Carbon Dots in Solar-to-Hydrogen Conversion

Abstract

Carbon dots (CDs) have found increasing application in solar-to-hydrogen conversion due to their low cost, low toxicity, and exceptional optoelectronic properties. Structure–property correlations in different CD systems have been developed, providing clear guidance for future investigations. CDs with desired physicochemical properties can be fabricated though structure manipulation. CDs have shown significant promise as photosensitizers, electron acceptors, electron donors, hole extractors, and cocatalysts in solar hydrogen production through water-splitting. Solar hydrogen production from catalytic water splitting is one of the many options available to help generate clean power and alleviate the threatening environmental concerns stemming from the use of fossil fuels. During the past decade, carbon dots (CDs) have shown great potential in their application for solar-driven hydrogen production owing to their exceptional photophysical and electrical properties derived from their sp2/sp3 hybridized core structure and rich surface functionality. In this review, we correlate the structural features of CDs with their optical and electronic properties and evaluate key properties for efficient solar energy-conversion applications with an emphasis on photocatalysis and photoelectrocatalysis, to shed some light on designing high performance CD-based photosystems. Solar hydrogen production from catalytic water splitting is one of the many options available to help generate clean power and alleviate the threatening environmental concerns stemming from the use of fossil fuels. During the past decade, carbon dots (CDs) have shown great potential in their application for solar-driven hydrogen production owing to their exceptional photophysical and electrical properties derived from their sp2/sp3 hybridized core structure and rich surface functionality. In this review, we correlate the structural features of CDs with their optical and electronic properties and evaluate key properties for efficient solar energy-conversion applications with an emphasis on photocatalysis and photoelectrocatalysis, to shed some light on designing high performance CD-based photosystems. a combination of two structures. the intentional introduction of heteroatomic impurities is called doping. Some impurities can provide extra electrons to modulate the electronic properties of the doped materials. Those modulations are called electron-doping effect. a material acts as an electron shuttle between two systems to facilitate the electron transfer. a fluorescent chemical compound that can re-emit light upon light excitation, which typically contains several fused aromatic groups, or planar or cyclic molecules with several π bonds. a process whereby photo-generated charge carriers recombine while releasing phonons instead of photons, which lowers the fluorescent quantum yield and increases heat losses. a way of describing bonding in certain molecules by the combination of several contributing structures. In those structures, the electrons are delocalized across different orbitals. a reversible hydrogen electrode is a reference electrode, the measured potential of which changes with pH and is expressed with the equation: E0 = 0.000 − 0.059 × pH. The applied potential versus other types of reference electrode are usually converted to RHE for clarity. describing a crystal structure (typically for graphite) in which basal planes have slipped out of alignment.