A first-principles study on the absorption of phosphate on oxygenated graphene for sensing applications Xue Yong and Natalia Martsinovich University of Sheffield, UK Phosphorus is one of the most essential nutrients for plant growth and crop production. However, excess phosphorus in soil can be detrimental to the environment and the plant. Improved phosphorus management would promote the development of profitable and sustainable crop production. 1 However, due to the lack of proper affordable technology, it is currently hard to measure the amount of phosphorus in the soil, therefore a sensor technology needs to be developed. Graphene is a promising sensor material; experiments showed that incorporation of single-layer and multilayer graphene in sensors resulted in significantly improved sensor performance. 2 Therefore, in this work, we investigate pure and oxygenated graphene containing epoxide and hydroxyl groups (labelled “graphene epoxide” and “graphene hydroxides”) as a sensor material for detection of phosphate in the soil through density functional theory (DFT) calculations. This work provides quantitative insight into how different phosphate species (PO 4 3- , OHPO 3 2- , (OH) 2 PO - , (OH) 3 PO) can be adsorbed on the graphene. All the considered phosphate compounds can be physisorbed onto the pristine graphene, graphene epoxide, and graphene hydroxides. Compared with pristine graphene and graphene epoxide, graphene hydroxides show stronger adsorption for all the phosphate species because of hydrogen bonding interactions between the phosphate and the hydroxide groups. The adsorption becomes stronger with the number of formed hydrogen bonding interactions. Significant changes in electrical conductivities before and after adsorbing phosphate species on these pristine or functionalized graphene sheets have been found. In addition, these graphene compounds adsorb of phosphate more strongly than nitrate, therefore showing selectivity towards phosphate. All these results recommended graphene as good candidate for soil phosphorus sensor material. References
1. Franklin D. Roosevelt, Message to Congress. May 20, 1938 [3] 2. He et al. ACS Appl. Mater. Interfaces 2017, 9, 14, 12719–12727
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