Interfacial engineering of conformal titanium oxide nanofilms on porous carbon supercapacitor electrodes via atomic layer deposition

Abstract

We report the development of an atomic layer deposition (ALD) process for depositing titanium dioxide (TiO2) nanofilms onto porous activated carbon (AC) electrodes to enhance the electrochemical performance of supercapacitors. This study investigates previously unexplored aspects of the ALD process, including the influence of precursor pulse duration and film thickness on the deposition behavior within complex porous AC structures. The deposited TiO2 nanofilms were amorphous and exhibited excellent uniformity and conformality across the AC surface. Electrochemical measurements revealed a combination of surface redox and intercalation-type pseudocapacitance, with surface redox reactions identified as the dominant energy storage mechanism. An optimal balance between accessible surface area and film thickness was achieved at 60 ALD cycles, corresponding to a TiO2 film thickness of approximately 2.3 nm. Under these conditions, the specific capacitance of TiO2-coated supercapacitors exceeded that of bare AC electrodes, owing to the additional pseudocapacitance contributed by the TiO2 layer. These findings demonstrate an effective strategy for utilizing ALD to engineer advanced electrode materials for high-performance supercapacitors.