The solar-driven splitting of hydrohalic acids (HX) is an important and fast growing research direction for H2 production. In addition to the hydrogen, the resulting chemicals (X2/X3-) can be used to propagate a continuous process in a closed iodine-sulfur cycle and are themselves useful products. In an effort to develop a cost-effective and easily scalable process, we suggest a new strategy for photocatalytic HI splitting using methylammonium lead iodide (MAPbI3). Considering that MAPbI3 is a water-soluble ionic crystal, we pay attention to the dynamic equilibrium of the precipitation and dissolution of the ionic crystal in saturated solutions. MAPbI3 powder was stably existing in aqueous HI solution by the principle of dynamic equilibrium. The I- and H+ concentrations of the aqueous solution were determined to be the critical parameters for the stabilization of the tetragonal MAPbI3 phase. Stable and efficient H2 production under visible light irradiation was demonstrated. Stoichiometric production of H2 and I3- was verified using GC and UV/Vis spectroscopy measurement, indicating that main photocatalysis by MAPbI3 was HI splitting reaction without side reactions. Indeed, the photocatalytic performance of MAPbI3 can be kept constant even after 160h of continuous illumination of light. Higher photocatalytic H2 generation rate was achieved through Pt cocatalyst deposition and thermal annealing of MAPbI3 in polar solvent atmosphere such as dimethylformamide or dimethyl sulfoxide. The solar HI splitting efficiency of MAPbI3 was 0.81 %, when using Pt as a cocatalyst.

Photocatalytic hydrogen generation from hydriodic acid using methylammonium lead iodide

254th National Meeting (2017)

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