Nowadays, one of the most important challenges in petroleum industry is to remove sulfur compounds from liquid fuels in simple and low-cost ways [1]. Among desulfurization processes, the newly emerged photocatalytic oxidative desulfurization (PODS) has the advantages of milder operating conditions, lower energy consumption, and higher efficiency, holding great prospect to achieve deep desulfurization [2]. After the initial reports on capability of metal-organic frameworks (MOFs) in producing charge separation in the mid-2000s [3,4], research on photoactive MOFs have gained considerable interest. However, the photocatalytic activity of the MOFs-based photocatalysts is still low. Many strategies have been used to overcome this limitation including; 1) doping suitable guest molecules; 2) modification of metallic node (mixed-metal MOF); 3) functionalized organic linker; 4) incorporation of chromophoric struts (antenna effect). These approaches however; are often hard to practice, involve multiple synthetic procedures and sophisticated structures. In this work, we propose defect engineering [5] as a simple strategy in order to induce photoactivity in UiO-66, as a model MOF with zirconium-oxo cluster node, by using modulating agent bearing enediol units, which are able to form inner-sphere charge transfer (CT) complexes, through a one-pot synthetic method. This results in a red shift of the MOF absorption and provide harvesting of solar photon and improves the separation and migration performance of photogenerated electron-hole pairs. In addition, using this method not only altered electronic structure of the MOF, but also changed its porous structure. Compared to pristine UiO-66, the experimental results showed a 35% improvement in the photocatalytic activity of modulated UiO-66 under visible light irradiation.

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