Knitting the Catalytic Pattern of Artificial Photosynthesis to a Hybrid Graphene Nanotexture

Abstract

The artificial leaf project calls for new materials enabling multielectron catalysis with minimal overpotential, high turnover frequency, and long-term stability. Is graphene a better material than carbon nanotubes to enhance water oxidation catalysis for energy applications? Here we show that functionalized graphene with a tailored distribution of polycationic, quaternized, ammonium pendants provides an sp(2) carbon nanoplatform to anchor a totally inorganic tetraruthenate catalyst, mimicking the oxygen evolving center of natural PSII. The resulting hybrid material displays oxygen evolution at overpotential as low as 300 mV at neutral pH with negligible loss of performance after 4 h testing. This multilayer electroactive asset enhances the turnover frequency by 1 order of magnitude with respect to the isolated catalyst, and provides a definite up-grade of the carbon nanotube material, with a similar surface functionalization. Our innovation is based on a noninvasive, synthetic protocol for graphene functionalization that goes beyond the ill-defined oxidation-reduction methods, allowing a definite control of the surface properties.

Electrochemical Systems for Renewable Energy Conversion from Salinity and Proton Gradients

“…These compounds consist of anionic transition metal molecular oxides where the transition metals present high oxidation states. 69 This configuration has attracted the interest of different scientific areas and can be applied in catalysis, 70 energy conversion, 71 and molecular electronics. 72 The basal structure of these materials consists of a tetrahedral nucleus surrounded by twelve MO 6 octahedral units that share their edges and vertices.…”

Coordination chemistry on carbon surfaces

“…Generation of positive charges onto the CNT surface was also carried out by covalent grafting of 2-aminoethylammonium chloride allowing the immobilization of an oxygen-evolving tetra-ruthenium polyoxometalate affording a nanomaterial for electrocatalytic water splitting [246]. This strategy was then extended to few layer graphene that was functionalized by covalent addition of 4-amino-N,N,N-trimethylbenzene ammonium [247] or with a tailored distribution of polycationic, quaternized, ammonium, using a first generation polyaminoamide dendron [248], yielding an innovative FLG platforms with positive charges to immobilize inorganic polyanions.…”

Efficiency of Polyoxometalate-Based Mesoporous Hybrids as Covalently Anchored Catalysts

“…3,5−10 This strategy has also been recently applied to surface-modified graphene. 11 POMs may also be immobilized successfully into materials through various other strategies 12 such as their encapsulation into metal−organic frameworks (MOFs), 13,14 their intercalation into layered double hydroxides, 15 or their one-pot embedding into a silica matrix via co-condensation sol−gel methods 16 (including the covalent grafting of vacant POMs into the walls of hybrid supports). 17,18 We recently focused on the elaboration of new mesoporous materials functionalized with nucleophilic (vacant) POMs for applications in the field of anchored homogeneous catalysis.…”