(401ab) Gate-Controlled Light-Driven Proton Transport through Graphene Membrane

Selective transport of molecules through a one-atom-thick mass barrier, such as graphene, holds promise to revolutionize chemical separation processes.[1] The atomically thin films are capable of ultrafast separation,[2-3] leading to energy-efficient chemical processes and reduced capital costs. Furthermore, the unique optical properties of the graphene materials that can significantly enhance mass transport in the presence of light thereby further improving overall separation performance. Recent experiments demonstrated that proton transport through monolayer graphene can be accelerated by over an order of magnitude with low intensity illumination.[4] By leveraging the carbon-free (solar light) energy sources, the separation performance of proton can be enhanced by a factor of ten, which provides a more energy-saving membrane separation approach.

Herein, we elucidate the fundamentals of the enigmatic photo-proton phenomenon and achieve precise control over its enhanced effects [5]. We demonstrate tunable modulation of this light-driven proton transport across a range of the infrared spectrum with different voltage bias. Through photocurrent measurements and Raman spectroscopy, we revealed the photon-proton effects arises from voltage-controlled tuning of graphene’s Fermi energy. This energy level adjusted specific photo-excited electron populations, enabling selective enhancement or suppression of the proton transport rate through the monolayer graphene. These findings demonstrate a dependence between graphene’s electronic and proton transport properties, offering unprecedented insights into light-matter interactions at ultrathin membrane. These fundamental insights can stimulate several innovative promises to substantially reduce the energy consumption of the membrane separation process, therefore contributing to the energy-efficient industry transition and building a more sustainable society for the future.

References

[1] Wang, L.; Boutilier, M. S. H.; Kidambi, P. R.; Jang, D.; Hadjiconstantinou, N. G.; Karnik, R. Fundamental Transport Mechanisms, Fabrication and Potential Applications of Nanoporous Atomically Thin Membranes. Nature Nanotechnology 2017, 12, 509–522.

[2] S. Huang, S. Li, L. F. Villalobos, M. Dakhchoune, M. Micari, D. J. Babu, M. T. Vahdat, M. Mensi, E. Oveisi, K. V. Agrawal*, “Millisecond lattice gasification for high-density CO2- and O2-sieving nanopores in single-layer graphene”, Science Advances, 2021, 7, eabf0116.

[3] K.-J. Hsu, S. Li, M. Micari, H.-Y. Chi, L. F. Villalobos, S. Huang, X. Duan, A. Züttel, K. V. Agrawal*, “Pyridinic Nitrogen Substituted Two-Dimensional Pores for Rapid and Selective CO2 Transport.” Nature Energy, 2024, 9, 964.

[4] Lozada-Hidalgo, M. et al. Giant photoeffect in proton transport through graphene membranes. Nature Nanotechnology. 2018,13, 300–303.

[5] S. Huang†, E. Griffin†, J. Cai, B. Xin, J. Tong, Y. Fu, V. Kravets, F. M. Peeters, M. Lozada-Hidalgo, “Gate-controlled suppression of light-driven proton transport through graphene electrodes.” Nature Communications, 2023,14, 6932.