied in the A<sup>3</sup> coupling reaction, due to its excellent recyclability and tolerance of a broad scope of substrates.

**Supplementary Materials:** The following supporting information can be downloaded at: https:// www.mdpi.com/article/10.3390/nano12101641/s1, The spectra data, 1H and 13C NMR for all products (**<sup>a</sup>**–**q**), FT-IR 19F NMR and HRMS for new product (**i**). References [48–61] are cited in the Supplementary Materials.

**Author Contributions:** Investigation, data curation, formal analysis, methodology, visualization, writing—original draft, Z.X.; investigation, methodology, L.X., X.F., D.L. and L.M.; conceptualization, supervision, methodology, resources, funding acquisition, project administration, writing— review and editing, G.N. and Y.L. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was financially supported by The Natural Science Foundation of Guangdong Province (No. 2020A1515010399), Guangxi Innovation Driven Development Major Project (No. Guike AA20302013), Nanning Scientific Research and Technology Development Plan Project (No. RC20200001), "Yongjiang Plan" Project of Leading Talents of Innovation and Entrepreneurship in Nanning City (No. 2020024), and Yulin City Science and Technology Transformation Project (No. 19040003).

**Data Availability Statement:** Data are within the article and Supplementary Materials.

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