Perfect is Not Always Better—Oxygen Vacancy-Rich Metal-Oxides and Their Use for the Additive Manufacturing of Sunlight-Activated Photocatalytic Cells and Other Complex Device Architectures

In recent years, our team worked intensely on exploring new sol-gel chemistry for metal-oxides and exploiting electro-deposition techniques to form complex film architectures. A very clever idea was implemented, using chelation to produce oxygen vacancy-rich amorphous metal-oxyde particulates [1]. In turn, these oxygen vacancies dramatically increase the absorption of light, and even allow conversion to fully-crystallized TiO2 (amorphous and rutile) using low-doses of visible light irradiation in ambient environment [1,2]. In turn, we will present several exciting new all-printed optoelectronic devices that were recently manufactured using these new materials including printed temperature & pressure sensors, photodetectors and solar cells [3].<br/>This last year, we realized new and exciting nanostructured metal-oxide frameworks to achieve efficient photocatalytic degradation using only sunlight irradiation [4]. This exciting new technology relies on a metal-oxide sponge-like films produced from a solution-based formulation and coated with a thin Pt coating for metal enhancement Until now, photocatalytic cells used to degrade organic contaminants in water suffered two great problems. (1) UV lamps are required for optimal photocatalytic degradation. (2) They release particulates during the photocatalytic reaction, requiring subsequent filtering to avoid indirect contamination. In these last months, superior photocatalytic efficiency was achieved using only sunlight exposure (from a solar simulator at AM-1.5G), thus illuminating the need for UV lamps. Compared to state-of-the-art photocatalytic materials, dramatically-smaller volumes (µg/L) of material are released after five degradation cycles using the same cell [4]. Building on this exciting discovery, similar results were just achieved recently using our oxygen vacancy-rich metal-oxide formulations [1,2]. While their photocatalytic efficiency is slightly less, it relies on a much greener sol gel-based chemical synthesis route [1].<br/>Finally, we will also describe how we are currently transitioning these complex solution-based oxygen vacancy-rich metal-oxide photocatalytic materials and structures to manufacturing-ready equipments including high-speed photonic lamps for curing on low-temperature substrates and digital inkjet printing capabilities [5,6]. As such, we believe these exciting new photocatalytic materials and devices will soon transition to large-scale manufacturing to contribute to the fight against air & water pollution.<br/>[1] J. Benavides <i>et al</i>., ACS Applied Energy Materials <b>1</b>, 3607 (2018)<br/>[2] L. F. Gerlein<i> et al</i>., Advanced Engineering Materials <b>22</b>, 1901014 (2020)<br/>[3] D. Banerjee <i>et al</i>., npj - Scientific Reports <b>9</b>, 17994 (2019)<br/>[4] P. Fourmont, R. Nechache and S. G. Cloutier. ACS Applied Nano Materials (Accepted - Published online: 10.1021/acsanm.1c02762)<br/>[5] B. N. Altay <i>et al</i>., npj - Scientific Reports <b>11</b>, 3393 (2021)<br/>[6] C. Trudeau <i>et al</i>., npj - Flexible Electronics <b>4</b>, 2136 (2020)