Surface functionalization-driven TiO2 incorporation by atomic layer deposition on nanoporous carbon: Interfacial effects on charge storage

This work investigates the effect of oxygen surface functionalization on TiO 2 incorporation and the electrochemical performance of nanoporous carbon electrodes prepared by atomic layer deposition (ALD). Pristine commercial activated carbon and its functionalized derivatives with hydroxyl and carboxyl were used to evaluate how surface chemistry influences the Ti precursor interaction and the resulting carbon-TiO 2 interface after 200 ALD cycles. Physicochemical characterization (XRD, Raman, and XPS) reveals that the oxygen-containing functional groups significantly modify the carbon structure and promote stronger interactions with the TiO 2 phase. Although the deposited TiO 2 is predominantly amorphous due to the low deposition temperature (120 °C), differences in Ti incorporation are observed depending on the surface functionality. In particular, hydroxyl-functionalized carbon exhibits a higher Ti content, indicating more favorable conditions for oxide incorporation and interfacial interaction. Electrochemical analysis demonstrates that both surface functionalization and TiO 2 incorporation enhance capacitive performance, with the carbon-TiO 2 electrode functionalized with OH groups exhibiting the highest specific capacitance in both acidic and alkaline electrolytes. This improvement is attributed to the synergistic contribution of electric double-layer capacitance and pseudocapacitance, as well as improved charge transfer at the carbon-TiO 2 interface. These findings provide new insights into the design of ALD-grown carbon/metal oxide for electrochemical energy storage.