Development of Functionalized 'UiO-66 MOF' Embedded Cellulose Nanocomposites for Photoelectrochemical Water Splitting

Economic distress resulting from global dependence on diminishing fossil fuels that adversely impact the environment has led to increased interest in alternative green energy technologies. The photoelectrochemical cell (PEC), provides an attractive green energy solution that incorporates semiconductor materials capable of absorbing visible light to power the splitting of water and create H2 gas, a clean fuel source. PEC systems today, however, are not yet commercially viable due to a lack in efficiency, stability and cost effectiveness. Therefore, the goal of this work is to create a novel, low price semiconducting material to be used as an electrode in a PEC system. This will be accomplished by incorporating the zirconium based Metal Organic Framework (MOF) UiO-66 into a celllulostic network to create a flexible, semiconducting material. The UiO-66 MOF offers a combination of defect sites on the Zr metal cluster and an aromatic linker allowing for light absorption coupled with efficient charge transport. Unfortunately, UiO-66 absorbs in the UV region (2% of sunlight), but its high stability and conjugated organic ligands make it ideal for photosensitization. Simple post synthetic modifications (PSM) can be done to improve light harvesting and electron transport capabilities within the cellulose network. Modifications incorporated in this work include the use of polyaniline crosslinkers as well as metal nanoparticle doping. Conductivity of each material was characterized using a four point probe and measuring current response to applied stepwise voltage. PEC performance was determined by illuminating cell with light and measuring voltage, current and product evolution. Overall, this work provides a foundational design of low cost working electrodes for use in PEC systems, that can lead to future modifications to optimize cell performance.