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Instruments / Technical Area	Publication Details	Published
B18-Core EXAFS	Covalent stabilization of copper porphyrin into carbon nitride for the catalytic reduction of CO2 Claudio Cometto , Giulia Marafon , Veronica Celorrio , Gonzalo Garcia , Steffi Y. Woo , Enrico Paron , Alberto Zobelli , Gregorio Bottaro , Lidia Armelao , Elena Pastor , Alessandro Moretto , Laura Calvillo Journal Of Catalysis 19 DOI: 10.1016/j.jcat.2024.115597 Diamond Proposal Number(s): [19850] Open Access Show Abstract ▼ Abstract: The development of active, selective, and durable (photo)electrocatalytic hybrid systems by combining molecular catalysts and semiconductor substrates is crucial for efficiently converting solar light into high-value products. Herein, a one-step synthesis method to obtain carbon nitride (CN) nanosheets, which allows the direct covalent polymerization with molecular catalysts, was developed. Copper-porphyrin (CuPor) units were embedded in the CN structure as a case-study. The single and hybrid materials were fully characterized by combining microscopic and spectroscopic techniques and tested as (photo)electrocatalysts for the CO2 reduction reaction (CO2RR) in aqueous solution. Experimental evidence confirmed an effective boost of the CN photoelectrocatalytic activity by introducing the CuPor units. Formate was identified as the only CO2RR product on both CuPor and CuPor-CN, simultaneously with hydrogen from the competitive hydrogen evolution reaction. However, the formate/hydrogen ratio was higher when the hybrid material was used as catalyst, suggesting a synergetic effect between CuPor and CN, that favors the CO2RR and hinders the HER. In addition, the stability of the CuPor units in the CN matrix under catalytic conditions was studied by in situ X-ray absorption. No changes of the Cu porphyrin structure or formation of copper clusters/nanoparticles was observed as a function of the applied potential nor after an accelerated ageing treatment, suggesting that the CN matrix is able to stabilize the Cu sites avoiding their agglomeration.	Aug 2024
B18-Core EXAFS	Insights into the active nickel centers embedded in graphitic carbon nitride for the oxygen evolution reaction Nicolò Rossetti , Aldo Ugolotti , Claudio Cometto , Veronica Celorrio , Goran Dražič , Cristiana Di Valentin , Laura Calvillo Journal Of Materials Chemistry A DOI: 10.1039/D3TA07389K Diamond Proposal Number(s): [28356] Open Access Show Abstract ▼ Abstract: Experimental and theoretical studies have demonstrated that the use of single atom catalysts (SACs) for energy conversion processes is very promissing. However, their stability under catalytic conditions is the main issue that hinders their commercial use. In this work, we report an oxygen evolution catalyst based on single nickel atoms stabilized in triazine-based carbon nitride (CN) and a detailed study of the evolution of the Ni centers under catalytic conditions. The nanostructured materials have been characterized by combining experimental techniques, such as X-ray diffraction, transmission electron microscopy, X-ray absorption and X-ray photoemission spectroscopy, with DFT theoretical calculations to determine the CN structure, the metal adsorption sites, the coordination of the Ni atoms, as well as the changes undergone under catalytic conditions. Electrochemical characterization showed a linear increase of the catalytic activity with the Ni loading. The stability of the materials was studied by HR-TEM and XAS post-catalysis measurements and DFT simulations. Results indicated a partial chemical restructuration of the single Ni atoms under catalytic conditions with the formation of Ni-O-Ni moieties, stabilized in the CN cavities, which are the real catalytic species.	Feb 2024
B18-Core EXAFS	Copper single-atoms embedded in 2D graphitic carbon nitride for the CO2 reduction Claudio Cometto , Aldo Ugolotti , Elisa Grazietti , Alessandro Moretto , Gregorio Bottaro , Lidia Armelao , Cristiana Di Valentin , Laura Calvillo , Gaetano Granozzi Npj 2d Materials And Applications 5 DOI: 10.1038/s41699-021-00243-y Diamond Proposal Number(s): [25902] Open Access Show Abstract ▼ Abstract: We report the study of two-dimensional graphitic carbon nitride (GCN) functionalized with copper single atoms as a catalyst for the reduction of CO2 (CO2RR). The correct GCN structure, as well as the adsorption sites and the coordination of the Cu atoms, was carefully determined by combining experimental techniques, such as X-ray diffraction, transmission electron microscopy, X-ray absorption, and X-ray photoemission spectroscopy, with DFT theoretical calculations. The CO2RR products in KHCO3 and phosphate buffer solutions were determined by rotating ring disk electrode measurements and confirmed by 1H-NMR and gas chromatography. Formate was the only liquid product obtained in bicarbonate solution, whereas only hydrogen was obtained in phosphate solution. Finally, we demonstrated that GCN is a promising substrate able to stabilize metal atoms, since the characterization of the Cu-GCN system after the electrochemical work did not show the aggregation of the copper atoms.	Jul 2021

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