From lab to pilot scale: Assessing the behavior and effect of indigenous hole scavenger for photocatalytic hydrogen generation in bi-metallic system Au-Pt/TiO 2

In the present investigation, two types of titania supported bi-metallic nanoparticles, Au-Pt/TiO2 Rec and Au-Pt/TiO2 In-situ, were synthesized and studied for photocatalytic hydrogen generation under UV and solar radiation. Delayed electron-hole recombination due to indigenous chloride ion released from Au & Pt precursor salts was identified as a key parameter influencing the unprecedented hydrogen evolution rate of Au-Pt/TiO2 In-situ. The highest hydrogen evolution rate (HER) achieved under UV-visible light was 17 mmol h−1, not reported so far. Stability tests conducted for over 100 h confirmed long-term stability and hydrogen generation. The catalysts were characterized by various techniques to correlate structure with performance. Au-Pt nanoparticles in nanocomposite form (2–5 nm) were observed, with XPS shifts confirming Au and Pt existence. The most unique feature lies in testing of the photocatalyst at a designed 30 L pilot scale, yielding 177 mmol h−1 hydrogen. Our results indicate that the HER activity is currently at the higher end of the reported efficiencies.