Photo-Activating Biomimetic Polyoxomolybdate for Boosting Oxygen Evolution in Neutral Electrolytes

Inspired by the metal-oxo cluster structural feature and charge separation behaviour of the oxygen evolving center (OEC) in photosystem II (PS-II) under photoirradiation, a new crystalline photochromic polyoxomolybdate, MV2[beta-Mo8O26] (1, MV=methyl viologen cation), is designed as a biomimetic oxygen evolution reaction (OER) catalyst in neutral electrolytes. After photoinduced electron transfer (PIET) with colour change from colourless to grey, it remains in an ultra-stable charge-separated state over a year under ambient conditions. The observed overpotential at 10 mA & sdot; cm-2 and Tafel slope decrease by 49 mV and 62.8 mV & sdot; dec-1 after coloration, respectively. The outstanding OER performance of the coloured state in neutral electrolytes even outperforms the commercial RuO2 benchmark. Experimental and theoretical studies show that oxygen holes within polyanions after irradiation serve as sites for enhancing direct O-O coupling, thus effectively promoting OER. This is the first successful application of electron-transfer photochromism to realize OER activity gain. Electron-transfer photochromism is used to enhance the oxygen evolution reaction (OER) activity, providing an innovative design concept for the development of non-precious metal OER catalysts in artificial photosynthesis devices.+image

Automated summary

In this study, a new crystalline photochromic polyoxomolybdate was designed to act as a biomimetic oxygen evolution reaction (OER) catalyst. It exhibited stable charge separation and excellent OER performance, even outperforming the commercial benchmark, representing a novel design concept for non-precious metal OER catalysts in artificial photosynthesis devices.