Tunable Surface-Functionalized Nanocatalysts for Artificial Photosynthesis
Laura Mallón a b c, Heting Hou a, Álvaro Lozano a, Ignacio Álvarez a, Jordi Creus a b c, Jonathan De Tovar a, Roger Bofill a, Karine Philippot b c, Jordi García-Antón a, Xavier Sala a
a Universitat Autònoma de Barcelona (UAB), Campus UAB, 08193, Bellaterra, Barcelona, Catalonia, Spain
b CNRS, LCC (Laboratoire de Chimie de Coordination), UPR8241, INPT, Université de Toulouse, UPS, Cedex 4, F-31077 Toulouse, France.
c Université Toulouse III - Paul Sabatier, France
Proceedings of International Conference on Frontiers in Electrocatalytic Transformations (INTERECT)
València, Spain, 2021 November 22nd - 23rd
Organizers: Elena Mas Marzá and Ward van der Stam
Poster, Laura Mallón, 035
Publication date: 10th November 2021

The interface between catalyst-ligand/(photo)electrode is a key factor affecting the final (photo)electrocatalytic activity and selectivity of a nanocatalyst. In this regard, the organometallic method is an efficient and versatile synthetic pathway to obtain well-controlled metal nanostructures from the mild decomposition of an organometallic complex under H2.[1] The formation of nanoparticles (NPs) from “naked” metal atoms is  controlled by the addition of stabilizers (i.e. Ligands, supports, etc.). Since only solvent molecules, stabilizing agents and/or hydrides can be present on the surface, this methodology allows to obtain clean and flawless NPs, which constitutes an advantage to study the influence of the stabilizing agents on their morphology, surface chemistry and related catalytic performance. Furthermore, recent studies in our group confirmed the effect of capping ligands at the surface of Ru NPs to induce electronic changes in the nanocatalyst, affecting the electrocatalytic activity of the overall material.[2] In fact, the effect of ligands in the M-H bond energy has been described for HER in several works obtaining a good correlation between experimental exchange current density values and the Gibbs adsorption free energy of hydrogen.[3]

The organometallic approach also allows to introduce supports in the synthetic reaction media, permitting the NPs to directly grow on the surface of (photo)electrodes. This strategy is an interesting way to improve NPs dispersion and avoid aggregation under catalytic turnover. However, the electron transfer process between the catalyst and the (photo)electrode must be mastered. In this regard, the OER performance of hybrid electrodes made of Co-based NPs and carbon fibers (bare or COOH-functionalized) have been recently studied and tailored in our group [4]. The use of two different synthetic procedures (in-situ and ex-situ) and different solvents as NPs (co)stabilizers, allowed to obtain valuable insights about the influence of the metal-ligand/support interface on OER electrodes. In addition, the key importance of mastering the electron transfer processes in OER photocatalysis has been shown by a hybrid dyad system made of a Co3O4 NP core decorated with RuII-polypyridyl complexes.[5] The covalent anchoring of the photosensitizer to the NP improved the electron transfer between both entities, avoiding back-electron transfer phenomena, yielding a hybrid system capable to photo-oxidize water into dioxygen in a more efficient manner.

Finally, the use of the organometallic approach for the synthesis of mpg-CN (mesoporous graphitic carbon nitride) - Pt NPs has allowed having clean, reproducible and stable surfaces of the supported NPs, decisive features to obtain an active and selective photocatalyst for CO2 reduction.[6] Both the addition of Pt to the organic semiconductor and the use of different metal loadings allow tuning the selectivity among the different possible carbon products.

 

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