Pt-doped TiO2 nanotubes as photocatalysts and electrocatalysts for enhanced photocatalytic H2 generation, electrochemical sensing, and supercapacitor applications

Abstract

Hydrogen production plays a major role in both the stationary and transportation energy sectors. Electrochemical sensing is an additional sensitive electrochemical application for the detection of trace analytes. Semiconductor-based catalysts can be used for both of these applications. While doping these semiconductors, it improves the pure semiconductor's electrical properties. TiO2 nanotubes (NTbs) and Pt-doped TiO2 NTbs were successfully synthesized by the hydrothermal method at various doping concentrations. They were subjected to different methodical characterization tools such as XRD, FT-IR, UV-DRS, SEM, and TEM. Out of various doping concentrations of Pt, 1.6% Pt-doped TiO2 NTbs shows superior H2 generation through photocatalytic water splitting reactions, which is attributed to the high electrical conductivity and stable electrical properties of it with a low impedance of 79 Ohms. The amount of hydrogen gas produced from 1.6% Pt-doped TiO2 was found to be 19.22 mmolh−1g−1, which is due to the reduced band gap of the material from the incorporation of Pt into pure TiO2. Prepared NTbs were examined for their electrochemical activity towards the detection of nitrite at very low concentrations. The enhanced electrochemical activity of 1.6% Pt-doped TiO2 NTbs is effective in detecting nitrite with a detection limit of 14.7 nM. A supercapacitor device has been constructed using 1.6% Pt-doped TiO2. The constructed device produced stable cyclic voltammograms up to the maximum scan rate of 10,000 mVs−1 with a potential window of 2 V. The maximum specific capacitance and Energy density (Ed) of a 1.6% Pt-doped TiO2-based supercapacitor were determined to be 750.01 F/g and 78.8 Wh/Kg, respectively. These results demonstrate that it is an excellent material for energy storage applications.