## 1 Introduction  
The global energy shortage and environmental pollution due to heavy reliance on limited fossil fuels are key challenges facing mankind. To fulfill -82% of our total energy demand, 12 million tons of oil, 22 million tons of coal, and 10 m\({}^{3}\) of natural gas are consumed every day [1, 2]. Unfortunately, when energy is extracted from these resources, a large volume of CO\({}_{2}\) is emitted. This causes environmental concerns, including global warming, ocean acidification, and the related macroscopic effects they induce [3]. In the past century, and in particular during the last two decades, the Earth's surface temperature has steadily increased. This has been univocally correlated with increasing anthropogenic CO\({}_{2}\) emissions, which recently surpassed 400 ppm concentration in the atmosphere, which was considered a threshold of non-return. Finding an alternative energy resource with advancements in technological development could pave the way toward solving this challenge with a sustainable supply of fuels and chemicals. The use of photovoltaic panels [4] to exploit solar energy is one of the options, but intermittency issues and the requirement of a large area are key concerns. As a result, research on photocatalysis as a way to store solar energy in chemical form has gained momentum [5] to exploit solar light storage in chemical form for use when sunlight is not available. Its major applications are the production of renewable hydrogen via the photoreforming of organic molecules and various oxygenated products produced through CO\({}_{2}\) photoreduction to solar fuel using semiconductor-based heterogeneous photocatalysts. Since this process utilizes CO\({}_{2}\) as feedstock and turns it into advanced fuel or renewable chemical reagents, such as formic acid, formaldehyde, and methanol (Scheme S1, Supplementary Information File), under mild conditions (<100 \({}^{\circ}\)C) using water as a solvent [5; 6; 7; 8; 9], improved environmental sustainability is expected [3]. Water photosplitting is another very interesting process for obtaining solar fuels (i.e., H\({}_{2}\)), though very low hydrogen productivity has been reported. This is due to the faster recombination of electrons and holes after their production via the photoexcitation of a semiconductor photocatalyst. The charge's relaxation is typically faster than the reactions to be promoted [10; 11; 12; 13; 14]. Different organic compounds have been proposed as hole scavengers to improve the rate of reaction, and carbohydrates represent an interesting option that allow for the exploitation of waste aqueous solutions (e.g., from the paper, milk, and food industries). Most of the available literature dedicated to photosynthetic applications has relied on titania based materials in cases where it is added with metal co-catalysts or coupled in a Z-scheme with a small band gap semiconductor to improve visible light harvesting. Evonik P25 TiO\({}_{2}\) powder is often used for photocatalytic applications as it is a commercial, widely available, and reproducible material. P25 is prepared through the hydrolysis of an aerosol of a titania precursor (TiCl\({}_{4}\)) [15]. It structurally comprises a mixture of anatase and rutile (ca. 3:1). The higher photocatalytic activity of P25 compared to pure anatase and rutile titania has been attributed to the passage of electrons from one phase to the other, thus improving charge separation and leading to the stabilization of photogenerated charges for a longer time than in pure phases [11; 16; 17]. As a drawback, the use of nanosized photocatalysts in the form of powder is fine for testing the intrinsic activity of the catalyst in batch small scale thanks to its high surface area and maximum exposure to the light, but it is not at all feasible for large scale and continuous processes. Indeed, it is very challenging to recover or recycle a photocatalyst after the end of the process, which in turn results in increased costs and longer processing times [18].