Hydrogen Evolution Reaction Mechanisms on Organic-Inorganic Perovskites

Wang, L., Xiao, H., Cheng, T., Li, Y., Goddard, W. A. Pb-Activated Amine-Assisted Photocatalytic Hydrogen Evolution Reaction on Organic–Inorganic Perovskites. Journal of the American Chemical Society, DOI: 10.1021/jacs.7b12028 (2018).


In this publication, researchers investigated the reaction mechanism for explicit aqueous solvent quantum mechanics (QM) studies determining the energetics and reaction barriers for the photocatalytic hydrogen evolution reaction (HER) on CH3NH3PbI3 surface. They found that both the lead (Pb) atoms and the surface organic molecules play essential roles, leading to a two-step Pb-activated amine-assisted (PbAAA) reaction mechanism involving an intermediate lead hydride state. Both H of H2 product are extracted from surface organic molecules, while two protons from the solution migrate along water chains via the Grotthuss mechanism to replace the H in organic molecule. Researchers obtain a reaction barrier of 1.08 eV for photochemical generation of H2 on CH3NH3PbI3 compared to 2.61 eV for the dark reaction. It is likely that this HER mechanism can also apply to the other organic perovskites, but the energy barriers and reaction rates may depend on the basicity of electrolyte and intrinsic structures of perovskites.

Contact: wag@wag.caltech.edu

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Reprinted from Wang, L., Xiao, H., Cheng, T., Li, Y., Goddard, W. A. Pb-Activated Amine-Assisted Photocatalytic Hydrogen Evolution Reaction on Organic–Inorganic Perovskites. Journal of the American Chemical Society,  DOI: 10.1021/jacs.7b12028  (2018).   Four possible reaction pathways for photocatalytic H2 generation on the MAPbI3 surface. The upper figure illustrates which H precursors form the H2  product, whereas the lower figure shows the structural model and  origins of reactants. The two purple balls are the doped potassium  atoms.

Reprinted from Wang, L., Xiao, H., Cheng, T., Li, Y., Goddard, W. A. Pb-Activated Amine-Assisted Photocatalytic Hydrogen Evolution Reaction on Organic–Inorganic Perovskites. Journal of the American Chemical Society, DOI: 10.1021/jacs.7b12028 (2018).

Four possible reaction pathways for photocatalytic H2 generation on the MAPbI3 surface. The upper figure illustrates which H precursors form the H2 product, whereas the lower figure shows the structural model and origins of reactants. The two purple balls are the doped potassium atoms.