New robust and effective molecular hybrid material for electrocatalytic water oxidation at neutral pH

By October 25, 2023October 26th, 2023ICIQ

Prof. Antoni Llobet’s research group at the BIST Community centre ICIQ has published in Advanced Materials the first example of a molecular water oxidation catalyst based on first row transition metal complex anchored on a conductive solid support, which maintains its molecular integrity after more than 11.000 TONs. This breakthrough has applications in solar fuels and conversion of solar energy into chemical products.

Investigating solar fuels is vital as it offers a pathway to harnessing renewable energy from the sun to produce clean and sustainable fuel sources. The research in this field holds the potential to reduce our reliance on fossil fuels, mitigate environmental impact, and advance our journey toward a greener, more sustainable future.

Using sunlight to split water holds great promise for the shift from fossil to solar fuels,” highlights Prof. Antoni Llobet. His research group at the Institute of Chemical Research of Catalonia (ICIQ) develops water oxidation catalysts inspired by nature’s structural motives and reactivity strategies. Highly performant and robust catalysts have been developed based on ruthenium (Ru) complexes. However, as Prof. Llobet explains, “given the scarcity of Ru in nature, to ensure sustainability we need to develop high-performance complexes based on abundant first-row transition metals which at present are basically inexistent except for a very few copper (Cu) complexes.”

The present work, developed in collaboration with an Italian team at Università di Bologna, reports the creation of a molecular hybrid material, based on a molecular Cu water oxidation catalyst anchored on graphitic electrodes. This hybrid material represents the most robust molecular water oxidation catalysts anchored on a conductive surface based on a first-row transition metal, which maintains its integrity and activity over more than 11,000 TONs, as demonstrated by several techniques. Furthermore, this hybrid material works under neutral pH as opposed to most water oxidation catalyst based on iron (Fe) or nickel (Ni) oxides that need to work under extremely basic pH. Moreover, the foot of the catalytic waves starts at approx. 1.07 V that represents a very low overpotential of only 250 mV.

Electropolymerization of thiophene monomer, containing a covalently attached Cu molecular water oxidation catalyst, on graphitic surfaces generates powerful and robust molecular anodes. Turnover numbers higher than 11,000 are achieved for the oxygen evolution reaction at low overpotentials of approx. 250 mV.

This study opens the door to employing hybrid materials as catalysts in electrochemical and photoelectrochemical water-splitting devices. This breakthrough extends to the field of solar fuels and more broadly to applications in converting solar energy into chemical products,” declares Dr. Carlos Garcia Bellido, one of the authors of the paper and postdoctoral researcher in Prof. Llobet’s group.

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101006839 (CONDOR).

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ICIQ press release