Carbon Nanodots for Photocatalytic Hydrogen Generation from Seawater

JANA, BIKASH; SCHARL, TOBIAS; REVA, YANA; ALEJANDRO CADRANEL; GULDI, DIRK

Conferencia; International Solar Fuels Conference; 2021

Climate change is a reality. The planet?s temperature rise correlates with an increase of anthropogenic CO2 emissions, mainly stemming from fossil fuel burning.[1] Therefore, it is imperative to explore renewable and clean, alternative energy sources. Among the many approaches, hydrogen evolution reaction (HER) photocatalysis stands out. It pursues the transformation of sunlight into dihydrogen, which can be later burned to extract energy, producing innocuous water. Current photocatalytic HER strategies usually involve the use of metal ion-based components, which seem inconvenient due to their toxicity, poor environmental friendliness, and also scarcity in the case of heavy metal ions.In this context, nanocarbons are a versatile alternative to integrate in photocatalytic HER-schemes. They are efficient and robust in terms of photon and charge management in terms of light absorption, energy transfer and charge separation.[2] Additionally, they have shown promising catalytic HER activity.[3] Thus, a photocatalytic HER scheme based on nanocarbons and different sacrificial electron donors will be presented. Post-synthetic modifications afforded increased amounts of evolving hydrogen. The full photocycle was monitored in real time using femtosecond-to-microsecond transient absorption spectroscopy, which, in combination with electrochemical and spectroelectrochemical studies, allowed to propose a reaction mechanism. A key feature of these photocatalytic systems is that the nanocarbons themselves combine both light absorption and catalysis functions in only one component. Importantly, these studies also shed light into the chemistry of non-metal-based catalytic sites.