Bioinspired hollow semiconductor nanospheres as photosynthetic nanoparticles

Abstract

natural photosynthesis occurs in the thylakoid membrane where functional proteins and electron carriers are precisely arranged to efficiently convert sunlight into a chemical potential between the two membrane sides, via charge separation and electron transport chains, for use in oxygen generation and Co 2 fixation. These light-harvesting complexes and cofactors have been actively mimicked using dyes, semiconductors and catalytic nanoparticles. However, the photosynthetic scaffold that optimizes both the capture and distribution of light and separates both the oxidative and reductive species has been mimicked much less often, especially using polymer substances. Here we report the synthesis of hollow nanospheres sized in the optical range and made of a robust semiconductor, melon or carbon-nitride polymer. These hollow nanospheres are shown to function as both light-harvesting antennae and nanostructured scaffolds that improve photoredox catalysis, which was determined to have a 7.5% apparent quantum yield via a hydrogen-generation assay.

Contribution of multiple reflections to light utilization efficiency of submicron hollow TiO2 photocatalyst

“…For example, Li et al [21] found that the photocatalytic activity of the ''semi-hollow'' core-shell structured TiO2 increased compared to the ''fully-hollow'' structured TiO2, suggesting that the multiple reflections of the incident light within the interior cavity of the hollow structure resulted in an enhanced light harvesting efficiency. This claim of enhancement of the photocatalytic activity by multiple reflections was echoed by others for TiO2 hollow structures [22][23][24][25], and also claimed later for other hollow materials such as ZnO [26,27], NiO [28], SnO [29], CdS [30], Fe2O3 [31] and carbon nitride [32]. However, as generally known, the multiple reflections within the interior cavity should occur only when the cavity diameter is much larger than the wavelength of the incident light [33,34].…”

Dendritic Tip-on Polytriazine-Based Carbon Nitride Photocatalyst with High Hydrogen Evolution Activity

“…22 In photocatalysis, particularly when using CN photocatalysts, morphology and surface area, in relation to the effective charge separation, are important parameters. [23][24][25][26][27][28][29][30] Density functional theory (DFT) is a useful and powerful technique to obtain the relevant photophysical and optoelectronic parameters of a given photocatalyst. 31,32 In addition to structure determination, DFT calculations can lead to the simulation of several semiconductor properties such as the bandgap, the dielectric constants and band positions, with good accuracy thanks to recently developed functionals such as HSE06.…”

Oxygenic photosynthesis: translation to solar fuel technologies

“…12) function not only as nanostructured scaffold for the Pt co-catalyst but also as the light-harvesting antennae that facilitate photoreduction catalysis. Significantly, such sophisticated highly nanostructured assemblies of optimized thickness have been shown to operate at an impressive solar-to-hydrogen quantum efficiency of 7.5% [92]. Hollow polymerized nanospheres with controlled surface functionalities and shell thickness provide an important development in artificial photosynthesis field as they can act as a platform for assembling various functionalities into complex nanostructures, while at the same time maintaining "interior" and "exterior" compartments, with a "membrane" separating both of them.…”

“…This light-harvesting nanosphere of the precisely controlled thickness serves as a photocatalytically active scaffold for immobilization of the metal co-catalyst resulting in both water splitting and molecular hydrogen production under visible light illumination and reaching a solar-to-hydrogen quantum efficiency of 7.5%. Reproduced with permission from Sun et al [92].…”

“…The work is an excellent proof-of-concept example illustrating that the oriented immobilization of photosynthetic modules with the appropriate electrode is a prerequisite for enhanced direct electron transfer and improved robustness of the biohybrid PEC system. An interesting approach in the construction of the biohybrid H 2 -producing nanodevices is based on application of nanostructured hollow nanospheres sized in the optical range and composed of Pt-doped carbon nitride organic semiconductor exhibiting both water splitting or proton reduction activity [92]. These small, hollow semiconducting nanospheres (Fig.…”