Tuning the dimensionality of organic–inorganic hybrid perovskites towards improved photocatalytic hydrogen production

Abstract

Three-dimensional (3D) and two-dimensional (2D) organic–inorganic hybrid perovskites (OIHPs) have demonstrated attractive potential for producing hydrogen fuel via the photocatalytic pathway. However, the highly dynamic dissolution behaviour of 3D OIHPs in aqueous solution and the inferior light absorption and low charge transfer efficiency of 2D OIHPs represent their respective challenges towards efficient photocatalysis. Herein, we introduce quasi-2D OIHPs, which contain a distribution of grains with dimensionality ranging from 2D to 3D towards alleviating this dilemma. We found that among (CH₃(CH₂)₃NH₃)₂(CH₃NH₃)_n−1Pb_nI_3n+1 (BA₂MA_n−1Pb_nI_3n+1, n = 1, 2, 3, ∞) perovskites, the quasi-2D perovskite BA₂MAPb₂I₇ exhibited the highest photocatalytic activity, which is ca. 1.9 times that of the 2D perovskite BA₂PbI₄ and 23.2 times that of the 3D perovskite MAPbI₃. Experimental investigations show that tuning the dimensionality of BA₂MA_n−1Pb_nI_3n+1 allows simultaneous modulation of the light absorption, charge transport efficiency and dynamic dissolution rate of these perovskites. An optimum balance between these factors was achieved on quasi-2D BA₂MAPb₂I₇, accounting for the highest photocatalytic activity among BA₂MA_n−1Pb_nI_3n+1. This work demonstrates the potential of dimensional engineering in optimizing the photocatalytic performance of OIHPs.