Interfacial engineering of FTO/TiO2 interface via Au nanoparticles for quantum dot sensitized solar cells and photoelectrochemical H2 generation applications

Doping of noble metals in TiO2 has been known to be an excellent way to enhance light absorption and reduce charge recombinations in sensitized photoanodes based devices. In the present work, a relatively diverse approach of Au inclusion at the FTO/TiO2 interface has been utilized seeking enhanced light absorption and minimal charge recombinations to further extent. Here, both the diameter and amount of Au NPs at the FTO/TiO2 interface has been varied for quantum dot sensitized solar cells (QDSSCs) and solar driven photoelectrochemical cell (PECs) for H2 generation. From the FESEM images, clustering of Au on the FTO substrate has been observed which result in dendritic like morphology. Further from the UV–Vis and PL spectra of FTO/Au/CdS@TiO2 based photoanode, it is observed that, Au inclusion enhances light absorption and reduces recombinations. Photoanode containing 100 μl of 20 nm Au NPs provides maximum light absorption and minimum number of recombinations. Same photoanode gives highest PCE of 2.26 % in QDSSCs and maximum H2 liberation of 146.3 μl.cm−2 per day in PECs at ambient light intensity (0.5 mW/cm2). The inclusion of Au is also found to enhance stability of the device due to its high thermal conductivity which withdraws extra heat produced at the FTO/TiO2 interface due to long term light exposure.