**Acknowledgements**

W cm-2). The improved performance of the composite is attributed to the hybrid synergy effect of silica hygroscopic property and N-doped dopamine-induced carbon layer. Additionally, the N-doped carbon obtained after the carbonization step could make the composite more conductive with the enhancement of charge transfer at interfaces. As a result, these advantages of the Pt and dopamine-induced carbon@silica composite could contribute to enhance performance under low humidity conditions compared to the commercial Pt/C catalyst.

160 Advanced Catalytic Materials - Photocatalysis and Other Current Trends

**Figure 18.** I-V polarization (left axis) and power density (right axis) curve for PEMFC single cell (H2/O2) with Pt and Ndoped carbon@silica nanocomposites (red triangle) and commercial Pt/carbon (black circle) used as an anode catalyst

We have presented various techniques to obtain novel catalysts that successfully enhance the efficiency and productivity of PET glycolysis for monomer recycling as well as the performance of polymer electrolyte membrane fuel cells. The catalysts can be considered a practical solution that addresses various issues in these processes, such as catalyst separability, reusability, and performance in limited operating conditions. The use of ultrasound-assisted synthesis provided an efficient alternative synthesis approach to obtain metal-oxide composites of silica and graphene oxide under mild conditions. The use of these catalyst composites offers the potential of industrial-scale use given their high activity in addition to thermal and chemical stability. Another practical and effective approach is the use of a magnetically recoverable catalyst, γ-Fe2O3. The superparamagnetic nanocatalyst, offering comparable performance and stability as the other solid catalysts, has further advantages of efficient separation and relatively simplicity of synthesis approach. For fuel cell development, we developed a nontoxic and easy chemical method to fabricate Pt and dopamine-induced carbon@silica compo‐ site without complex apparatus. The silica nanoparticles as support material acted as a selfhumidifying material, while the dopamine coating played the role of a self-reducing agent and adhesive layer for anchoring the Pt nanoparticles. Additionally, the N-doped carbon from

under relative humidity at 0%.

**4. Conclusion**

This work was supported by the R&D Center for Valuable Recycling (Global-Top Environ‐ mental Technology Development Program) funded by the Ministry of Environment (Project No.: GT-11-C-01-250-0) and by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (No. 2014R1A5A1009799).
