Highly Efficient Electron Transfer in a Carbon Dot–Polyoxometalate Nanohybrid

Abstract

Using solar radiation to fuel catalytic processes is often regarded as the solution to our energy needs. However, developing effective photocatalysts that are active under visible light has proven to be difficult, often due to the toxicity, instability, and high cost of suitable catalysts. We engineered a novel photoactive nanomaterial obtained by the spontaneous electrostatic coupling of carbon nanodots with [P2W18O62]6–, a molecular catalyst belonging to the class of polyoxometalates. While the former are used as photosensitizers, the latter was chosen for its ability to catalyze reductive reactions such as dye decomposition and water splitting. We find the electron transfer within the nanohybrid to be so efficient that a charge-separated state is formed within 120 fs from photon absorption. These results are a cornerstone in the engineering of a new class of nanodevices, which are nontoxic, are inexpensive, and can carry out solar-driven catalytic processes.

Ultrafast Interface Charge Separation in Carbon Nanodot–Nanotube Hybrids

“…Today, nanotechnologies could provide new answers to these old problems. In particular, coupling nanomaterials with different electronic characteristics into a single device provides fundamentally new routes in materials science to develop efficient nano-photoelectrodevices for artificial photosynthesis, photocatalysis, and photovoltaics. − Crucial requirements for these applications are the use of low cost materials and the possibility of sensitively controlling their characteristics to allow the fine tuning of the devices . Carbon-based nanomaterials are an area of huge interest in nanoscience motivated by their unsurpassed chemical versatility and diverse electronic properties which can be finely tailored for applications.…”

Assessing the Photoinduced Electron-Donating Behavior of Carbon Nanodots in Nanoconjugates

“…8 In this regard, CNDs have been decorated with photo-and redox-active building blocks for energy and/or charge transfer processes, artificial photosynthesis, and, more recently, solar energy conversion devices. 9,10 Leading examples are the combination with SWCNTs, 11 polyoxometalates, 12 or transition metal dichalcogenides. 13 CNDs have been covalently grafted with electron-donating π-extended tetrathiafulvalenes, 14 phthalocyanines, 15 and porphyrins.…”

“…An important feature of CNDs is their duality in charge transfer events acting either as electron donor or as electron acceptor . In this regard, CNDs have been decorated with photo- and redox-active building blocks for energy and/or charge transfer processes, artificial photosynthesis, and, more recently, solar energy conversion devices. , Leading examples are the combination with SWCNTs, polyoxometalates, or transition metal dichalcogenides …”

Interfacing Carbon Dots for Charge‐Transfer Processes

“…[59] Finally, a recent study demonstrated the photoinduced electron transfer from CDs to [P 2 W 18 O 62 ] 6− polyoxometalate arrays, expanding the field of nanostructures being so far interfaced with these unique fluorescent carbon nanoparticles. [74] In this case, the pH-tunable surface charge of CDs enabled the development of attractive electrostatic forces with the negatively charged [P 2 W 18 O 62 ] 6− . The utilized CDs were derived by nitration of a pyrene powder, followed by an alkaline hydrothermal treatment.…”