Unravelling the photo-excited chlorophyll-a assisted deoxygenation of graphene oxide: formation of a nanohybrid for oxygen reduction

Abstract

We tried to expand the horizon of graphene oxide (GO) reduction methods through chlorophyll-a (CHL-a) molecules which is inclined to react favourably with GO by virtue of photo excited electron transfer from singlet excited CHL-a LUMO [-0.7volt] to GO [-0.4] in aqueous media favoured by the interactive affinity between CHL-a and reduced graphene oxide (RGO), which is ensured through π-π interaction between CHL-a macro-cycle and GO surface, resulting in the formation of CHL-a + radical cation which might favor the oxidation of water with oxygen evolution. The formation of RGO after photo-exposure also can be confirmed via TEM and Raman spectra measurement. Gradual restoration of sp2 hybridisation in GO frame work with increasing CHL-a concentration can be correlated with the enhanced contribution of the conformation in which electron transfer is efficient from CHL-a to GO, [also supported by XPS and XRD data] this fact corroborates the faster component augmentation towards overall excited state life time. The applicability of this GO/CHL-a nanohybrid as a possible electro-catalyst, to be used for oxygen reduction in energy conversion systems such as fuel cell has also been explored through cyclic voltammetry. All these results cumulatively highlight towards an effective environment friendly mechanism of the photoexcited CHL-a assisted deoxygenation of GO in aqueous media, which eventually give rise to RGO/CHL-a nano-hybrid as an potential electro-catalyst in next generation bio-fuel cell.Restoration of sp2 hybridization in GO framework where photo excited electron can be transferred from CHL-a to GO and can be ensured via π interactive affair between CHL-a and RGO surface, resulting in a formation of RGO\CHL-a nano hybrid, where CHL-a cation stabilised itself by accepting electron from aqueous environment and eventually give rise to an efficient electron transfer nano hybrid catalyst in next generation bio-fuel cell.

Phase Transition and Anisotropic Transport of MoS 2 /Chlorophyll Van der waal Heterostructure Formed via Biomimetic Photo-electron Donation

“…The In the 2H MoS2/CHL-a hybrid [without photo-exposure], Mo 3p peak at 395.2eV partially overlaps with N1S spectra of CHL-a, at a binding energy of 398.1-398.9 eV [Fig. 2(i)] which is characteristic of the pyrrolidine nitrogen atoms of the porphyrinmacro-cycle 27 . We found a second peak (N-2), a shoulder, at 400 eV after photoexposure [Fig.…”

Electrodeposited Nickel Coating Reinforced with Chlorophyll‐Reduced Graphene Oxide

“…RGO CHL reduction potential is around −1.7 V (due to complexation). [ 16 ] Charge distribution over the self‐assembled CHL molecules plays an important role in determining the electrochemical behavior of CHL‐RGO. Polarization of porphyrins is possible due to the presence of large π systems.…”

“…It can be expected that because of the tendency to maximize the π bonding on the RGO surface, a flat orientation is assumed to have been adopted by the large planar π systems. [ 16 ] In this potential range and lower current density, enhanced surface diffusion allows the CHL‐RGO to assemble in ordered arrays mainly driven by CHL self‐assembly dynamics as evident from auger and scanning electron microscopy (SEM) analysis ( Figure ), resulting in homogeneous distribution over surface at 0.1 A cm −2 current density. Eventually, heavier CHL‐RGO gets sufficient time to be deposited even at small overpotential.…”

Biomimetic complexes‐graphene composites for redox processes

“…This structure had good activity in ORR through 4‐electron pathway to water without the formation of H 2 O 2 . In addition, various non‐covalently immobilized natural and synthetic porphyrins on different types graphene such as chlorophyll‐a/GO, Ni and Co Por/rGO as bifunctional catalyst, multilayers Mn, Fe and Co por/GO composites, and metal porphyrin (Fe, Co, Ni, and Mn) on poly (sodium‐p‐styrenesulfonate) modified reduced graphene oxide, were have been synthesized as ORR catalyst.…”