Scientists Achieve Light-Driven Hydrogen Dissociation at Room Temperature

Recently, the team of Researcher Wang Feng and Associate Researcher Luo Nengchao from the Bioenergy Chemicals Research Group (DNL0603 Group) of the Bioenergy Research Department of our institute, in collaboration with Researchers Zhang Fuxiang, Xiao Jianping, Li Rengui, Liu Wei, Chen Ruotian, Professor Paolo Fornasiero of the University of Trieste, Italy, and Professor Wang Guoxiong of Fudan University, have made important progress in the field of photocatalytic hydrogen heterolytic cracking, achieving hydrogen heterolytic cracking at room temperature.

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Hydrogenation is a crucial reaction in the chemical industry, with approximately 25% of chemical reactions involving at least one hydrogenation step. A key component of hydrogenation is hydrogen activation, which involves both homolytic and heterolytic cleavage mechanisms. Heterolytic cleavage produces polar hydrogen species, which are highly reactive and selectively hydrogenate polar functional groups. However, heterolytic cleavage generally requires relatively high reaction temperatures, and due to the low concentration of reactive sites, the reaction rate is low, making it the rate-determining step in hydrogenation reactions.

Active sites for hydrogen heterolytic scission include various types, but their essential structural characteristic is the presence of spatially proximal (subnanometer-scale) positive and negative charge centers. In this work, Wang Feng's team, building on their previous work in which photogenerated electrons and holes independently trigger half-reactions ( Nature Energy , 2019 ; Nature Catal. , 2020 ; J. Am. Chem. Soc. , 2022 ; Joule , 2023 ; Angew. Chem. Int. Ed. , 2023 ; Nature Synth. , 2024 ; J. Am. Chem. Soc. , 2024 ; Angew. Chem. Int. Ed. , 2025 ), proposed using photogenerated electrons and holes to construct spatially proximal positive and negative charge centers, enabling hydrogen heterolytic scission at room temperature. This research has overcome the key scientific difficulty of constructing spatially proximal bound states of electrons and holes. While utilizing electron - hole pairs to catalyze hydrogen heteroscission, it has effectively avoided the problem of electron - hole recombination due to spatial proximity.

Researchers used gold / titanium dioxide ( Au/TiO2 ) as a model catalyst and excited TiO2 with ultraviolet light . Their findings suggest that photoexcited electrons can migrate to Au nanoparticles and become bound. Simultaneously, due to the presence of Au-O-Ti defect states at the interface between the Au nanoparticles and TiO2 , photogenerated holes are trapped at the interface. The researchers found that, with holes and electrons located at the Au-O-Ti interface and Au nanoparticles, respectively, bound electron - hole pairs are formed in close proximity. The simultaneous presence of a thermocatalytic hydrogen heterolytic splitting mechanism on Au/TiO2 at room temperature, combined with the photocatalytic hydrogen heterolytic splitting mechanism on Au/ TiO2 , led researchers to observe that the reaction activity initially decreases and then increases linearly with increasing light intensity.

Furthermore, the team applied this photocatalytic hydrogen heterolytic splitting method to carbon dioxide ( CO₂ ) reduction, achieving a single-pass CO₂ conversion rate of nearly 100% in a photocatalytic fixed-bed reactor , with ethane as the main product, a selectivity greater than 99% , and photocatalytic CO₂ hydrogenation stability exceeding 1500 hours. By connecting an ethane dehydrogenation to ethylene unit in series, the team achieved CO₂ hydrogenation to ethylene, with a single-pass yield greater than 99 % . This photocatalytic hydrogen heterolytic splitting method can be extended to systems such as Au/N-TiO₂ , Au /CeO₂ , and Au/BiVO₄ , and can also utilize sunlight to hydrogenate CO₂ to ethane, with a selectivity of 90% .

The research results, titled “Photochemical H₂ dissociation for nearly quantitative CO₂ reduction to ethylene,” were recently published in Science. This work was supported by the National Natural Science Foundation of China, the Dalian High-level Talent Innovation Support Program, the Liaoning Provincial Outstanding Youth Fund, the Liaoning Binhai Laboratory Fund, the Chinese Academy of Sciences Youth Promotion Association, and the Institute’s Innovation Fund.Article link: https://doi.org/10.1126/science.adq3445