Harnessing solar energy: Black TiO2 nanoparticles for superior photothermal and power generation

Abstract

This research focuses on synthesizing reduced Titanium Oxide, a promising photothermal material for energy harvesting applications. Reduced Titanium Oxide, which is otherwise known as Black TiO₂, is synthesized using a chemical reduction method where Sodium Borohydride acts as the reducing agent. The study introduces a ground breaking approach of developing a textile-based photothermal layer strategically integrated between Photovoltaic panel and Thermoelectric Generators. The novel photothermal layer is introduced to absorb wide range of solar spectrum, thereby improving the overall efficiency of the combined PV-TEG. Black TiO₂ coated on cellulose fabric through screen-printing technique acts as photothermal layer. By integrating this photothermal layer, the voltage output of the device was significantly enhanced to 3.9 V for TiO₂ and 4.6 V for Black TiO₂ as photothermal layers respectively, compared to 2.3 V for the standalone PV. The structural study reveals a shift towards higher angle indicating the oxygen vacancy in Black TiO₂. UV characterization of the photothermal material showed a band gap reduction from 2.5 eV for TiO₂ paste on cellulose fabric to 1.4 eV for Black TiO₂ paste and exhibit bathochromic effect. Thermal conductivity tests revealed values of 0.08 W/mK for TiO₂ nanoparticles and 0.1 W/mK for the Black TiO₂. Thermal imaging indicated a 2.8 °C temperature gradient in the S1PV-TEG system along with the photothermal layer. These findings demonstrate a significant advancement in solar energy utilization, promoting sustainable power generation.