## 5 Conclusions  
In the present work, a 0.5 mol % Cu-doped TiO\({}_{2}\) visible light active semiconductor material has been synthesized through a sol-gel approach. The as-synthesized materials have been thoroughly characterized with the help of XRD, XPS, Raman, UV-DRS and DFT analyses. The introduction of a small mole percent of Cu inside the TiO\({}_{2}\) crystal lattice has led to increased thermal stability and antimicrobial efficiency. The anatase phase of TiO\({}_{2}\) is retained well up to 650 \({}^{\circ}\)C by Cu doping. Almost all micro-organisms tested (_E. coli_ and _S. aureus_) are inactivated by Cu-TiO\({}_{2}\) within 30 min of visible light irradiation. The high antimicrobial efficiency of Cu-TiO\({}_{2}\) is attributed to the synergistic effect of p-n junction (between TiO\({}_{2}\) anatase and rutile), heterojunctions formed (between TiO\({}_{2}\) and Cu\({}_{2}\)O) and of copper ions. The results have also compared with pure TiO\({}_{2}\) anatase and rutile. The as-synthesized high temperature stable smart materials could be used to develop antimicrobial coatings or can be incorporated in paints or building wares (ceramics, tiles, etc.) as a potential antibacterial agent.  
The following are available online at [[http://www.mdpi.com/2076-3417/8/11/2067/s1](http://www.mdpi.com/2076-3417/8/11/2067/s1)]([http://www.mdpi.com/2076-3417/8/11/2067/s1](http://www.mdpi.com/2076-3417/8/11/2067/s1)), Figure S1: XRD profiles of undoped TiO\({}_{2}\) at different temperatures, Table S1: Summarise glance of literature of Cu-TiO\({}_{2}\) for Antimicrobial disinfection.  
Conceptualization, S.C.P.; methodology design, C.B.; experimental, investigation, data creation, data analysis and draft preparation S.M. and P.G.; data creation and editing, S.R., M.N., S.J.H.; editing, V.K., C.B. and S.C.P.; supervision, J.B. and S.C.P.  
Figure 12: Schematic illustration of photocatalytic disinfection shown by possible two mechanisms (**a**) p-n junction by Cu\({}_{2}\)O and TiO\({}_{2}\) (**b**) Type-2 heterostructure by anatase and rutile titania.  
**Funding:** The research was funded by European Union's INTERREG VA Programme, managed by the Special EU Programmes Body (SEUPB), with match funding provided by the Department for the Economy and Department of Jobs, Enterprise and Innovation in Dublin, Ireland, grand number IVA5033. P.G & C.B would like to acknowledge the Institute of Technology Sligo President's Bursary for providing financial support, grant number PPRES052 and PPRES032. S.R. and M.N. acknowledge support from Science Foundation Ireland through the US-Ireland R&D Partnershop program, Grant number SFI/US/14/e2915 and the ERA.Net for Materials Research and Innovation (M-ERA.Net 2), Horizon 2020 grant agreement number 685451, SFI Grant Number SFI/16/M-ERA/3418 (RATOCAT).  
**Acknowledgments:** [PERSON], [PERSON], C.B. and S.C.P. would like to acknowledge access to Raman Spectroscopy at Centre for Research in Engineering Surface Technology (CREST), FOCAS Institute, Dublin Institute of Technology, Kevin Street, Dublin, Ireland. [PERSON]. & P.G. would like to acknowledge [PERSON] for helping in bacterial culture. [PERSON] and M.N. acknowledge access to SFI funded computing resources at Tyndall Institute and the SFI/HEA funded Irish Centre for High End Computing. We are grateful for support from the COST Action CM1104 \"Reducible Metal Oxides, Structure and Function\".  
**Conflicts of Interest:** The authors declare no conflict of interest.