Periodic Reporting for period 1 - Photo2Olef (Photo-assisted Light Alkanes Dehydrogenation to Olefines Under Mild Conditions with Trimetallic clusters Confined in Zr-based MOFs as the Catalyst)
Reporting period: 2023-07-01 to 2025-06-30
To address the pressing need for sustainable and low-emission chemical manufacturing, this project aims to develop advanced catalytic systems for solar-assisted C-H activation, a central challenge in green chemistry. The ability to break and transform C-H bonds under mild conditions enables the conversion of abundant, low-value feedstocks into fuels and platform chemicals, while minimizing energy input and CO2 emissions.
Originally, the project focused on photothermal dehydrogenation of light alkanes using trimetallic catalysts confined in porous frameworks. These catalysts were designed to efficiently capture light and promote bond activation, with the dual goal of olefin and hydrogen production under ambient conditions. This approach directly supports the EU’s ambition for clean hydrogen and electrified chemical processes.
As the project progressed, the research was expanded and refined based on experimental findings, to explore broader but mechanistically related C–H activation pathways. This included:
(1) Photocatalytic dehydrogenation of formic acid to produce H2.
(2) The investigation of proton transfer process in photocatalytic H2 evolution systems in the presence of organic molecules as the electron donor.
(3) A novel photo-assisted transformation of methyl tert-butyl ether (MTBE) into ethylene glycol, coupled with hydrogen evolution.
These directions remain tightly aligned with the project’s core objectives: utilizing solar energy for catalytic C-H activation, producing green hydrogen, and enabling low-temperature chemical transformations using innovative materials. By maintaining the focus on solar-driven catalysis and sustainable hydrogen generation, the project continues to contribute directly to climate goals and the decarbonization of the chemical sector.
Originally, the project focused on photothermal dehydrogenation of light alkanes using trimetallic catalysts confined in porous frameworks. These catalysts were designed to efficiently capture light and promote bond activation, with the dual goal of olefin and hydrogen production under ambient conditions. This approach directly supports the EU’s ambition for clean hydrogen and electrified chemical processes.
As the project progressed, the research was expanded and refined based on experimental findings, to explore broader but mechanistically related C–H activation pathways. This included:
(1) Photocatalytic dehydrogenation of formic acid to produce H2.
(2) The investigation of proton transfer process in photocatalytic H2 evolution systems in the presence of organic molecules as the electron donor.
(3) A novel photo-assisted transformation of methyl tert-butyl ether (MTBE) into ethylene glycol, coupled with hydrogen evolution.
These directions remain tightly aligned with the project’s core objectives: utilizing solar energy for catalytic C-H activation, producing green hydrogen, and enabling low-temperature chemical transformations using innovative materials. By maintaining the focus on solar-driven catalysis and sustainable hydrogen generation, the project continues to contribute directly to climate goals and the decarbonization of the chemical sector.
During the fellowship period, the research activities were centered around the development of light-driven catalytic systems for sustainable hydrogen production and green chemical synthesis. The project addressed the mechanistic understanding and technological challenges of photocatalytic C-H activation and dehydrogenation reactions under mild conditions. The work was structured into three interconnected research themes:
1. Clarifying the Proton Source in Photocatalytic Hydrogen Evolution
Photocatalytic hydrogen evolution is commonly reported using sacrificial organic donors (e.g. alcohols, amines), but the origin of the proton in the generated H2 is often unclear. This project established a protocol to distinguish between real water splitting and sacrificial donor dehydrogenation by employing deuterium labelling strategies using tetrahydrofuran (THF) as the sacrificial donor.
Approach & Methodology: A TiO2-based photocatalyst was tested using THF as the sacrificial reagent. Due to THF’s low acidity and absence of rapid H/D exchange, it allowed precise tracing of proton sources in the reaction via isotope labelling experiments.
Key Findings:
(a) Under low-water conditions, both water and THF contributed protons for H2 evolution.
(b) Water acted as a proton shuttle while THF served as both electron and proton donor.
The findings clarified misconceptions in many reported water-splitting systems and established criteria for evaluating true photocatalytic water splitting.
Publication: Angew. Chem. Int. Ed. 2024, 63, e202408626.
2. Photocatalytic Upgrading of MTBE into Ethylene Glycol Coupled with Hydrogen Production
This task focused on developing a sustainable route to ethylene glycol (EG), an essential commodity chemical, by photocatalytically transforming methyl tert-butyl ether (MTBE), which can be regarded as hydroxyl group protected methanol, to produce ethylene glycol by two consecutive steps.
Catalyst Development: A novel Pt/TiO2 catalyst with co-existing anatase and rutile phases was synthesized to enhance hot electron/hole separation.
Performance: Achieved a high turnover frequency (>2700 h⁻¹) and 67% selectivity toward EG under UV–visible light (320–500 nm) at ambient conditions.
Process Intensification: A major milestone was the transition from batch-scale reactions to a continuous circulation reactor, demonstrating feasibility beyond the lab scale. The reactor operated continuously for 130 hours, yielding 13 g of EG dimer and 1.9 L of hydrogen, with a sustained MTBE conversion of 58%. The hydrolysis of the dimer product afforded ethylene glycol in >99% yield, validating the downstream conversion step.
Mechanism: Radical intermediates were identified via EPR and TEMPO trapping experiments, confirming a radical-based pathway.
Outcome: Demonstrated practical scalability and potential industrial relevance for green EG production from an environmental contaminant.
Publications: Nature Communications 2025, 16 (1), 1-11
3. Light-Driven Hydrogen Release from Formic Acid and Integration with Enzymatic Hydrogenation
In addition to valorising oxidation products, the project also explored an alternative route for sustainable hydrogen production via liquid organic hydrogen carriers (LOHCs). Among LOHCs, formic acid is particularly attractive due to its high hydrogen content. This segment of the project focused on evaluating photocatalytic decomposition of formic acid under mild conditions to enable on-demand H2 generation, with the goal of coupling this hydrogen release to downstream enzymatic hydrogenation reactions.
Catalyst Development and performance: A Pt@TiO2 catalyst was synthesized. Under optimized conditions, the system exhibited high activity for photocatalytic FA dehydrogenation. On-off light experiments confirmed the strict light-driven hydrogen evolution, with minimal thermal contribution, highlighting the potential for light-controlled H2 release from FA.
Outcome: This work demonstrated the integration of LOHC photodecomposition with enzymatic catalysis and established a novel hybrid platform for light-driven hydrogenation at mild conditions, expanding the technological reach of solar hydrogen.
1. Clarifying the Proton Source in Photocatalytic Hydrogen Evolution
Photocatalytic hydrogen evolution is commonly reported using sacrificial organic donors (e.g. alcohols, amines), but the origin of the proton in the generated H2 is often unclear. This project established a protocol to distinguish between real water splitting and sacrificial donor dehydrogenation by employing deuterium labelling strategies using tetrahydrofuran (THF) as the sacrificial donor.
Approach & Methodology: A TiO2-based photocatalyst was tested using THF as the sacrificial reagent. Due to THF’s low acidity and absence of rapid H/D exchange, it allowed precise tracing of proton sources in the reaction via isotope labelling experiments.
Key Findings:
(a) Under low-water conditions, both water and THF contributed protons for H2 evolution.
(b) Water acted as a proton shuttle while THF served as both electron and proton donor.
The findings clarified misconceptions in many reported water-splitting systems and established criteria for evaluating true photocatalytic water splitting.
Publication: Angew. Chem. Int. Ed. 2024, 63, e202408626.
2. Photocatalytic Upgrading of MTBE into Ethylene Glycol Coupled with Hydrogen Production
This task focused on developing a sustainable route to ethylene glycol (EG), an essential commodity chemical, by photocatalytically transforming methyl tert-butyl ether (MTBE), which can be regarded as hydroxyl group protected methanol, to produce ethylene glycol by two consecutive steps.
Catalyst Development: A novel Pt/TiO2 catalyst with co-existing anatase and rutile phases was synthesized to enhance hot electron/hole separation.
Performance: Achieved a high turnover frequency (>2700 h⁻¹) and 67% selectivity toward EG under UV–visible light (320–500 nm) at ambient conditions.
Process Intensification: A major milestone was the transition from batch-scale reactions to a continuous circulation reactor, demonstrating feasibility beyond the lab scale. The reactor operated continuously for 130 hours, yielding 13 g of EG dimer and 1.9 L of hydrogen, with a sustained MTBE conversion of 58%. The hydrolysis of the dimer product afforded ethylene glycol in >99% yield, validating the downstream conversion step.
Mechanism: Radical intermediates were identified via EPR and TEMPO trapping experiments, confirming a radical-based pathway.
Outcome: Demonstrated practical scalability and potential industrial relevance for green EG production from an environmental contaminant.
Publications: Nature Communications 2025, 16 (1), 1-11
3. Light-Driven Hydrogen Release from Formic Acid and Integration with Enzymatic Hydrogenation
In addition to valorising oxidation products, the project also explored an alternative route for sustainable hydrogen production via liquid organic hydrogen carriers (LOHCs). Among LOHCs, formic acid is particularly attractive due to its high hydrogen content. This segment of the project focused on evaluating photocatalytic decomposition of formic acid under mild conditions to enable on-demand H2 generation, with the goal of coupling this hydrogen release to downstream enzymatic hydrogenation reactions.
Catalyst Development and performance: A Pt@TiO2 catalyst was synthesized. Under optimized conditions, the system exhibited high activity for photocatalytic FA dehydrogenation. On-off light experiments confirmed the strict light-driven hydrogen evolution, with minimal thermal contribution, highlighting the potential for light-controlled H2 release from FA.
Outcome: This work demonstrated the integration of LOHC photodecomposition with enzymatic catalysis and established a novel hybrid platform for light-driven hydrogenation at mild conditions, expanding the technological reach of solar hydrogen.
This project advanced light-driven catalysis by (1) establishing a reliable deuterium-labelling protocol to clarify the true proton source in photocatalytic hydrogen evolution, addressing a long-standing mechanistic gap, highlighting the importance of focusing on value-added oxidation products besides the efficiency of hydrogen production; (2) developing a novel and scalable photocatalytic route to ethylene glycol from MTBE under mild conditions, in contrast to current industrial processes that heavily rely on coal/petroleum resource under harsh reaction conditions. The project demonstrates real-world applicability through process intensification; and (3) enabling on-demand hydrogen release from formic acid using light, successfully integrated with enzymatic hydrogenation for fine chemical synthesis. These outcomes go beyond the state of the art by coupling selective oxidation product valorization with sustainable H2 generation. Further steps include pilot-scale demonstrations, life cycle analysis, and potential Intellectual properties protection to facilitate industrial uptake and commercialization.