In response to the dramatic worldwide energy demand that we are currently suffering, artificial photo-synthesis (AP) has emerged as a sustainable alternative to the use of fossil fuels. AP systems are able to efficiently capture and convert solar energy and then store it in the form of chemical bonds. Therefore, solar energy induces the water splitting to produce hydrogen, and/or to transform carbon dioxide and water into a renewable source of energy rich carbon containing products. For this purpose, TiO₂ based photocatalysts are widely used owing to its availability at low cost. Unfortunately, TiO₂ is active only under UV light (4% of solar energy), while visible light contributes 43%, resulting in a low AP pathways efficiency. To carry out this process more efficiently, we are witnessing the renaissance of organic polymers (OP) and their participation in hybrid systems with inorganic semiconductors (ISs) in last years. The main advantage of OPs versus ISs ones is their tunable pore size, low density, structural periodicity and on demand chemical functionalization, that allows an excellent optoelectronic and surface catalytic properties [1]. Indeed, OPs and hybrids composites containing OPs have been widely applied in areas such as gas stor-age and separation, heterogeneous catalysis, energy storage and optoelectronic devices.

When designing a hybrid photocatalyst, an important aspect to consider is the type of charge transfer mechanism between both semiconductors, being the rate-determining step of the oxidation-reduction photocatalytic processes. At the same time, slightly molecular structure differences of OPs can lead to the increase of the hybrid transient absorption lifetimes during the charge transfer pathway and so, increasing the photocatalytic efficiency of the AP processes in terms of hydrogen production, CO₂ photoreduction or nitrogen fixation to ammonia (Figure 1). Herein, we demonstrate the usefulness of the photophysical techniques by means Steady-state and Time-Resolved Photoluminescence and well as Transient Absorption Spectroscopy (TAS) from the fs-to-s timescale to establish the mechanism governing the photocatalytic efficiency in hybrids photocatalysts under UV-visible light. The unique interfacial interaction between OP and IS results in longer carriers’ lifetimes of hundreds of ns, also taking into account parameters such as the dynamic quenching efficiency. These findings demonstrate a higher driving force for the electron transfer, which directly lead to an enhanced performance of the hybrids based on OPs and ISs compared to the bare materials [2,3]. These results establish the key between performance-structure relationships and highlight the pivotal role of highly tunable OPs and their respective hybrids with ISs for solar fuels production, as well as for a multitude of light-mediated energy applications.